1) Cosmic-ray muon radiography was used to precisely characterize a corridor-shaped void (called the ScanPyramids North Face Corridor or NFC) discovered behind the Chevron zone on the north face of Khufu's Pyramid.
2) Nuclear emulsion films and gaseous detectors installed in the pyramid's descending corridor and al-Ma'mun corridor between 2016-2019 revealed the NFC to be approximately 9 meters long, 2 meters wide, and 2 meters high, located slightly above the descending corridor.
3) Comparisons between muon flux observations from the detectors and Geant4 simulations accounting for the pyramid's known structures allowed researchers to accurately determine the dimensions and position of the N
This document summarizes observations of the W49 giant molecular cloud (GMC) using the PMO 14m telescope and the Submillimeter Array (SMA). The PMO observations mapped the entire GMC in various molecular lines at scales up to 113 pc, while the SMA mosaic mapped the central star-forming region W49N at scales down to 0.5 pc. The observations are used to derive the mass structure of the GMC across all scales. The main findings are that the W49 GMC has a total gas mass of 1.1 million solar masses within 60 pc and 2x10^5 solar masses within 6 pc. The mass is distributed in a hierarchical network of filaments converging toward the central
Deep wide field_and_panchromatic_view_of_47_tuc_and_smc_with_hubbleSérgio Sacani
This document describes a deep imaging survey of the globular cluster 47 Tucanae and the Small Magellanic Cloud conducted with the Hubble Space Telescope. Over 700 images were taken with the ACS and WFC3 instruments in six filters spanning wavelengths from 0.4 to 1.7 microns. The images were combined into ultra-deep stacks to study the faintest stars in 47 Tuc down to 30th magnitude in visible light and 27th magnitude in infrared. The data also provide the deepest view of the lower main sequence of the SMC. Careful photometric and astrometric measurements on the stacks reveal unprecedented color-magnitude diagrams of the stellar populations.
Laser melting manufacturing of large elements of lunar regolith simulant for ...Sérgio Sacani
The next steps for the expansion of the human presence in the solar system will be taken on the Moon.
However, due to the low lunar gravity, the suspended dust generated when lunar rovers move across
the lunar soil is a signifcant risk for lunar missions as it can afect the systems of the exploration
vehicles. One solution to mitigate this problem is the construction of roads and landing pads on the
Moon. In addition, to increase the sustainability of future lunar missions, in-situ resource utilization
(ISRU) techniques must be developed. In this paper, the use of concentrated light for paving on the
Moon by melting the lunar regolith is investigated. As a substitute of the concentrated sunlight, a
high-power CO2 laser is used in the experiments. With this set-up, a maximum laser spot diameter of
100 mm can be achieved, which translates in high thicknesses of the consolidated layers. Furthermore,
the lunar regolith simulant EAC-1A is used as a substitute of the actual lunar soil. At the end of the
study, large samples (approximately 250 × 250 mm) with interlocking capabilities were fabricated by
melting the lunar simulant with the laser directly on the powder bed. Large areas of lunar soil can be
covered with these samples and serve as roads and landing pads, decreasing the propagation of lunar
dust. These manufactured samples were analysed regarding their mineralogical composition, internal
structure and mechanical properties.
Fleeting Small-scale Surface Magnetic Fields Build the Quiet-Sun CoronaSérgio Sacani
Arch-like loop structures filled with million Kelvin hot plasma form the building blocks of the quiet-Sun corona.
Both high-resolution observations and magnetoconvection simulations show the ubiquitous presence of magnetic
fields on the solar surface on small spatial scales of ∼100 km. However, the question of how exactly these quietSun coronal loops originate from the photosphere and how the magnetic energy from the surface is channeled to
heat the overlying atmosphere is a long-standing puzzle. Here we report high-resolution photospheric magnetic
field and coronal data acquired during the second science perihelion of Solar Orbiter that reveal a highly dynamic
magnetic landscape underlying the observed quiet-Sun corona. We found that coronal loops often connect to
surface regions that harbor fleeting weaker, mixed-polarity magnetic field patches structured on small spatial
scales, and that coronal disturbances could emerge from these areas. We suggest that weaker magnetic fields with
fluxes as low as 1015 Mx and/or those that evolve on timescales less than 5 minutes are crucial to understanding
the coronal structuring and dynamics.
Kinetic Energy Transfer of Near-Earth Objects for Interplanetary Manned Missi...Winston Sanks
This report outlines the rationale, procedures, technical feasibility, risk assessment, and cost-benefit analysis of utilizing a Near-Earth Object, 101955 Bennu (provisional designation 1999 RQ36 - the target of the OSIRIS-REx mission), as a source of energy to minimize the propulsion requirements of an interplanetary spacecraft. The planet Mars is the target body in this study and the outbound Trans-Mars injection in the years between 2175 and 2199 will be analyzed (within this timeframe Bennu’s orbit is predicted to approach Earth within two Earth radii on at least 80 occasions). The Mars orbit insertion burn, Trans-Earth injection burn, and Earth orbit insertion burn are assumed to be achieved with propulsive maneuvers outlined in standard manned interplanetary mission architectures. To accomplish this mission, two methods of transferring kinetic energy are examined: direct capture and release of the asteroid by a spacecraft using a Kevlar net and an inertial reel, and indirect capture by establishing a station on the asteroid to manufacture compressed material from the carbonaceous regolith in order to fire a mass stream to be captured by the spacecraft. This mission architecture analysis takes into account the associated safety risks of perturbations within Bennu’s orbit (which could result in inaccurate rendezvous location predictions), the implications of altering the orbit of 101955 Bennu after transferring a portion of its energy (since there is a possibility of collision with Earth in the late 22nd century if the asteroid is slowed too significantly), g-limit restrictions of the spacecraft and its occupants during an acceleration by the asteroid, and the possibility of a collision between Bennu and the spacecraft. In addition, the cost-benefit considerations of this mission architecture are weighed. This examination concludes that a direct capture Net and Reel system aboard the spacecraft is not a viable capture method due to an insufficient maximum ΔV available through a best-case perfectly elastic collision (capture) with the asteroid, as well as a prohibitive weight penalty aboard the spacecraft due to the Net and Reel system. However, this report finds that the method of establishing a station on Bennu with the capability to separate mass from the asteroid and fire it at a spacecraft is a plausible (if costly) means of transferring a significant ΔV. A KETNEO-FIMM Asteroid Station mission architecture could also be used in subsequent interplanetary missions providing cost-sharing over many decades for future interplanetary missions.
The article discusses observations from multiple space-based observatories that tracked a sun-diving comet, C/2011 N3 (SOHO), as it passed through the Sun's corona and disintegrated. The observatories captured details of the comet's flight path, emissions, and disintegration over time. Studying how comets interact with and break apart in the corona can provide insights into comet composition and the early solar system.
ScanPyramids – Results from the first measurements campaign in the Bent Pyr...Leonardo Paolo Lovari
The #ScanPyramids team presented results from muon tomography scans of the Bent Pyramid to Egyptian antiquities officials. The scans revealed the internal structure of the pyramid, including the location of the second chamber approximately 18 meters above the first. While more data is needed to identify known corridors precisely, simulations validated there is no additional large chamber in the area scanned. This validates muon scanning as a technique for exploring the internal structures of Egyptian pyramids without invasive methods.
This document summarizes observations of the W49 giant molecular cloud (GMC) using the PMO 14m telescope and the Submillimeter Array (SMA). The PMO observations mapped the entire GMC in various molecular lines at scales up to 113 pc, while the SMA mosaic mapped the central star-forming region W49N at scales down to 0.5 pc. The observations are used to derive the mass structure of the GMC across all scales. The main findings are that the W49 GMC has a total gas mass of 1.1 million solar masses within 60 pc and 2x10^5 solar masses within 6 pc. The mass is distributed in a hierarchical network of filaments converging toward the central
Deep wide field_and_panchromatic_view_of_47_tuc_and_smc_with_hubbleSérgio Sacani
This document describes a deep imaging survey of the globular cluster 47 Tucanae and the Small Magellanic Cloud conducted with the Hubble Space Telescope. Over 700 images were taken with the ACS and WFC3 instruments in six filters spanning wavelengths from 0.4 to 1.7 microns. The images were combined into ultra-deep stacks to study the faintest stars in 47 Tuc down to 30th magnitude in visible light and 27th magnitude in infrared. The data also provide the deepest view of the lower main sequence of the SMC. Careful photometric and astrometric measurements on the stacks reveal unprecedented color-magnitude diagrams of the stellar populations.
Laser melting manufacturing of large elements of lunar regolith simulant for ...Sérgio Sacani
The next steps for the expansion of the human presence in the solar system will be taken on the Moon.
However, due to the low lunar gravity, the suspended dust generated when lunar rovers move across
the lunar soil is a signifcant risk for lunar missions as it can afect the systems of the exploration
vehicles. One solution to mitigate this problem is the construction of roads and landing pads on the
Moon. In addition, to increase the sustainability of future lunar missions, in-situ resource utilization
(ISRU) techniques must be developed. In this paper, the use of concentrated light for paving on the
Moon by melting the lunar regolith is investigated. As a substitute of the concentrated sunlight, a
high-power CO2 laser is used in the experiments. With this set-up, a maximum laser spot diameter of
100 mm can be achieved, which translates in high thicknesses of the consolidated layers. Furthermore,
the lunar regolith simulant EAC-1A is used as a substitute of the actual lunar soil. At the end of the
study, large samples (approximately 250 × 250 mm) with interlocking capabilities were fabricated by
melting the lunar simulant with the laser directly on the powder bed. Large areas of lunar soil can be
covered with these samples and serve as roads and landing pads, decreasing the propagation of lunar
dust. These manufactured samples were analysed regarding their mineralogical composition, internal
structure and mechanical properties.
Fleeting Small-scale Surface Magnetic Fields Build the Quiet-Sun CoronaSérgio Sacani
Arch-like loop structures filled with million Kelvin hot plasma form the building blocks of the quiet-Sun corona.
Both high-resolution observations and magnetoconvection simulations show the ubiquitous presence of magnetic
fields on the solar surface on small spatial scales of ∼100 km. However, the question of how exactly these quietSun coronal loops originate from the photosphere and how the magnetic energy from the surface is channeled to
heat the overlying atmosphere is a long-standing puzzle. Here we report high-resolution photospheric magnetic
field and coronal data acquired during the second science perihelion of Solar Orbiter that reveal a highly dynamic
magnetic landscape underlying the observed quiet-Sun corona. We found that coronal loops often connect to
surface regions that harbor fleeting weaker, mixed-polarity magnetic field patches structured on small spatial
scales, and that coronal disturbances could emerge from these areas. We suggest that weaker magnetic fields with
fluxes as low as 1015 Mx and/or those that evolve on timescales less than 5 minutes are crucial to understanding
the coronal structuring and dynamics.
Kinetic Energy Transfer of Near-Earth Objects for Interplanetary Manned Missi...Winston Sanks
This report outlines the rationale, procedures, technical feasibility, risk assessment, and cost-benefit analysis of utilizing a Near-Earth Object, 101955 Bennu (provisional designation 1999 RQ36 - the target of the OSIRIS-REx mission), as a source of energy to minimize the propulsion requirements of an interplanetary spacecraft. The planet Mars is the target body in this study and the outbound Trans-Mars injection in the years between 2175 and 2199 will be analyzed (within this timeframe Bennu’s orbit is predicted to approach Earth within two Earth radii on at least 80 occasions). The Mars orbit insertion burn, Trans-Earth injection burn, and Earth orbit insertion burn are assumed to be achieved with propulsive maneuvers outlined in standard manned interplanetary mission architectures. To accomplish this mission, two methods of transferring kinetic energy are examined: direct capture and release of the asteroid by a spacecraft using a Kevlar net and an inertial reel, and indirect capture by establishing a station on the asteroid to manufacture compressed material from the carbonaceous regolith in order to fire a mass stream to be captured by the spacecraft. This mission architecture analysis takes into account the associated safety risks of perturbations within Bennu’s orbit (which could result in inaccurate rendezvous location predictions), the implications of altering the orbit of 101955 Bennu after transferring a portion of its energy (since there is a possibility of collision with Earth in the late 22nd century if the asteroid is slowed too significantly), g-limit restrictions of the spacecraft and its occupants during an acceleration by the asteroid, and the possibility of a collision between Bennu and the spacecraft. In addition, the cost-benefit considerations of this mission architecture are weighed. This examination concludes that a direct capture Net and Reel system aboard the spacecraft is not a viable capture method due to an insufficient maximum ΔV available through a best-case perfectly elastic collision (capture) with the asteroid, as well as a prohibitive weight penalty aboard the spacecraft due to the Net and Reel system. However, this report finds that the method of establishing a station on Bennu with the capability to separate mass from the asteroid and fire it at a spacecraft is a plausible (if costly) means of transferring a significant ΔV. A KETNEO-FIMM Asteroid Station mission architecture could also be used in subsequent interplanetary missions providing cost-sharing over many decades for future interplanetary missions.
The article discusses observations from multiple space-based observatories that tracked a sun-diving comet, C/2011 N3 (SOHO), as it passed through the Sun's corona and disintegrated. The observatories captured details of the comet's flight path, emissions, and disintegration over time. Studying how comets interact with and break apart in the corona can provide insights into comet composition and the early solar system.
ScanPyramids – Results from the first measurements campaign in the Bent Pyr...Leonardo Paolo Lovari
The #ScanPyramids team presented results from muon tomography scans of the Bent Pyramid to Egyptian antiquities officials. The scans revealed the internal structure of the pyramid, including the location of the second chamber approximately 18 meters above the first. While more data is needed to identify known corridors precisely, simulations validated there is no additional large chamber in the area scanned. This validates muon scanning as a technique for exploring the internal structures of Egyptian pyramids without invasive methods.
Spirals and clumps in V960 Mon: signs of planet formation via gravitational i...Sérgio Sacani
The formation of giant planets has traditionally been divided into two pathways: core accretion and gravitational instability. However, in recent years, gravitational instability has become less favored, primarily due
to the scarcity of observations of fragmented protoplanetary disks around young stars and low occurrence rate
of massive planets on very wide orbits. In this study, we present a SPHERE/IRDIS polarized light observation
of the young outbursting object V960 Mon. The image reveals a vast structure of intricately shaped scattered
light with several spiral arms. This finding motivated a re-analysis of archival ALMA 1.3 mm data acquired
just two years after the onset of the outburst of V960 Mon. In these data, we discover several clumps of continuum emission aligned along a spiral arm that coincides with the scattered light structure. We interpret the
localized emission as fragments formed from a spiral arm under gravitational collapse. Estimating the mass of
solids within these clumps to be of several Earth masses, we suggest this observation to be the first evidence of
gravitational instability occurring on planetary scales. This study discusses the significance of this finding for
planet formation and its potential connection with the outbursting state of V960 Mon.
The document summarizes findings from the Microwave Instrument on the Rosetta Orbiter (MIRO) regarding the subsurface properties and early activity of comet 67P/Churyumov-Gerasimenko. Key points:
- MIRO detected water vapor emissions from the comet beginning in early June 2014 and measured the total water production rate, which varied from 0.3 kg/s to 1.2 kg/s between June and August.
- Water outgassing displayed periodic variations correlated with the comet's 12.4-hour rotation period and seemed to originate primarily from the comet's "neck" region.
- Subsurface temperatures measured by MIRO showed seasonal and diurnal variations, indicating radiation
Citizen science projects have the potential to transform earthquake detection by greatly increasing the number of seismic sensor locations. Individuals can host sensors in their homes and buildings to record ground motion data during quakes. However, data quality standards must be maintained and networks need to remain operational long-term for the data to be scientifically useful. If these challenges can be addressed, dense citizen sensor networks may provide new insights into earthquake processes.
This document summarizes research verifying simulations of a novel muon radiography detector system through experimentation. It estimates the detector's spatial resolution as 9.32mm, better than the 1cm reported previously. It also explores the detector's imaging potential through both simulation and initial promising experimental results. The document provides background on muon production, tomography using scattering angles, and radiography using transmission measurements. It describes common detector types and current applications like border security using large-scale muon tomography to detect nuclear materials more effectively than gamma-ray systems.
First Direct Imaging of a Kelvin–Helmholtz Instability by PSP/WISPRSérgio Sacani
We present a comprehensive analysis aimed at proving the hypothesis that a train of small-scale features observed by the Wide-field Imager (WISPR) onboard the Parker Solar Probe (PSP) are the signature of a Kelvin–Helmholtz instability (KHI). These features were seen near the flank of a Coronal Mass Ejection (CME) wake between 7.5 Re and 9.5Re, lasting for about 30 minutes. The CME was a slow event, associated with a streamer blowout. We analyzed the size of the eddies and found growth during their evolution while maintaining separation distances and alignment typical of Kelvin–Helmholtz vortexes. We then assessed the magnetic field conditions that would make the observation of such an instability plausible. Two methods were used to cross-check our findings. The measured thickness of the boundary layer supports KHI candidacy, and the estimated linear growth rate suggests nonlinear saturation within the expected timescale. We conclude that a KHI is a plausible explanation for the observed features, and therefore that such instabilities might exist in the low and middle solar corona (within ∼15 Re) and can be detected in white light observations. Their observation, however, might be rare due to stringent conditions like the observer’s proximity, suitable viewing circumstances, magnetic field topology, and flow properties. This study highlights the unique capability of PSP/WISPR in observing such phenomena, especially as PSP perihelia reach closer distances to the Sun.
My Hydrospatial 21 presentation titled "Back to the Future: The Climate for Change and the Hydrographer of the Future" contained a number of slides noting supplement.
This presentation is the Rosetta link. It suggests that visionary capabilities are possible and uses components of the Rosetta mission with past capabilities.
Lunar Base Architecture and Operations ProposalDavid Torre
The document proposes the architecture and operations of the Jamestown Moon Base located near the South Pole of the Moon. Key aspects of the proposal include:
1. Establishing a permanently crewed base with modules to support 4 crew primarily for scientific research and exploration of the Moon.
2. Locating the base in Amundsen crater for its proximity to resources like water ice, flat terrain, and protection from radiation.
3. Designing the base with interconnected pressurized modules for living/working spaces and unpressurized areas for vehicle/equipment storage and processing resources.
First wide field-of-view X-ray observations by a lobster eye focusing telesco...Sérgio Sacani
The document describes the first results from LEIA, a lobster eye X-ray telescope launched as a pathfinder for the Einstein Probe mission. Key results include:
- LEIA has a wide field of view of 18.6°x18.6° and achieved its expected spatial resolution of 4-7 arcmin and effective area of 2-3 cm^2 across most of the field of view.
- LEIA took snapshot images of the Galactic center region, Sco X-1, and the Cygnus Loop nebula, representing the first truly wide-field X-ray images captured by a focusing X-ray telescope.
- Initial analyses found excellent agreement between the observed images and ground cal
O telescópio de rastreio VISTA do ESO encontrou uma horda de galáxias massivas anteriormente ocultas por poeira, que existiram quando o Universo era ainda bebê. Ao descobrir e estudar uma grande quantidade deste tipo de galáxias, os astrônomos descobriram, exatamente e pela primeira vez, quando é que tais monstros apareceram pela primeira vez no Universo.
O simples fato de contar o número de galáxias que existem em determinada área do céu permite aos astrônomos testar teorias de formação e evolução galática. No entanto, uma tarefa aparentemente tão fácil torna-se mais difícil quando tentamos contar galáxias cada vez mais distantes e tênues e é mais complicada ainda devido ao fato das galáxias mais brilhantes e fáceis de observar — as mais massivas no Universo — se tornarem mais raras à medida que os astrônomos observam o passado do Universo, enquanto que as galáxias menos brilhantes, mas muito mais numerosas, são ainda mais difíceis de detectar.
Uma equipe de astrônomos liderada por Karina Caputi do Instituto Astronômico Kapteyn da Universidade de Groningen, descobriu muitas galáxias distantes que não tinham sido detectadas anteriormente. A equipe utilizou imagens do rastreioUltraVISTA, um dos seis projetos que usam o VISTA para mapear o céu no infravermelho próximo, e fez um censo das galáxias tênues quando a idade do Universo estava compreendida entre 0,75 e 2,1 bilhões de anos.
A super earth transiting a naked-eye starSérgio Sacani
This document summarizes the detection of transits of an exoplanet orbiting the star 55 Cnc, using photometry from the MOST space telescope. The transits match the period, phase, duration, and depth predicted for the innermost planet of 55 Cnc, designated 55 Cnc e. Analysis of the transit data indicates the planet has a mass of 8.57 Earth masses, a radius of 1.63 Earth radii, and a dense composition of rock and iron. This makes 55 Cnc e similar to other dense super-Earth exoplanets in short orbits, unlike lower-density super-Earths further from their stars. The brightness of 55 Cnc will enable further study of this transiting exoplanet system.
The document analyzes morphological and compositional data of the central peak of Tycho crater on the Moon. Analysis of high-resolution Chandrayaan-1 and LRO data reveals evidence of volcanic features on the central peak, including volcanic vents, lava ponds showing cooling cracks, lava flows, and domes. Compositionally, M3 data show the central peak is heterogeneous and dominated by high-Ca pyroxene-rich rocks, with an anorthositic base. These morphological and mineralogical features suggest the central peak underwent multiple modifications after impact, exposing deep lunar crustal materials through volcanism triggered by the impact event.
This document summarizes research using deep seismic sounding by microtremor (SSMT) broadband signals to study the Vrancea seismic zone in Romania. The SSMT methodology analyzes spatial variations in microseismic noise spectra to image subsurface structures. Results show a low-velocity seismic boundary in the focal zone from 170-280km depth. High-velocity structures west and east of the zone may represent the Intra-Carpathian subplate and Moessian platform. Hypocenters localized in intermediate velocities between the low-velocity zone below and high-velocity structures at sides. Comparisons support findings. Repeated experiments yielded consistent results, validating the SSMT method.
This document presents the results of a study of 32 Bok globules, which are small, isolated molecular clouds that often contain young stellar objects. Millimeter and submillimeter continuum images were used to detect dust emission from star-forming cores within the globules. These data, along with infrared images and spectral energy distributions, were analyzed to determine the physical properties and evolutionary stages of the embedded sources. Submillimeter dust emission was detected in 26 globules, and the analysis identified 9 starless cores, 9 Class 0 protostars, and 12 Class I young stellar objects. The study found evidence that at least two-thirds of the globules studied were forming multiple stars within distances of 1,000-50,000 AU of each
The document provides an overview of a project analyzing data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument aboard the Mars Reconnaissance Orbiter. It discusses CRISM's goals of identifying mineral evidence of past water on Mars. It outlines the project's methodology which involves collaborating with CRISM scientists to assist with analyzing over 10 terabytes of CRISM data using a graphical user interface. It also discusses educational outreach efforts to engage students in remote sensing and share the project's findings.
An infrared transient from a star engulfing a planetSérgio Sacani
Planets with short orbital periods (roughly under 10 days) are common around stars like the Sun1,2. Stars expand as they evolve and thus we expect their close planetary companions to be engulfed, possibly powering luminous mass ejections from the host star3–5. However, this phase has never been directly observed. Here we report observations of ZTF SLRN-2020, a short-lived optical outburst in the Galactic disk accompanied by bright and long-lived infrared emission. The resulting light curve and spectra share striking similarities with those of red novae6,7—a class of eruptions now confirmed8 to arise from mergers of binary stars. Its exceptionally low optical luminosity (approximately 1035 erg s−1) and radiated energy (approximately 6.5 × 1041 erg) point to the engulfment of a planet of fewer than roughly ten Jupiter masses by its Sun-like host star. We estimate the Galactic rate of such subluminous red novae to be roughly between 0.1 and several per year. Future Galactic plane surveys should routinely identify these, showing the demographics of planetary engulfment and the ultimate fate of planets in the inner Solar System.
The document proposes a mission to survey lunar lava tubes using an orbiter/lander combination delivered by a SHERPA 2200 tug. The mission objectives are to map the depth, volume and extent of subsurface empty lava tubes using ground penetrating radar on the orbiter and lander. Tensegrity landing technology allows precise landing of the payload-carrying lander. Characterizing lava tubes could identify potential sites for future human habitation under lunar surface. The proposal outlines the mission design, spacecraft and payloads, and organizational roles to conduct the low-cost survey.
An extremely high_altitude_plume_seen_at_mars_morning_terminatorSérgio Sacani
Artigo da revista Nature que descreve as plumas de alta altitude identificadas pairando sobre a superfície do planeta Marte e propõem duas hipóteses para o fenômeno.
This proposal requests 14 nights in January through April to use the 1-meter Ritchey-Chretien telescope at Embry-Riddle Aeronautical University to perform photometry on the Seyfert 2 galaxy Messier 106. The goal is to study H-II regions within M106, which are sites of ongoing star formation, and determine the star formation rates within selected regions. Photometry using H-alpha and infrared filters will measure the surface brightness, temperature, and ionization processes of the H-II regions to estimate the number of newly formed stars. Understanding star formation rates in different regions will provide insight into factors influencing the creation of new stars within galaxies.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
More Related Content
Similar to Precise characterization of a corridor-shaped structure in Khufu’s Pyramid by observation of cosmic-ray muons
Spirals and clumps in V960 Mon: signs of planet formation via gravitational i...Sérgio Sacani
The formation of giant planets has traditionally been divided into two pathways: core accretion and gravitational instability. However, in recent years, gravitational instability has become less favored, primarily due
to the scarcity of observations of fragmented protoplanetary disks around young stars and low occurrence rate
of massive planets on very wide orbits. In this study, we present a SPHERE/IRDIS polarized light observation
of the young outbursting object V960 Mon. The image reveals a vast structure of intricately shaped scattered
light with several spiral arms. This finding motivated a re-analysis of archival ALMA 1.3 mm data acquired
just two years after the onset of the outburst of V960 Mon. In these data, we discover several clumps of continuum emission aligned along a spiral arm that coincides with the scattered light structure. We interpret the
localized emission as fragments formed from a spiral arm under gravitational collapse. Estimating the mass of
solids within these clumps to be of several Earth masses, we suggest this observation to be the first evidence of
gravitational instability occurring on planetary scales. This study discusses the significance of this finding for
planet formation and its potential connection with the outbursting state of V960 Mon.
The document summarizes findings from the Microwave Instrument on the Rosetta Orbiter (MIRO) regarding the subsurface properties and early activity of comet 67P/Churyumov-Gerasimenko. Key points:
- MIRO detected water vapor emissions from the comet beginning in early June 2014 and measured the total water production rate, which varied from 0.3 kg/s to 1.2 kg/s between June and August.
- Water outgassing displayed periodic variations correlated with the comet's 12.4-hour rotation period and seemed to originate primarily from the comet's "neck" region.
- Subsurface temperatures measured by MIRO showed seasonal and diurnal variations, indicating radiation
Citizen science projects have the potential to transform earthquake detection by greatly increasing the number of seismic sensor locations. Individuals can host sensors in their homes and buildings to record ground motion data during quakes. However, data quality standards must be maintained and networks need to remain operational long-term for the data to be scientifically useful. If these challenges can be addressed, dense citizen sensor networks may provide new insights into earthquake processes.
This document summarizes research verifying simulations of a novel muon radiography detector system through experimentation. It estimates the detector's spatial resolution as 9.32mm, better than the 1cm reported previously. It also explores the detector's imaging potential through both simulation and initial promising experimental results. The document provides background on muon production, tomography using scattering angles, and radiography using transmission measurements. It describes common detector types and current applications like border security using large-scale muon tomography to detect nuclear materials more effectively than gamma-ray systems.
First Direct Imaging of a Kelvin–Helmholtz Instability by PSP/WISPRSérgio Sacani
We present a comprehensive analysis aimed at proving the hypothesis that a train of small-scale features observed by the Wide-field Imager (WISPR) onboard the Parker Solar Probe (PSP) are the signature of a Kelvin–Helmholtz instability (KHI). These features were seen near the flank of a Coronal Mass Ejection (CME) wake between 7.5 Re and 9.5Re, lasting for about 30 minutes. The CME was a slow event, associated with a streamer blowout. We analyzed the size of the eddies and found growth during their evolution while maintaining separation distances and alignment typical of Kelvin–Helmholtz vortexes. We then assessed the magnetic field conditions that would make the observation of such an instability plausible. Two methods were used to cross-check our findings. The measured thickness of the boundary layer supports KHI candidacy, and the estimated linear growth rate suggests nonlinear saturation within the expected timescale. We conclude that a KHI is a plausible explanation for the observed features, and therefore that such instabilities might exist in the low and middle solar corona (within ∼15 Re) and can be detected in white light observations. Their observation, however, might be rare due to stringent conditions like the observer’s proximity, suitable viewing circumstances, magnetic field topology, and flow properties. This study highlights the unique capability of PSP/WISPR in observing such phenomena, especially as PSP perihelia reach closer distances to the Sun.
My Hydrospatial 21 presentation titled "Back to the Future: The Climate for Change and the Hydrographer of the Future" contained a number of slides noting supplement.
This presentation is the Rosetta link. It suggests that visionary capabilities are possible and uses components of the Rosetta mission with past capabilities.
Lunar Base Architecture and Operations ProposalDavid Torre
The document proposes the architecture and operations of the Jamestown Moon Base located near the South Pole of the Moon. Key aspects of the proposal include:
1. Establishing a permanently crewed base with modules to support 4 crew primarily for scientific research and exploration of the Moon.
2. Locating the base in Amundsen crater for its proximity to resources like water ice, flat terrain, and protection from radiation.
3. Designing the base with interconnected pressurized modules for living/working spaces and unpressurized areas for vehicle/equipment storage and processing resources.
First wide field-of-view X-ray observations by a lobster eye focusing telesco...Sérgio Sacani
The document describes the first results from LEIA, a lobster eye X-ray telescope launched as a pathfinder for the Einstein Probe mission. Key results include:
- LEIA has a wide field of view of 18.6°x18.6° and achieved its expected spatial resolution of 4-7 arcmin and effective area of 2-3 cm^2 across most of the field of view.
- LEIA took snapshot images of the Galactic center region, Sco X-1, and the Cygnus Loop nebula, representing the first truly wide-field X-ray images captured by a focusing X-ray telescope.
- Initial analyses found excellent agreement between the observed images and ground cal
O telescópio de rastreio VISTA do ESO encontrou uma horda de galáxias massivas anteriormente ocultas por poeira, que existiram quando o Universo era ainda bebê. Ao descobrir e estudar uma grande quantidade deste tipo de galáxias, os astrônomos descobriram, exatamente e pela primeira vez, quando é que tais monstros apareceram pela primeira vez no Universo.
O simples fato de contar o número de galáxias que existem em determinada área do céu permite aos astrônomos testar teorias de formação e evolução galática. No entanto, uma tarefa aparentemente tão fácil torna-se mais difícil quando tentamos contar galáxias cada vez mais distantes e tênues e é mais complicada ainda devido ao fato das galáxias mais brilhantes e fáceis de observar — as mais massivas no Universo — se tornarem mais raras à medida que os astrônomos observam o passado do Universo, enquanto que as galáxias menos brilhantes, mas muito mais numerosas, são ainda mais difíceis de detectar.
Uma equipe de astrônomos liderada por Karina Caputi do Instituto Astronômico Kapteyn da Universidade de Groningen, descobriu muitas galáxias distantes que não tinham sido detectadas anteriormente. A equipe utilizou imagens do rastreioUltraVISTA, um dos seis projetos que usam o VISTA para mapear o céu no infravermelho próximo, e fez um censo das galáxias tênues quando a idade do Universo estava compreendida entre 0,75 e 2,1 bilhões de anos.
A super earth transiting a naked-eye starSérgio Sacani
This document summarizes the detection of transits of an exoplanet orbiting the star 55 Cnc, using photometry from the MOST space telescope. The transits match the period, phase, duration, and depth predicted for the innermost planet of 55 Cnc, designated 55 Cnc e. Analysis of the transit data indicates the planet has a mass of 8.57 Earth masses, a radius of 1.63 Earth radii, and a dense composition of rock and iron. This makes 55 Cnc e similar to other dense super-Earth exoplanets in short orbits, unlike lower-density super-Earths further from their stars. The brightness of 55 Cnc will enable further study of this transiting exoplanet system.
The document analyzes morphological and compositional data of the central peak of Tycho crater on the Moon. Analysis of high-resolution Chandrayaan-1 and LRO data reveals evidence of volcanic features on the central peak, including volcanic vents, lava ponds showing cooling cracks, lava flows, and domes. Compositionally, M3 data show the central peak is heterogeneous and dominated by high-Ca pyroxene-rich rocks, with an anorthositic base. These morphological and mineralogical features suggest the central peak underwent multiple modifications after impact, exposing deep lunar crustal materials through volcanism triggered by the impact event.
This document summarizes research using deep seismic sounding by microtremor (SSMT) broadband signals to study the Vrancea seismic zone in Romania. The SSMT methodology analyzes spatial variations in microseismic noise spectra to image subsurface structures. Results show a low-velocity seismic boundary in the focal zone from 170-280km depth. High-velocity structures west and east of the zone may represent the Intra-Carpathian subplate and Moessian platform. Hypocenters localized in intermediate velocities between the low-velocity zone below and high-velocity structures at sides. Comparisons support findings. Repeated experiments yielded consistent results, validating the SSMT method.
This document presents the results of a study of 32 Bok globules, which are small, isolated molecular clouds that often contain young stellar objects. Millimeter and submillimeter continuum images were used to detect dust emission from star-forming cores within the globules. These data, along with infrared images and spectral energy distributions, were analyzed to determine the physical properties and evolutionary stages of the embedded sources. Submillimeter dust emission was detected in 26 globules, and the analysis identified 9 starless cores, 9 Class 0 protostars, and 12 Class I young stellar objects. The study found evidence that at least two-thirds of the globules studied were forming multiple stars within distances of 1,000-50,000 AU of each
The document provides an overview of a project analyzing data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument aboard the Mars Reconnaissance Orbiter. It discusses CRISM's goals of identifying mineral evidence of past water on Mars. It outlines the project's methodology which involves collaborating with CRISM scientists to assist with analyzing over 10 terabytes of CRISM data using a graphical user interface. It also discusses educational outreach efforts to engage students in remote sensing and share the project's findings.
An infrared transient from a star engulfing a planetSérgio Sacani
Planets with short orbital periods (roughly under 10 days) are common around stars like the Sun1,2. Stars expand as they evolve and thus we expect their close planetary companions to be engulfed, possibly powering luminous mass ejections from the host star3–5. However, this phase has never been directly observed. Here we report observations of ZTF SLRN-2020, a short-lived optical outburst in the Galactic disk accompanied by bright and long-lived infrared emission. The resulting light curve and spectra share striking similarities with those of red novae6,7—a class of eruptions now confirmed8 to arise from mergers of binary stars. Its exceptionally low optical luminosity (approximately 1035 erg s−1) and radiated energy (approximately 6.5 × 1041 erg) point to the engulfment of a planet of fewer than roughly ten Jupiter masses by its Sun-like host star. We estimate the Galactic rate of such subluminous red novae to be roughly between 0.1 and several per year. Future Galactic plane surveys should routinely identify these, showing the demographics of planetary engulfment and the ultimate fate of planets in the inner Solar System.
The document proposes a mission to survey lunar lava tubes using an orbiter/lander combination delivered by a SHERPA 2200 tug. The mission objectives are to map the depth, volume and extent of subsurface empty lava tubes using ground penetrating radar on the orbiter and lander. Tensegrity landing technology allows precise landing of the payload-carrying lander. Characterizing lava tubes could identify potential sites for future human habitation under lunar surface. The proposal outlines the mission design, spacecraft and payloads, and organizational roles to conduct the low-cost survey.
An extremely high_altitude_plume_seen_at_mars_morning_terminatorSérgio Sacani
Artigo da revista Nature que descreve as plumas de alta altitude identificadas pairando sobre a superfície do planeta Marte e propõem duas hipóteses para o fenômeno.
This proposal requests 14 nights in January through April to use the 1-meter Ritchey-Chretien telescope at Embry-Riddle Aeronautical University to perform photometry on the Seyfert 2 galaxy Messier 106. The goal is to study H-II regions within M106, which are sites of ongoing star formation, and determine the star formation rates within selected regions. Photometry using H-alpha and infrared filters will measure the surface brightness, temperature, and ionization processes of the H-II regions to estimate the number of newly formed stars. Understanding star formation rates in different regions will provide insight into factors influencing the creation of new stars within galaxies.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Similar to Precise characterization of a corridor-shaped structure in Khufu’s Pyramid by observation of cosmic-ray muons (20)
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
ESPP presentation to EU Waste Water Network, 4th June 2024 “EU policies driving nutrient removal and recycling
and the revised UWWTD (Urban Waste Water Treatment Directive)”
Precise characterization of a corridor-shaped structure in Khufu’s Pyramid by observation of cosmic-ray muons
1. Article https://doi.org/10.1038/s41467-023-36351-0
Precise characterization of a corridor-shaped
structure in Khufu’s Pyramid by observation
of cosmic-ray muons
Sébastien Procureur 1,12
, Kunihiro Morishima 2,3,12
, Mitsuaki Kuno2
,
Yuta Manabe2
, Nobuko Kitagawa2
, Akira Nishio2
, Hector Gomez 1
, David Attié 1
,
Ami Sakakibara2
, Kotaro Hikata2
, Masaki Moto2
, Irakli Mandjavidze 1
,
Patrick Magnier1
, Marion Lehuraux 1
, Théophile Benoit1
, Denis Calvet 1
,
Xavier Coppolani1
, Mariam Kebbiri1
, Philippe Mas1
, Hany Helal4,5
,
Mehdi Tayoubi5,6
, Benoit Marini 5,7
, Nicolas Serikoff5
, Hamada Anwar4
,
Vincent Steiger5
, Fumihiko Takasaki8
, Hirofumi Fujii8
, Kotaro Satoh8
,
Hideyo Kodama8
, Kohei Hayashi8
, Pierre Gable9
, Emmanuel Guerriero9
,
Jean-Baptiste Mouret 10
, Tamer Elnady 11
, Yasser Elshayeb 4
&
Mohamed Elkarmoty 4
Khufu’s Pyramid is one of the largest archaeological monument all over the
world, which still holds many mysteries. In 2016 and 2017, the ScanPyramids
team reported on several discoveries of previously unknown voids by cosmic-
ray muon radiography that is a non-destructive technique ideal for the
investigation of large-scale structures. Among these discoveries, a corridor-
shaped structure has been observed behind the so-called Chevron zone on the
North face, with a length of at least 5 meters. A dedicated study of this struc-
ture was thus necessary to better understand its function in relation with the
enigmatic architectural role of this Chevron. Here we report on new mea-
surements of excellent sensitivity obtained with nuclear emulsion films from
Nagoya University and gaseous detectors from CEA, revealing a structure of
about 9 m length with a transverse section of about 2.0 m by 2.0 m.
The Great Pyramid is one of the largest stone structures in the world,
built 4500 years ago by the king Khufu, king Snefru’s son, on the Giza
plateau of necropolis in Egypt. It was expected to be over 146 m high,
before its smooth outer coating was stripped off by carriers in the
Middle Ages as well as the capstone on the top. Today, the pyramid is
139 m high and 230 m wide, and is thought to be made of several
million pieces of limestone, each about 1–2 m high. There are large
internal structures in its massive stone body, connected by narrow
corridors in the north-south direction at a distance of about 7 m east
from the center of the pyramid (Fig. 1). They are respectively called,
from the bottom to the top, the abandoned subterranean chamber
(SC), the queen’s chamber (QC), the grand gallery (GG) and the king’s
chamber (KC)—the only room built with granite stones including its
broken sarcophagus. The passage dug by al-Ma’mun in the Middle
Ages from the central axis of the pyramid to the drop stone located at
the intersection of the descending corridor (DC) and the ascending
Received: 22 September 2021
Accepted: 26 January 2023
Check for updates
1
IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France. 2
Nagoya University, 1 Furo, Chikusa, Nagoya, Aichi 464-8602, Japan. 3
PRESTO, Japan
Science and Technology Agency (JST), Saitama 332-0012, Japan. 4
Cairo University, Gamaa Street, 12613 Giza, Egypt. 5
HIP Institute, 50 rue de Rome, 75008
Paris, France. 6
Dassault Systèmes, 10 Rue Marcel Dassault, 78140 Vélizy-Villacoublay, France. 7
Whatever The Reality, 5 chemin de Picurey, 33520
Bruges, France. 8
High Energy Accelerator Research Organization (KEK), 1-1 oho, Tsukuba, Ibaraki 305-0801, Japan. 9
Emissive, 71 rue de Provence, 75009
Paris, France. 10
Université de Lorraine, CNRS, Inria, Nancy F-54600, France. 11
Ain Shams University, Kasr el-Zaafaran, Abbasiya, Cairo, Egypt. 12
These authors
contributed equally: Sébastien Procureur, Kunihiro Morishima. e-mail: sebastien.procureur@cea.fr; morishima@nagoya-u.jp
Nature Communications| (2023)14:1144 1
1234567890():,;
1234567890():,;
2. corridor (AC) is called al-Ma’mun corridor (MC) and now used as the
tourists entrance. A stone slab with a gabled structure called the
Chevron (Figs. 1 and 2a) has been located at the top of the entrance
connected to the DC made at the time the pyramid was built. This
structure is slightly excavated from the surface of the pyramid and is
thought to have been originally hidden inside the surface of the pyr-
amid. Khufu’s Pyramid is the first pyramid, in the history, that uses a
Chevron technique to cover internal structures and prevent them from
collapsing. We can find Chevron on the North Face, in the queen’s
chamber ceiling and above the king’s chamber. The construction
process of the oldest of the seven wonders of the ancient world is one
of the most important archaeological mysteries. Any discovery of
previously unknown internal structures could contribute to the
knowledge on the construction of this Pyramid.
We have investigated the internal structure of Khufu’s Pyramid
using a technique based on the observation of cosmic-ray muons.
Matter naturally absorbs a fraction of these muons coming from the
atmosphere, this fraction is determined by the thickness and by den-
sity of the probed object. The measurement of the muon flux in a given
direction then provides a direct estimate of the mean density in that
direction. From such measurements, 2D density maps can be obtained
revealing the inner structure of an object. This technique was first used
by Alvarez et al.1
for the search of hidden chambers in Khafre’s Pyramid
and has also been used for investigations of volcanoes2
and nuclear
reactors3,4
among others5
. In 2017 we discovered a large cavity named
ScanPyramids Big Void (SP-BV) using three types of muon detectors.
Fig. 1 | East-West cut view of the Great Pyramid and front view of the North face
Chevron area. a Subterranean chamber, b queen’s chamber, c grand gallery,
d king’s chamber, e descending corridor, f ascending corridor, g al-Ma’mun corri-
dor, h north face Chevron area, i ScanPyramids Big Void with horizontal hypothesis
(red hatching) and inclined hypothesis (green hatching) as published in November
20176
. All these images were obtained from a 3D modelization using dedicated laser
surveys and photogrammetry data.
a b
c d
EM1
EM7
EM3
EM4
EM5
EM6
EM2 Charpak
Joliot
Degennes
e
f g h
Fig. 2 | Detectors installedin the DC and in the MC. a The Chevron, which consists
of huge gabled limestone beams, covering the original entrance to the DC on the
North side of Khufu’s Pyramid. b 3D model and positions of the detectors from
Nagoya University, indicated by red dots and of the detectors from CEA, indicated
by orange dots, in the DC and in the MC. c–h The detectors. c shows EM3, d shows
EM2, e shows EM5, f shows Charpak, g shows Joliot and h shows Degennes.
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 2
3. In this paper, we report on the first precise analysis of the void
found with cosmic-ray muon radiography behind the North Face
Chevron and named the ScanPyramids North Face Corridor (NFC). Its
shape and location are accurately evaluated by focusing on the 7 fol-
lowing parameters: its 3 dimensions (width W, height H, length L), its
position (North-South position X, East-West position Y, altitude Z) and
its slope α. While a potential, future exploration will primarily require a
precise determination of Y and Z, most of these parameters are also
important to understand the role of the Chevron.
Results
Measurement by Nagoya University
We used nuclear emulsion films in the DC to investigate the region
behind the Chevron (Fig. 2a). Nuclear emulsion film is a photographic
film-type particle detector that can record the trajectory of a charged
particle without electric power supply. It is particularly suitable in
narrow spaces like the DC because it is compact and lightweight. A
nuclear emulsion film6
with an active area of 25 × 30 cm2
was made at
Nagoya University by coating nuclear emulsion gel to both sides of
transparent plastic base. After the observation in the DC, nuclear
emulsion films were developed in a darkroom at the Grand Egyptian
Museum Conservation Center (GEM-CC) at Cairo, and then trans-
ported to Nagoya University to be analyzed using an automated
nuclear emulsion scanning system called Hyper Track Selector
(HTS)7
. By analysing three nuclear emulsion films with measurement
period of 67 days, we reported on the discovery of NFC by detecting
an unexpected muon excess in 20168
. It seemed to be an elongated
void of at least 5 m length oriented in the North-South direction
above the DC.
From 2016 to 2019, nuclear emulsion films were installed at sev-
eral positions in the DC and MC toward the NFC to reveal the three-
dimensional shape, location and inclination of the NFC as shown in
Fig. 2. Multi-point observations from DC can provide high-resolution
images of the NFC from a short distance just below it, which can be
combined and analyzed to reveal the configuration and location of the
NFC. Multi-point observations from the MC can reveal the inclination,
location, and vertical layout of the NFC from the side. Both observa-
tions are thus complementary.
Analysis of detectors installed in the descending corridor by
Nagoya University
For the observations in the DC, detectors consisting of an aluminum
honeycomb plate mounting three nuclear emulsion films were
assembled. Six sets of detectors, respectively named EM1, EM2N,
EM2C, EM2S, EM3, and EM4, were covered by wooden boxes for pro-
tection and installed at four locations in the DC (Fig. 2). The nuclear
emulsion films were replaced periodically every few months to avoid
performance degradation9
. In this analysis, data from February to
October 2019 were used (Methods). Observed muons were analyzed
by summing different observation periods, 172 days for EM1, 211 days
for EM2 and EM3, and 79 days for EM4. The number of muon tracks
recognized within the angular range of ∣tan θx,y∣ ≦ 1.0 was 9.48 × 107
tracks for EM1, 9.39 × 107
tracks for EM2N, 2.90 × 107
tracks for EM3
and 9.87 × 106
tracks for EM4 (Methods). The observed muon flux
distributions were compared with expectations from the Geant410–12
-
based simulation framework containing the 3D model around the
Chevron and the known internal structures with the muon flux formula
given by Guan13
(Fig. 2b and Methods). Simulations were performed for
EM1 and EM2, each equivalent to an acquisition of 500 days, and for
EM3 and EM4, each equivalent to 1000 days, so that statistical fluc-
tuations from the simulations are negligible.
By comparing the observations and normalized simulations,
muon excess regions due to the NFC were clearly detected from all
detectors (EM1-EM4) and the surrounding regions were in good
agreement except around the boundaries of the 3D model (Fig. 3b). In
this analysis, the angular zone outside the region of interest and
around the edge of the 3D model was excluded.
Data normalization was performed to suppress the effects of
systematic errors due to the detection efficiency of muons on nuclear
emulsion film depending on the observation period and scanning
conditions, and to simulation conditions.
Data normalization was performed with a simulation in a region
outside the NFC by matching the mean values of the data to simula-
tions for each slice in tan θy divided by a width of tan θ = 0.025. The
muon excess significance estimated from statistical errors was well
over 10 σ (Fig. 3f).
In order to localize and estimate the dimensions of the NFC, which
was assumed to be a rectangular cuboid, simulations assuming a void
of various dimensions (width, height and length) and positions were
performed and compared with data as shown in Fig. 3a. In this analysis,
the coordinate system and its origin chosen from a specific point on
the North Face Chevron were defined, also showing the three-
dimensional structure of the NFC and its origin. The 7 parameters
chosen to characterize the NFC were obtained through χ2
analyses
from the comparison between observation and simulations (Methods).
Based on the initial analysis of path length distributions with dif-
ference between observation and simulation for rough estimation of
shape and location (Fig. 3c, d and Methods), we tentatively set the 7
parameters of dimensions (W = 2.0 m, H = 2.0 m, L = 9.5 m), location
(X = −1.0 m, Y = 0.0 m, Z = 0.5 m) and slope α = 0° to compare the data
and the corresponding simulations of each detector. The path length is
defined as the total length of the material (in this case, the stones that
construct the pyramid) existing in each direction from the detector.
Therefore, the difference between observation and simulation in the
path length will reflect the depth and shape of the NFC. As a result, a
small excess of muons was observed in all data along the periphery of
the main muon excess in the east-west direction (Fig. 3f). The amount
of small excess is equivalent to ~0.6 m of void. Therefore, we con-
sidered the possibility that a substructure with small muon excess
exists around the main structure, which is about 2 m high, and con-
ducted the subsequent analysis taking this structure into account. By
using a 2 m height for the main structure and the region where the void
is located (z > 0, x < 0) as initial conditions and comparing them with
various simulations, the parameters that determine the shape (W, H
and L) and the position (X, Y and Z) can be obtained, assuming that the
object is a single rectangular cuboid and horizontal (α = 0°). Each
parameter was evaluated by χ2
analysis in the order of X by EM2, Z, H,
W, L, and Y by EM3, by taking into account the combination of
detectors that can be determined with high accuracy (Fig. 3e and
Methods). The regions of evaluation of χ2
were determined according
to each parameter. The main structure was evaluated by considering
the influence of the sub-structure and inconsistency of entrance region
after normalization.
The shape of the NFC defined as a rectangular cuboid was esti-
mated to have a width of 2.02 ± 0.06 m, a height of 2.18 ± 0.17 m and a
length of 9.06 ± 0.07 m. The NFC appears to stop at the South side and
simulation confirmed that there is no structure with a cross section of
more than 1 m × 1 m further on the South (Fig. 3c and Methods). The
bottom plane of the NFC is located at Z = 0.72 ± 0.13 m which corre-
sponds to ~20 m from the ground level. The East-West central axis of
the NFC is located at Y = 0.03 ± 0.04 m, which is coincident with the
center of the Chevron and above the DC. The distance from the North
face of NFC to the North face of the Chevron is 0.84 ± 0.05 m which is
about the same thickness as the massive limestone block of the
chevron that can be observed from the outside, suggesting the NFC
would be located just behind it.
The possibility of the existence of sub-structures around the
main structure was evaluated against the observed results from the
DC. Using the same method as the χ2
analysis conducted to deter-
mine the parameters of the main structure, we evaluated the reduced
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 3
4. χ2
in the case that the sub-structures were added to both sides of the
main structure. Simulations were performed for two cases of sub-
structures, A: voids of 0.6 m in height and 2 m in width placed on
both sides along the main structure and B: a limestone-equivalent
with a density of 1.6 g/cm3
, which corresponds to about 73% fill for a
surrounding region with a density of 2.2 g/cm3
, occupying the region
of the same height as the main structure and 2 m in width placed on
both sides of it (Fig. 3a). The results show that the agreement
between the observed muon flux distribution and the simulation is
better for EM1, EM2N, EM3, and EM4 with the two structures, since
the reduced χ2
is smaller than that with the main structure only
(Fig. 3g). However, these two assumptions are only a subset of the
possibilities, and in the absence of constraints on the elevational
extent of the substructure, it is difficult to determine whether the
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 4
5. region contains obvious space or low-density regions with high
porosity, such as debris, along with its vertical extent.
Analysis of detectors installed in the al-Ma’mun Corridor by
Nagoya University
For the observations from the MC, four detectors (EM5, EM6H, EM6T,
and EM7) were installed in three narrow hollows on the wall of the MC,
for a total observation period of 272 days (Fig. 2). This setup allows for
observations from the sides of the NFC and the three detectors (EM5,
EM6T, and EM7) were tilted so that the observation direction points
towards the NFC (Methods).
In the MC, the detectors EM5, EM6T, and EM7 were installed with
leaning against the wall of the narrow hollows, which may cause the
detectors to change direction when they are replaced. The differences
of direction of each detector were corrected with an accuracy of 0.2°
or less by comparison between the angular distributions of muons
obtained in each observation. Through the correction process, all
observations at the same location were combined based on the first
observation period from February to April 2019 and the combined
angular distribution of muons were obtained for 272 days (Methods).
The number of muon tracks recognized within the angular range of
∣tan θy∣ ≦ 1.0 was 8.69 × 106
tracks for EM5, 8.76 × 106
tracks for EM6H,
7.38 × 106
tracks for EM6T and 1.11 × 107
tracks for EM7, respectively.
Figure 4a shows the angular distribution of the observed muon
flux divided by the flux obtained from the Monte Carlo simulation
based on Geant4, using the determined azimuthal angle from the
analysis and the 3D model excluding the DC structure. The normal-
ization of the simulation to the observation in terms of muon flux was
conducted in the same way as for the analysis of the DC in the area
outside of the NFC and not including the Chevron region (Fig. 4b). The
simulation corresponding to an observation period of 400 days was
individually performed for EM5, EM6H, EM6T, and EM7.
By comparing the data with the corresponding simulations, the
NFC was clearly detected from all detectors, with a muon excess sig-
nificance well over 10 σ, while the surrounding regions were in good
agreement except around the boundaries of the 3D model and for low
elevation angle. In addition the DC, which has a cross section of
~1 m × 1 m, is also visible for EM5, EM6T, and EM7 (Fig. 4a).
The direction pointing to the center of the NFC was determined
from each detector. Its direction was defined as the center value of the
fitting with Gaussian function of the cross-sectional distribution of the
region corresponding to the NFC by determining path length dis-
tribution from the muon flux distribution (Fig. 4c).
Since the observations from the DC confirmed that the NFC was
located just above the DC, the direction of the NFC from detectors at
the MC was projected onto a vertical plane passing through the center
of the DC (Fig. 4d and Methods). By analyzing the spatial distribution,
the NFC center in z is evaluated at 2.0 ± 0.5 m, the length is ~10 m from
behind the Chevron and the slope α is−0.3 ± 1.5° (Fig. 5b and Methods).
Comparing the data with simulations including different rectangular
cuboids with cross sections varying by 0.5 m, the best agreement was
obtained for cross sections of 1.5–2.0 m in height and 2.0–2.5 m in
width. Since this observation was conducted from the side of the NFC,
the possibility of a low-density region spreading vertically, which is not
easy to determine from a detector in the DC, was clearly eliminated.
The results from the MC are consistent with the cross-section obtained
from the DC. In the case where the substructure is attached to the main
structure, they seem to overlap in the East-West direction when
observed from the MC, so the width of the void from observations
might be larger than that of the main structure alone. The agreement
between the observations and the simulations with and without the
substructures for the main structure with a cross section of 2 m × 2 m
was evaluated, and the results were the same or better with the sub-
structures (Fig. 4a).
CEA analysis
The telescopes designed and operated by the CEA are made of micro-
pattern gaseous detectors called multiplexed Micromegas. Their
principles and performance are described in ref. 14
. Contrary to emul-
sions, such telescopes are less compact and require electricity, though
with limited power (~50 W). However the data can be processed online
with a single mini-PC, allowing for fast results. Moreover, unexpected
displacements during the acquisition can also be handled without any
loss of data. The measurement campaign started in October 2019 with
the installation of three telescopes in the DC and on a dedicated
wooden platform built at the intersection between the DC and the AC
(Fig. 2b, f–h). The middle telescope (called Joliot) had an active area of
50 × 50 cm2
, while the other two (Degennes and Charpak) were made of
two parts, resulting in a surface of 100 × 50 cm2
each. The excellent
spatial resolution of the detectors, of the order of 200 μm, yields an
angular resolution around 1 mrad only yet with very compact instru-
ments to fit in the DC. Their positions were carefully chosen to perform
a precise triangulation, Degennes telescope being also positioned to
probe the potential end of the NFC or a hypothetical connexion with
the Big Void. The 3 telescopes were flushed using a single 20 L, pres-
surized bottle of non-flamable gas (Ar-iC4H10-CF4 95-2-3) as for the
previous campaigns. Thanks to an optimized gas circuit with filtering
and recirculating units15
, the total gas consumption could be reduced
down to 0.5 L/h in steady mode. Ethernet cables were installed in the
DC to connect the 3 telescopes to a 4G router with its antenna placed
just below the Chevron. This router ensured the remote control of the
instruments from CEA in France and the transfer of the reconstructed
muon data.
All in all, the telescopes acquired about 140 days of stable data
(Methods), collecting more than 116 millions of muons. The corre-
sponding five instruments (1 + 2 + 2) were treated independently in the
analysis. The 2D raw muographies were obtained like in ref. 16
from the
angular distribution (tan(θx), tan(θy)) of the reconstructed muons (see
for example Fig. 6a). These data were compared with Geant410–12
-based
simulations of the pyramid (Methods) containing all the known
structures. To do this, a precise knowledge of the position and orien-
tation of each telescope is required. The positions were measured
in situ with a centimeter resolution and validated with the 3D model for
which a 10 cm accuracy was considered. The orientations (Euler
Fig. 3 | Results of the analysis of the nuclear emulsion films installed in the
descending corridor. a The left figure shows the 3D model of Chevron and its
origin. Center panels show the definition of the coordinate system and the origin of
the rectangular cuboid which was defined as its North extremity along x, its center
along y, and its bottom along z. Right panels show the set up of the main structure
(MS) and sub-structures designated A (SSA), B (SSB). CH denotes the Chevron.
b Two-dimensional angular distribution for EM1 to EM4. From left to right:
observed muon flux (tracks/cm2
/day/sr), 3D model, ratio of muon flux of the
observed data to simulation, with MS, with MS and SSA, with MS and SSB, and path
length with difference between the data and simulation. The resolution is tanθ =
0.025. c Histograms of path length with difference between the data and simulation
in the range of 0.000 ≦ tan θx < 0.025 in the axial direction of tanθy corresponding
to the North-South direction. d Region of existence of the NFC based on path
length. e χ2
analysis for the evaluation of parameters presenting location and shape
of the NFC. The horizontal axis shows the values of evaluated parameters. The
vertical axis is the value of reduced χ2
obtained by the comparison of the data and
simulation. f Histograms of muon flux in the range of −0.250 ≦ tanθy < −0.225 for
EM1 and EM2, 0.200 ≦ tan θy < 0.225 for EM3 and EM4, respectively. The data with
statistical error of 1 σ (standard deviation) are shown in red. The gray dashed line is
the simulation without the inner structures, the black solid line is the simulation
with the DC and MS, and the blue solid line is the simulation with the DC, MS, and
SSA. g Results of the χ2
analysis for the case where the MS and sub-structures are
added to known structures. A, B, and C denote the case where MS, MS and SSA, MS
and SSB are added, respectively.
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 5
6. Fig. 4 | Results of the analysis of the nuclear emulsion films installed in the al-
Ma’mun Corridor. a Two-dimensional angular distribution for EM5 to EM7. From
left to right: observed muon flux (tracks/cm2
/day/sr), 3D model, ratio of muon flux
of the data to simulation, with main structure (MS), with MS and sub-structure A
(SSA), with MS and sub-structure B (SSB), and path length with difference between
the data and simulation. The resolution is tanθ = 0.050. CH denotes the Chevron.
b The area used for normalization. c Left panels show two dimensional angular
distribution with enlarged area including NFC of path length difference between
the data and simulation with the resolution of tanθ = 0.025. The black dots are the
direction to the center of the NFC, obtained by taking a cross section every tan θ =
0.025 and fitting it (Methods). Center panel shows an example of path length
difference obtained by EM5, and the coordinate system is rotated to take the cross
section for fitting, which is perpendicular to the longitudinal direction (North-
South direction) of the NFC. Right panel shows an example of the fitting to a cross
section taken at tanθy = −0.1625 after rotation, which is indicated by the white line
shown in center panel, where the horizontal axis is tan θx after rotation and the
vertical axis is the difference in path length. d Location of the NFC. Left panel shows
the intersection of a vertical plane passing through the central axis of the DC and a
line extending towards the plane on the direction of the central value of the his-
togram fitted starting from the detector position. Right panel shows the result of
averaging the projection points obtained by all detectors in the height direction
with a width of 2 m in the x (North-South) direction. The error bars are the standard
deviations of the averaged projection points in the x and y directions. The red
dotted line is the approximate line obtained by linear approximation of the pro-
jection results in the range of −2 to −8 m.
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 6
7. angles) were first derived with a 1° accuracy using electronic probes
from the Yoctopuce company, and later refined down to 0.2–0.4° by a
χ2
analysis of the muon data (Methods).
An important aspect of the simulation is the choice of the cosmic
muon parametrization. Six of them were investigated, as shown in
Fig. 6b–g. As independently obtained by Nagoya analysis, the Guan
parametrization13
was found to provide the best agreement with CEA
data in terms of relative and absolute muon flux, though Bogdanova17
,
Reyna18
, and Tang19
were also close. Matsuno20
and Shukla21
deviated
significantly, but it’s worth mentioning that the former was derived for
nearly horizontal muons while the latter provided parameters at a
given muon direction, a situation not adapted to our large acceptance
instruments. Overall, data and simulation agree within 15% with the
selected parametrization except in the direction of the summit, a
region with poor statistics and out of interest for the current analysis.
Data also exhibit a mean deficit of muons in the Chevron zone due to
the higher density of the stones used in this area. Starting from the
Chevron, a very clear excess appears as a vertical line. This excess is
visible on each of the 5 muographies and corresponds to the NFC, with
a statistical significance largely above 10 σ. The excess yields about 15
muons/h for Joliot, Degennes-1 and Degennes-2, and about 60 muons/
h for Charpak-1 and Charpak-2. By the end of November 2019, the
global shape of the NFC as well as its extremities were thus well visible.
Last but not least, the NFC excess is visible with all the 6 para-
metrizations (Fig. 6b–g) and therefore cannot be attributed to any bias
from a particular one.
From the muography images and the division with simulation
(Fig. 7a–f), each instrument can provide the extremities of the NFC. To
do so, 1D histograms were obtained from thin (0.02) horizontal slices
on the 2D plots to determine the appearance and disappearance of the
NFC muon excess along the tan θy axis like in ref. 16
(Methods). These
extremities are represented by red dotted lines in Fig. 7d–f. Within
statistical errors, these extremities form cones in the x-z plane, origi-
nating from each instrument as reported in Fig. 7g.
The combination of all the cones allows to determine the extre-
mity positions by calculating the intersection points taking into
account the width of each cone. The error bars on these positions were
determined by Monte Carlo, randomly choosing a direction within
each cone (with Gaussian statistics) and calculating the corresponding
intersection points, see Fig. 8a, b. The resulting distributions of these
point coordinates directly determine the length of the NFC, i.e.
(9.23 ± 0.48) m (Fig. 8c), with a slope compatible with 0, (−1.9 + 7:2
4:7 )°
(Fig. 8d) and located on its North extremity at Z = (1.34 ± 0.53) m.
The East-West position Y of the void was accurately determined
with a set of 15 simulations per instrument using a NFC at different Y
from −8 m to −6 m. For each of these 15 × 5 simulations, a 2D histogram
was formed with tan(θy) ranging from the two determined extremities
of the NFC and with a 0.5 width in tan(θx) centered on the NFC. This 2D
histogram was then integrated in tan(θy) to form a 1D histogram in the
tan(θx) direction, whose reduced χ2
was calculated. Figure 8e shows
these χ2
values as a function of Y for the 5 instruments. The obtained
values exhibit a standard parabola shape and a fit around the minimum
provides the most likely value of Y for each instrument. As can be seen,
all the values are well compatible (see also Supplementary Table 1) and
the minimum χ2
are relatively low, except for Charpak-1 whose data
suffered from very localized noise. The statistical error bars are
obtained by considering all Y values with values from χ2
min and χ2
min+1.
In addition to the statistical error, a systematic error was taken into
account from the uncertainty on the γ angle of each instrument. A
global systematics of 10 cm was also added as the estimated precision
of the 3D geometry model. All in all, one obtains: Y = (−0.07 ± 0.04
(stat.+syst.) ± 0.10 (syst. 3D model)) m = (−0.07 ± 0.11) m. The relative
shift of the NFC compared to the DC is thus only (−7 ± 4) cm.
The same exercise was performed to determine the height H of
the NFC. The resulting χ2
values are shown in Fig. 8f and are again well
compatible (see Supplementary Table 1). In this case, an additional set
of 15 simulations per instrument was generated with a density of
2.0 g/cm3
instead of 2.2 g/cm3
in order to estimate the systematics
associated with the density uncertainty. A 10 cm difference was
observed on the mean value, leading to the following result:
H = (1.85 ± 0.07 (stat.) ± 0.10 (syst.)) m = (1.85 ± 0.12) m.
The width of the NFC was then estimated with the same method.
The results are shown in Fig. 8g and Supplementary Table 1. For each
instrument, a systematic coming from the Z position uncertainty of the
NFC (estimated to 0.5 m) should be taken into account, yieding values
from 5 to 8 cm depending on the distance of the telescopes to the NFC.
This systematic effect being fully correlated for all the telescopes, a
conservative, global systematics of 8 cm was applied, leading to:
W = (1.87 ± 0.08 (stat.) ± 0.08 (syst.)) m = (1.87 ± 0.11) m.
The same analysis was performed with pseudo-data generated
from Joliot position using the full simulation program but with scans
from the fast version. The goal was to check the absence of bias of this
analysis, by introducing a NFC and reconstructing its position and
dimensions. As illustrated on Fig. 8h, the NFC parameters were cor-
rectly reconstructed. More specifically, the reconstructed East-West
position was found to be (−0.08 ± 0.10) m (for a simulated position at
Fig. 5 | Results of the analysis of the nuclear emulsion films by Nagoya Uni-
versity. The location and shape of the NFC are shown in cross-sectional views of the
analysis area including Chevron from the North (a) and East (b) sides. Locations of
EM1 to EM4 detectors installed in the DC and obtained results are shown in red, and
EM5 to EM7 installed in the MC are shown in black, respectively in b. The red dotted
line is the projection of the location and shape of the NFC defined as a rectangular
cuboid achieved by EM1 to EM4, on planes. Black dots are the projection points in
the height obtained by detectors (EM5 to EM7) on planes and error bars, which is
the standard deviations of the averaged projection points in the x and z directions
as shown in Fig. 4d.
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 7
8. −0.12 m), the height (1.95 ± 0.22) m (for a simulated value at 2.00 m),
and the width (1.47 ± 0.21) m (simulated at 1.50 m).
While the above analysis relies on a somehow arbitrary assump-
tion that the NFC has a parallelepiped shape, this assumption is well
supported by the comparison with the simulation implementing the
fitted NFC, where the local excesses attributed to the NFC largely
disappear (Fig. 7h–j). However, it’s worth mentioning that other shapes
are compatible with data, and the chosen parallelepiped only repre-
sents the simplest possible form. If the real shape is more complex (e.g.
with a Chevron structure on the ceiling), the obtained mean dimen-
sions wouldn’t change. Last but not least, a southwards continuation of
the NFC with a smaller transverse section cannot be ruled out with the
current statistics, but simulations showed that it should then be
smaller than 1.0 m × 1.0 m to remain unseen by our instruments.
All the analyses shown up to now rely on the explicit comparison
with a 3D geometric model of the pyramid to prove the existence of
the NFC. Though the observed muon excess cannot reasonably be
attributed to any bias from this model, it is however interesting to try
imaging the NFC independently on any geometry input, only by
combining the 2D muographies in a 3D picture like in medical imaging.
We thus implemented an iterative, SART algorithm22
first applied to
images obtained with absorbed muons23
and more recently to images
obtained with transmitted ones24,25
(Methods). In spite of the small
number of projections and the enormous size of the object, this
algorithm correctly localized the NFC (Fig. 8i). The precision reached
in this case is evidently worse than the 2D analysis (as the data are not
integrated along the observation direction anymore), but this direct
reconstruction does not suffer from any systematic nor potential
errors from the 3D model, the geometry of the pyramid becoming an
output in this analysis.
Discussion
The results presented in this work were obtained by two teams using
different muon detectors and independent analyses. As can be seen in
Table 1, all the NFC parameter estimates are well compatible within
error bars, and the previously discovered NFC was measured with
excellent sensitivity. North end of the corridor starts at 0.8 m behind
the Chevron and ends at 9.1 m southward. A horizontal corridor is
Fig. 6 | Effect of the muon parametrization on the comparison between data
and simulation. a Muography of the Joliot instrument. b–g Ratio between Joliot
muography and Geant4 simulations of the known structures, using
parametrizations from Tang (b), Reyna (c), Matsuno (d), Bogdanova (e), Guan (f),
and Shukla (g).
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 8
9. Fig. 7 | NFC signal and triangulation from CEA data. a–c Raw muographies
obtained with Degennes-1, Joliot and Charpak-2. d–f Ratio between the data and the
simulation for these three instruments, showing good overall agreement except in
the summit direction where the statistics is very low. The horizontal, dashed red
lines indicate the limit of the NFC obtained by slicing each image. g Triangulation of
the NFC using the five instruments, where each cone represents the extremity of
the NFC found in one data set (i.e., the directions defined by the red lines in plots
(d–f)). The width of each cone represents the uncertainty of its direction, i.e., from
0.5 to 1.5°. The arrows show the orientation of each instrument. The yellow rec-
tangle represents the position and size of the NFC as determined from the CEA
analysis. h–j Same ratio as in d–f, obtained with a simulation containing a void
representing the NFC, whose dimensions are described in the text. The excess seen
in d–f has largely disappeared.
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 9
10. Fig. 8 | Determination of NFC characteristics from CEA data. a, b Positions of the
NFC extremities (South and North) obtained by random sampling within the
determined cones and calculation of the corresponding intersection points. The
(x;z) correlation arises from the observation direction. c, d Length and slope
obtained from this sampling, with fits of these distribution giving mean value and
error bars. e–g Results of the χ2
method to determine the East-West shift Y, the
height H and the width W of the NFC by each of the five instruments: each point
corresponds to a simulation with a different Y, H or W. The χ2
is computed on a 1D
histogram of the difference between data and simulation. The horizontal colored
lines show the statistical error bars obtained for each instrument to display the
data compatibility. h χ2
dependence as a function of Y was obtained by applying the
same analysis to pseudo-data generated with the full simulation. i Integrated
density distribution (in g/cm3
) obtained between Z = 19.5 m and Z = 23.5 m using
the SART algorithm as described in the text. The Chevron shape is correctly
reconstructed as well as the NFC position, without any geometry input.
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 10
11. favored, with a transverse section around 2.0 m × 2.0 m. More complex
shapes than a simple paralleliped are possible, but with the same mean
height and width. To our knowledge, this study is the first character-
ization of the position and dimensions of a void detected by cosmic-
ray muons with a sensitivity of a few centimeters only. On the
archaeological side, the discovery of a void located behind the Chev-
ron and having a larger cross-section than the corridors connecting the
inner structures of the pyramid may be decisive in approaching the
role of this Chevron. Last but not least, the NFC does not seem to
connect to the SP-BV, though a smaller corridor of 1.0 m between
these two structures cannot be completely ruled out from these
measurements.
Methods
Installation of nuclear emulsion films
A nuclear emulsion film which has an area of 25 cm × 30 cm was man-
ufactured, and packed with vacuum in an aluminum laminated envel-
ope for protecting light, dust and keeping humidity of films for
portability at Nagoya University6,9,16
. Nuclear emulsion films and
detector components to fix them on installation positions were sepa-
rately brought into Khufu’s Pyramid, they were assembled at installa-
tion places and the precise location of the installation has been
surveyed. By stacking two or more films at the beginning of the
observation and selecting the tracks that penetrate those nuclear
emulsion films during the observation period, the noise tracks accu-
mulated in the nuclear emulsion films and the muons recorded during
the observation were discriminated. The nuclear emulsion films were
changed every several months. The period was decided by considera-
tion of the latent image fading characteristic of them and noise track
accumulation by natural radiation from the component of kind of
stones that construct the Pyramid. The observation by nuclear emul-
sion film was started in 2015 and continued by changing the kind of
nuclear emulsion films and configurations. However the change of
nuclear emulsion films installed in November 2019 could not be con-
ducted due to COVID-19 pandemic. Observation conducted in 2019
was used for this analysis by consideration of performance of muon
detection efficiency and configuration of detectors. Two types of
detectors were used: A detector with a total thickness of 1 cm or less,
consisting of two aluminum plates of 380 mm × 310 mm × 2 or 5 mm
sandwiching two or more stacked nuclear emulsion films (Fig. 2e) and
another detector with a total thickness of 5 cm or less, consisting of two
aluminum plates of 870 mm × 300 mm × 17 mm sandwiching three sets
of two or more stacked nuclear emulsion films (Fig. 2c, d). The first,
smaller type has an effective detection area of 0.075 cm2
defined by the
size of the nuclear emulsion films and could be installed in a narrow
cavity on side wall of the al-Ma’mun Corridor (MC). The second, larger
type has an effective detection area of 0.225 cm2
which is the area of
3 sets of nuclear emulsion films and could be installed efficiently in the
descending corridor (DC), respectively. The names of the detectors in
this analysis are EM followed by the main number from 1 to 7, which is
determined by the location of the detector. The detectors with multi-
ple detectors installed at the same location were given alphabetical
sub-IDs. Specifically, EM2, in which three aluminum honeycomb
detectors were installed in the DC in a north-south direction, was
named EM2N, EM2C, and EM2S for each aluminum honeycomb
detector, starting from the north side. As for EM6, which consists of
tilted aluminum plate detectors installed on top of horizontally placed
aluminum plate detectors installed in the MC, the horizontal detectors
are named EM6H and the tilted detectors are named EM6T (Fig. 2b).
Chemical development and read out of nuclear emulsion films
The chemical development of nuclear emulsion films was conducted in
the dark room constructed in the Great Egyptian Museum Convention
Center (GEM-CC) and the films were then brought to Nagoya Uni-
versity for analysis. They were read out by the nuclear emulsion
scanning system called Hyper Track Selector (HTS) at Nagoya Uni-
versity to reconstruct the tracks which penetrated through two piled
emulsions during the data taking. Finally, muon tracks were selected
with high purity by eliminating low energy tracks, e.g. electrons, from
all the reconstructed tracks.
3D model of the pyramid and position accuracy of detectors for
nuclear emulsion films in the model
The 3D model, which includes the DC, the MC and part of the area on
the north face of the Khufu’s Pyramid containing the Chevron, was
obtained by Cairo University, HIP and Emissive (Figs. 2b and 3a).
During the scanning of the DC and the MC to create the 3D model, the
nuclear emulsion films in place at the time were also captured simul-
taneously. The origin of the 3D model for the analysis of nuclear
emulsion films was defined as the north face of the Chevron for x-axis,
the east-west center of the Chevron for y-axis, and the feature point of
the Chevron where the lower cross point of the huge gabled limestone
beams for z-axis, respectively (Fig. 3a). The positions of the detectors
in the 3D model were determined with an accuracy of 3 cm in the
north-south direction and 2 cm in the east-west direction for the DC
and 5 cm for the MC, based on the survey records during installation of
detectors and the measurements of the positions of the scanned
detectors by pointing the feature points of the detectors in the
3D model.
Simulation method for nuclear emulsion films
Two kinds of simulators were developed to estimate value of the muon
flux observed at each detector position using the Geant4 (version
10.4.2) Monte Carlo simulation toolkit10–12
. The first method is to ana-
lytically calculate the number of muons to be observed at the detector
considered as a point without area from the density length (g/cm2
)
defined as the path length (cm) multiplied by the density (g/cm3
) in
each direction, which is obtained from the detector position in the 3D
model, and is referred to as a simplified fast simulation. The second
method is a Monte Carlo simulation that incorporates a muon gen-
erator that takes into account the muon energy distribution, angular
distribution, irradiation region and detector area. The 3D model was
converted to GDML format, which is commonly used in Geant4, for the
simulation. The simple simulation takes a few seconds to calculate the
angular distribution of the muon flux for a single condition. In order to
determine the conditions for the simulation, the simplified fast simu-
lation were performed under a combination of different densities of
stones made of the Pyramid (1.8 g/cm3
to 2.6 g/cm3
at 0.2 g/cm3
intervals) and nine different muon flux models (Miyake26
(integration
and differentiation), Jockich27
(integration and differentiation),
Bogdanava17
, Reyna18
, Tang19
, Guan13
, and Sato28,29
). The angular dis-
tributions of each simulation and observation were compared to each
other in the region excluding the NFC. Among the evaluated condi-
tions, the simulation result using the Guan model with a pyramid
density of 2.2 g/cm3
provided the best agreement with the data, so the
Table 1 | Summary of the NFC characteristics
Parameter Nagoya estimate CEA estimate
Width W (m) 2.02 ± 0.06 1.87 ± 0.11
Height H (m) 2.18 ± 0.17 1.86 ± 0.12
Length L (m) 9.06 ± 0.07 9.23± 0.48
North-South X (m) 0.84 ± 0.05 0.45 ± 0.22
East-West Y (m) 0.03 ± 0.04 −0.07 ± 0.11
Altitude Z (m) 0.72 ± 0.13 1.34 ± 0.53
Slope α (°) −0.3 ± 1.5 −1.9 + 7:2
4:7
Dimensions, positions, and orientation were obtained independently by Nagoya and CEA ana-
lyses. The East-West shift is taken from the descending corridor. X is positive for South. Y is
positive for West.
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 11
12. simulations were performed in these conditions. This result can be
interpreted as the fact that the Guan equation best describes the
angular dependence of the energy distribution in the low energy
region among the compared models. Parameters for running simula-
tion and resolution of 3D model were decided to achieve a reasonable
speed of the Monte Carlo simulation as described below. The mini-
mum energies of muon to be exposed in the simulation were set to 0.2
GeV for EM1, 0.5 GeV for EM2, 1 GeV for EM7, 3 GeV for EM5, EM6 and
EM7, and 5 GeV for EM3 and EM4, by considering minimum energy of
muons passed through pyramid to each detectors. Muons were irra-
diated in the angle range of 0–60° (−1.73 ≦ tan θ ≦ 1.73) from the axis
perpendicular to the detector surface and in an area slightly larger than
the detector area, by taking into account the effect of scattering of
muons while passing through the pyramid and angular range for
analysis to avoid inefficiency of muon exposure. Electromagnetic
process and decay process in terms of physical interactions are com-
puted and only muons are traced in the simulation. The Monte Carlo
simulations under these conditions took about a day to perform on a
PC configured with an AMD Ryzen Threadripper 3970X 3.7 GHz 32
cores/64 threads, which is equivalent to 100 days of calculations in
terms of real-world observation time.
Data correction of the nuclear emulsion films installed in the
descending corridor
The analyzed data are from detectors installed at four locations at the
DC on five separate occasions (Feb. to Apr., Apr. to Jun., Jun. to Jul., Jul.
to Sep., Sep. to Oct.) from February to October 2019. The recon-
structed muon tracks were integrated for four observations (equiva-
lent to 172 days) for EM1, five observations (211 days) for EM2 and EM3,
and two observations (79 days) for EM4.
Estimation of path length by the analysis of the nuclear emul-
sion films installed in the descending corridor
The density length was calculated by using the formula of muon flux
given by Guan13
and the relationship between muon energy and flight
length in the case of the limestone density assumed 2.2 g/cm3
based on
the table given by GROOM et al.30
. The path length was calculated by
dividing the density length by the density of 2.2 g/cm3
(Fig. 3b, c).
Initial analysis of the NFC by the nuclear emulsion films installed
in the descending corridor
Distributions of the path length with the difference between observed
data and simulation, which corresponds to length of the NFC along the
line of sight in the axial direction of tan θy, are shown in Fig. 3c. The
distributions of the path length by all detectors are consistent and it’s
value is ~2 m. The directions corresponding to the northern and
southern ends of the NFC were identified if they were within the
observed field of view. By checking the range where they intersect in
three dimensions, we estimated the angular range and location where
the NFC exists (Fig. 3d). The NFC is located in the angular region of
tan θy = −0.1125 or less by EM1, tan θy = −0.0125, 0.0375 and 0.0875 or
less by EM2N, EM2C and EM2S, and between of 0.0125 ≦ tan θy 0.6625
by EM3 and 0.1125 ≦ tan θy 0.7125 by EM4, in tan θy coordinate,
respectively. The estimated location in height is above 0 m in z.
χ2
analysis and parameter estimation accuracy by the nuclear
emulsion films installed in the descending corridor
The evaluation area of reduced χ2
were −0.05 ≦ tan θx 0.05,
−0.2 ≦ tan θy 0.2 for X, −0.15 ≦ tan θx 0.15, 0.1 ≦ tan θy 0.4 for Y
and W, −0.05 ≦ tan θx 0.05, 0.4 ≦ tan θy 0.8 for Z, −0.05 ≦
tan θx 0.05, 0.1 ≦ tan θy 0.4 for H, and −0.05 ≦ tan θx 0.05,
−0.2 ≦ tan θy 0.1 for L. Simulations for the χ2
evaluation corre-
sponded to 500 days of observations for X, 400 days for Y, W and L,
800 days for Z and 200 days for H. For the evaluation of X (location of
the northern extremity), the data and simulations were normalized for
a region of −0.3 ≦ tan θx −0.2, 0.2 ≦ tan θx 0.3 for each slice in tan θy
divided by a width of tan θ = 0.025 for EM2. For the evaluation of Z, W
and Y, the data and simulations were normalized for a region of
−0.2 ≦ tan θx −0.15, 0.15 ≦ tan θx 0.2 for each slice in tan θy divided
by a width of tan θ = 0.025 to suppress the influence of small excess
due to sub-structure, for EM3. For the evaluation of H, the data and
simulations were normalized for a region of −0.5 ≦ tan θx −0.2,
0.2 ≦ tan θx 0.5 for each slice in tan θy divided by a width of tan θ =
0.025 for EM3. Assuming a void model of a single horizontal rectan-
gular solid, the value of χ2
/ndf was derived by comparing observations
with simulations in which the numerical value of one of the parameters
under evaluation was changed. By fitting five values including the
minimum value of χ2
/ndf in the evaluated parameters with a quadratic
function, a value of the parameter with the minimum χ2
/ndf was
obtained, and the statistical error of the decision accuracy was deter-
mined (Fig. 3e). The validity of the χ2
analysis was evaluated using the
simulation based on Geant4 and its accuracy was estimated to be a few
cm, except for Z. Since the value of Z was evaluated by normalizing to
the region containing the sub-structure, the small excess of muons due
to it would cause a systematic shift on the Z position of the main
structure. The effect was estimated by a simulation with the sub-
structures and Z was estimated to be 0.45 m ± 0.05 m higher than the
input location. This systematic shift was included in the parameter
estimate. Furthermore, a 10% variation in pyramid density, assumed to
be 2.2 g/cm3
in this analysis, yielded a systematic error of 0.16 m in H.
The effect of secondary electrons generated when cosmic rays pene-
trate the stone material of the pyramid was estimated to be up to 1.5%
on H. Other systematic errors were estimated to take into account the
3D model accuracy, the detector positioning in the 3D model, the
accuracy of installation of the detectors, and propagation of error by
the evaluation order. These evaluations lead to the following esti-
mates: X = 0.84 ± 0.02(stat) ± 0.05(syst) m, W = 2.02 ± 0.05(stat) ±
0.03(syst) m, H = 2.18 ± 0.04(stat) ± 0.16(syst) m, L = 9.06 ± 0.05(stat) ±
0.05(syst) m, Z = 0.72 ± 0.08(stat) ± 0.11(syst) m and Y = 0.03 ±
0.02(stat) ± 0.03(syst) m. The systematic error on H includes a density
variation of 10%.
Estimation of the southward stopping position of NFC and its
cross-sectional shape
An estimation was conducted to determine how far the NFC continues
to the south (Fig. 3c). Simulations for two void models with cross
sections of 2 m × 2 m and 1 m × 1 m for EM3 were performed, and it
was estimated that those voids can be detected significantly beyond
tan θy = 0.0 to about −0.3. Therefore, there is no structure with a cross
section larger than 1 m × 1 m in the south, further than the direction
where the NFC appears to stop.
Data correction of the nuclear emulsion films installed in the al-
Ma’mun Corridor
The analyzed data were obtained from the detectors installed at three
locations in the al-Ma’mun corridor on six separate terms (Feb. to Apr.,
Apr. to Jun., Jun. to Jul., Jul. to Sep., Sep. to Oct., Oct. to Nov.) from
February to October 2019. The reconstructed muon tracks were inte-
grated for six observations (equivalent to 272 days) for all detectors
(EM5, EM6H, EM6T, and EM7).
Data integration of the nuclear emulsion films installed in the al-
Ma’mun corridor
A systematic deviation was seen in the comparison of angular dis-
tribution of the muon flux between the observation and simulation
with the initial azimuth angle. This deviation is likely due to a differ-
ence between the azimuth angle measured by the analog compass
during the survey and the actual value from the compass near the
magnetic material used to construct the detectors. Therefore, a com-
parison was conducted between the observation and the simulations
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 12
13. by simplified fast simulation with azimuth angle of the detector vary-
ing in 0.5° increments at a density of 2.2 g/cm3
, in order to find the
angle providing the best angular distribution agreement.
Calibration of the azimuthal angle of the nuclear emulsion films
installed in the al-Ma’mun corridor
The agreement between observed and simulated angular distribution
was evaluated from the standard deviation of the differences of the
value in each bin in the angular range including the structures around
the Chevron because of the regions with large changes in the undu-
lations of the shape are effective to determine the direction of the
detectors. The regression curve was calculated using the azimuthal
dependence of the standard deviation in the region evaluated in 0.5°
increments, and the azimuthal angle with the minimum standard
deviation in 0.1° increments was determined.
Projection analysis by the nuclear emulsion films installed in the
al-Ma’mun corridor
The distribution of differences between observation and simulation of
path length corresponds to the superimposed distribution of the
structure of the NFC (Fig. 4a, c). The direction distribution of maximum
of path length differences is considered to be indicated the distribution
of center of the NFC in the case of simple structure. The location of the
center of the NFC in height was estimated by projecting the direction of
maximum direction of path length differences, which corresponds to
the NFC, to the vertical plane on the center axis of the DC, because the
location of the NFC is considered to be just above the DC from the
results of the detectors installed in the DC. The projected direction was
determined by making the histogram of a cross section of the angular
distribution, which is perpendicular to the longitudinal direction
(north-south direction) of the NFC, and fitting each histogram by a
Gaussian function to obtain the center value (Fig. 4c). Figure 4d shows
the intersection of a vertical plane passing through the central axis of
the DC and a line extending towards the plane in the direction of the
central value of the histogram fitted starting from the detector posi-
tion. The location of the centre of the NFC was determined to be
2.0 ± 0.5 m using a range of −2 to −8 m in the x corresponding to north-
south direction by eliminating the area which included the outer part of
the NFC to avoid the effect of pointing in the wrong direction (Fig. 5b).
Errors were estimated by standard deviation of distribution in height
and they are reasonable values considering the accuracy of determi-
nation of the detector position in the 3D model, systematic errors of
the projection method, and errors due to fitting. The slope of the NFC
in north-south direction was calculated by linear approximation using
the least squares method for the same range of estimation of location
in height, and was estimated to be (−0.3 ± 1.5)°. The length of the NFC
was estimated to be ~10 m in maximum and it appears to stop at the
south side from starting at just behind the Chevron.
Installation and operation of the CEA telescopes
The 3 telescopes were installed from Oct. 19th to 22nd, 2019. After
sufficient gas flushing, the acquisition started on Oct. 19th on
Degennes, and Oct. 25th on Joliot and Charpak. All the telescopes
showed excellent and stable performance (see Supplementary Fig. 1).
They all stopped on March 13th 2020 after an electricity cut due to a
storm. Charpak was restarted on March 18th at a reduced gas flow, and
definitely stopped on April 6th following the COVID-19 pandemic. All
in all, Degennes and Joliot accumulated about 140 days of stable data,
and Charpak around 158 days, yielding respectively 29.8, 13.0 and 73.4
millions of good muons.
CEA simulation
The 3D CAD model used in the simulations was obtained by Cairo
University, HIP and Emissive, and is therefore identical to the one used
by Nagoya. To speed up the simulation time, parametrizations of all
the important phenomena (energy loss, straggling and multiple scat-
tering) were derived from Geant4, so that muons can be simulated
without the whole, time consuming Geant4 propagation in the pyr-
amid. This fast Monte Carlo used a 2D distance map generated for each
telescope position. While the full Geant4 simulation takes about
50 days to produce the equivalent of 100 days of data taking, the fast
simulation requires only 3 min on a standard laptop. The 2D muo-
graphies obtained from the Joliot position by the fast and the full
Monte Carlo simulations (using only muons and no secondary elec-
trons) were compared and showed no significant difference (see
Supplementary Fig. 2).
Analysis of the telescopes data
The 2D raw muographies were obtained for each instrument from the
reconstruction of muon trajectories requiring a signal in at least 3
detectors out of 4. Thanks to this redundancy, the small detector
inefficiency (5%) can be safely neglected. A precise comparison with
the simulation then required the determination of telescope orienta-
tions, defined by Euler angles. The rotation around vertical axis (α) was
very precisely fixed by aligning the telescopes with the DC and AC
corridors, allowing for the telescopes to be aligned in the North-South
axis with a precision of about 0.2° (2 cm accuracy over the 60 cm
telescope length). The 2 other angles β (rotation around East-West
axis) and γ (rotation around North-South axis) were measured with a 1°
accuracy. For each of the 5 instruments, a set of 15 simulations were
performed at different values of β and 15 others at different values of γ.
For each of them, the 2D muography ratio between data and simula-
tion was computed. For the scan in β (resp. γ), a 1D histogram was then
formed along the tan(θy) (resp. tan(θx)) axis by integrating in a wide
range of tan(θx) (resp. tan(θy)). In both cases, the NFC zone was
excluded from the scanned region not to bias the result. The γ scan is
illustrated in Supplementary Fig. 3 for Degennes telescope. The χ2
of
each 1D histogram is then calculated as a function of β and γ to
determine the best value. Such a comparison allows for a determina-
tion of these angles with a 0.2 to 0.4° accuracy.
Once the position and orientation of all telescopes are precisely
adjusted, the comparison between data and simulation in the NFC
region provides its extremities as seen by each instrument. Supple-
mentary Fig. 4 shows an example of the horizontal slicing performed
on the 2D muography of Degennes-Q2. The North extremity is thus
observed at tan(θy)= 0.49 ± 0.01, the same exercise at the South side
leading to tan(θy)= 0.11 ± 0.01.
3D reconstruction with SART algorithm
An alternative way to reconstructa structure like the NFC is to combine
the 2D muographies to obtain a 3D tomographic image. This method is
routinely used in medical imaging, but with many more projections
and a lot more of statistics. Following a first implementation of the
SART algorithm in the special mode of absorption muography23
, a
procedure was developed to apply it to all the CEA data taken inside
the pyramid (representing 11 sets of data). The volume to image is
splitted into Nv 3D pixels (or voxels), and each of the n data set i (a
dataset is a 2D muography) is separated in ni
m independent measure-
ments. The aim is then to solve the following equation:
½Aρ = O, ð1Þ
where ρ is the unknown density Nv-vector, representing the density in
each voxel, O is the opacity vector, of size Nm=
P
ini
m, and [A] is the
distance matrix whose element (k,l) contains the mean distance tra-
veled in the lth
voxel by muons from the kth
opacity measurement.
This distance matrix can be calculated once the voxels and the data
splitting have been chosen. But on the contrary to the absorption
mode23
, the opacity cannot not be directly obtained from the data
alone. An open-sky simulation at each telescope position should first
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 13
14. be performed in order to get the muon flux in each ni
m measurement,
and therefore the muon absorption factor. An additional set of
Geant4-based simulations are then generated using different
thicknesses of materials, to parametrize the relation between the
opacity and the muon absorption factor. The muon energy distribu-
tion being dependent on the azimutal angle, this parametrization is
angle dependent24
.
Once the opacity vector is determined, the SART algorithm
iteratively updates the vth
voxel density by adding the following value
at iteration n + 1:
Δρn + 1
v =
PNm
m = 1 wm
OmOn
m
Am
!2
PNm
m = 1 wm
× Am,v,
ð2Þ
with On
m being defined as:
On
m =
X
Nv
v = 1
Om, vρn
v , ð3Þ
and wm is a weight coming from the statistics in the mth
measurement.
The volume to image was chosen to be a parallelepiped of size
230 × 230 × 140 m3
thus containing the whole pyramid, with 1 × 1 × 1 m3
voxels. The 11 data sets were each splitted in 100 × 100 measurements,
resulting in a distance matrix with about 814 billion elements. The
density vector is initiated using a perfect, full pyramid of density
2.0 g/cm3
, thus without any inside or outside structures. The result
shown in Fig. 8i is obtained after the equivalent of 150,000 iterations,
and represents the density distribution in a slice between z = 19.5 and
23.5 m above the ground in the vicinity of the Chevron. In spite of the
enormous size of the system to be solved, the algorithm correctly
identifies a strong under-density and the overall shape of the Chevron
zone with its East-West asymetry, as well as an under-density corre-
sponding to the NFC. Because of the limited resolution in the z axis, the
under-density is diffused over about 5 m high, and the NFC height
cannot be fully resolved by this technique. Though less precise than
the 2D triangulation performed above, this procedure does not require
any precise geometrical model of the object to image, as this geometry
becomes an output of the analysis.
Data availability
The raw data that support the findings in this study are available from
the corresponding authors. Please note that the data sharing should be
approved by the Egyptian Ministry of Antiquities. The project coordi-
nator (Prof. H. Helal) is responsible for the communication with the
Ministry regarding this point.
Code availability
The analysis code that supports the findings in this study are available
on reasonable requests from the corresponding authors.
References
1. Alvarez, L. et al. Search for hidden chambers in the pyramids. Sci-
ence 167, 832–839 (1970).
2. Tanaka, H. et al. Development of an emulsion imaging system for
cosmic-ray muon radiography to explore the internal structure of a
volcano, Mt. Asama. Nucl. Instrum. Methods Phys. Res. A 575,
489–497 (2007).
3. Morishima, K. et al. First demonstration of cosmic ray muon radio-
graphy of reactor cores with nuclear emulsion based on an auto-
mated high-speed scanning technology. Proc. 26th Workshop on
‘Radiation Detectors and Their Uses’27–36 (2012).
4. Fujii, H. et al. Performance of a remotely located muon radiography
system to identify the inner structure of a nuclear plant. Progr.
Theor. Exp. Phys. 7, 073C01 (2013).
5. Procureur, S. Muon imaging: Principles, technologies and applica-
tions. Nucl. Instrum. Methods Phys. Res. A 878, 169–179 (2018).
6. Morishima, K. et al. Development of nuclear emulsion for muo-
graphy. Ann. Geophys. 60, 0112 (2017).
7. Yoshimoto, M. et al. Hyper-track selector nuclear emulsion readout
system aimed at scanning an area of one thousand square meters.
Prog. Theor. Exp. Phys. 10, 103H01 (2017).
8. Scanpyramids - first conclusive findings with muography on khufu
pyramid. http://www.hip.institute/press/HIP_INSTITUTE_CP9_EN.
pdf (2016).
9. Nishio, A. et al. Nuclear emulsion with excellent long-term stability
developed for cosmic-ray imaging. Nucl. Instrum. Methods Phys.
Res. A 966, 163850 (2020).
10. Agostinelli, S. et al. geant4 - a simulation toolkit. Nucl. Instrum.
Methods Phys. Res. A 506, 250–303 (2003).
11. Allison, J. et al. Geant4 developments and applications. IEEE Trans.
Nucl. Sci. 53, 270–278 (2006).
12. Allison, J. et al. Recent developments in geant4. Nucl. Instrum.
Methods Phys. Res.A 835, 186–225 (2016).
13. Guan, M. et al. A parametrization of the cosmic-ray muon flux at sea-
level. https://arxiv.org/abs/1509.06176 (2015).
14. Bouteille, S. et al. Large resistive 2d micromegas with genetic
multiplexing and some imaging applications. Nucl. Instrum. Meth-
ods Phys. Res. A 834, 187–191 (2016).
15. Procureur,S.et al. Why do we flush gas in gaseous detectors?. Nucl.
Instrum. Methods Phys. Res. A 955, 163290 (2020).
16. Morishima, K. et al. Discovery of a big void in khufu’s pyramid by
observation of cosmic-ray muons. Nature 552, 386–390 (2017).
17. Bogdanova, L. et al. Cosmic muon flux at shallow depths under-
ground. Phys. Atomic Nuclei 69, 1293–1298 (2006).
18. Reyna, D. A simple parameterization of the cosmic-ray muon
momentum spectra at the surface as a function of zenith angle.
Preprint at https://arxiv.org/abs/hep-ph/0604145 (2006).
19. Tang, A. et al. Muon simulations for super-kamiokande, kamland,
and chooz. Phys. Rev. D 74, 053007 (2006).
20. Matsuno, S. et al. Cosmic-ray muon spectrum up to 20 tev at
89degree zenith angle. Phys. Rev. D 29, 1 (1984).
21. Shukla, P. Sankrith, S. Energy and angular distributions of atmo-
spheric muons at the earth. Int. J. Modern Phys. A 33,
1850175 (2018).
22. Kak, C. et al. Principles of computerized tomographic imaging.
Med. Phys. 29, 107 (2002).
23. Baccani, G. Muon absorption tomography of a lead structure
through the use of iterative algorithms. JINST 15, P12024 (2020).
24. Procureur, S. Muon tomography of large structures with 2d pro-
jections. Nucl. Instrum. Methods Phys. Res. A 1013, 165665 (2021).
25. Baccani, G. Development, testing and application to real case stu-
dies of a three-dimensional tomographic technique based on muon
transmission radiography (phd thesis) (2021).
26. Miyake, S. Rapporteur paper on muons and neutrinos. Proc. 13th Int.
Cosmic Ray Conf. 5, 3638–3655 (1973).
27. Jokisch, H. et al. Cosmic-ray muon spectrum up to 1 tev at 75° zenith
angle. Phys. Rev. D 19, 1368 (1979).
28. Sato, T. et al. Analytical model for estimating terrestrial cosmic ray
fluxes nearly anytime and anywhere in the world: Extension of
parma/expacs. PLoS ONE 10, e0144679 (2015).
29. Sato, T. et al. Analytical model for estimating the zenith angle
dependence of terrestrial cosmic ray fluxes. PLoS ONE 11,
e0160390 (2016).
30. GROOM, D. et al. Muon stopping power and range tables 10 mev-
100 tev. At. Data Nucl. Data Tables 78, 183–356 (2001).
Acknowledgements
Special thanks are due to the Egyptian Ministry of Tourism and Anti-
quities for permitting the work of ScanPyramids mission in cooperation
Article https://doi.org/10.1038/s41467-023-36351-0
Nature Communications| (2023)14:1144 14