This document describes a study that uses data from the 2MASS galaxy catalog and galaxy merger rates from the Illustris simulation to construct probabilistic models of the local nanohertz gravitational wave landscape detectable by pulsar timing arrays. It finds an average of 91±7 ongoing supermassive black hole binary mergers within 225 Mpc emitting continuous gravitational waves. Using all-sky gravitational wave sensitivity maps, it estimates that at least one of these sources could be detected within 10 years with current pulsar timing arrays. Accounting for the positions of the best pulsars, the sensitivity is increased by a factor of 4, detecting more sources.
The Cosmic Microwave (CMB), and Infra-Red (CIRB) Backgrounds are Simple Effec...David Harding
In Continuous Quantum Iteration (CQI) theory, a new approximation of the universal engagement is explored. Science, as of yet, cannot define infinity; the absolute beginning. Yet it is only natural that science should ask the question....How did the local Universe get started? And where does this energy keep coming from? And what is the quantum vacuum really doing? Aspects of virtual quantum iteration are examined considering the plausibility of this new approximation. The Cosmic Microwave (CMB), and the Infra-Red Background (CIRB) are shown to be simple effects of Continual Quantum Vacuum Iterations occurring through Planck-Stoney scale interactions with the universal equilibrium event - horizon background.
This document summarizes cosmological parameters measured from galaxy surveys. It discusses:
1) Direct measurements of the Hubble constant from the Hubble Space Telescope and Planck, finding values of 72-74 km/s/Mpc and 67.3 km/s/Mpc respectively.
2) Supernova surveys finding evidence for an accelerating universe with matter density of ~30% and dark energy density of ~70%.
3) Measurements of cosmic microwave background from COBE, WMAP and Planck, determining ages and densities of the universe.
4) Galaxy clustering surveys like SDSS detecting baryon acoustic oscillations to measure dark energy properties.
Gwendolyn Eadie: A New Method for Time Series Analysis in Astronomy with an A...JeremyHeyl
1. The document describes a new method called Multitaper + Lomb-Scargle (MTLS) for estimating the power spectrum of unevenly sampled time series data, such as that from astronomical observations.
2. MTLS combines the Multitaper method, which reduces spectral leakage and variance, with the Lomb-Scargle method, which can handle uneven sampling times.
3. The document provides an example application of MTLS to estimate the power spectrum of a red giant star using Kepler telescope lightcurve data, finding an improvement over the standard Lomb-Scargle method.
The document discusses separating gravitational redshift from cosmic expansion redshift in observed cosmic microwave background radiation. It presents calculations of curvature ratios at different points in the early universe, such as at electroweak symmetry breaking and at the surface of last scattering. Taking the curvature ratio at these two points and using observed CMB redshift of 1091, the analysis estimates gravitational redshift would be around 2-3, with most of the observed redshift coming from cosmic expansion. This has implications for the energy density and relativistic nature of the early universe.
1) The document discusses using the effective one body (EOB) formalism to model gravitational wave templates for LIGO and LISA. It summarizes the number and type of templates used in LIGO's first two observing runs.
2) It also discusses using EOB, post-Newtonian theory, numerical relativity simulations, and quantum field theory to model gravitational wave emission from binary black hole and binary neutron star mergers across different mass ratio and velocity regimes.
3) The document focuses on recent work extending EOB models to higher post-Minkowskian orders and including the effects of spin and tidal interactions, with the goal of more accurate gravitational wave template modeling.
1) Pulsar timing arrays are searching for gravitational waves from massive black hole binaries in the nanohertz frequency range.
2) Current pulsar timing array efforts have not detected a gravitational wave signal but are placing increasingly stringent upper limits.
3) Future and more sensitive radio telescopes like FAST, MeerKAT, and the Square Kilometre Array will improve the prospects for a direct detection of gravitational waves from massive black hole binaries within the next decade.
1) The document discusses multi-messenger astronomy and the detection of electromagnetic counterparts to gravitational waves, neutrinos, and cosmic rays.
2) It provides background on neutrino astronomy, gravitational wave detections from binary neutron star mergers, and kilonova emissions from such mergers.
3) The merger of GW170817 and its association with GRB170817A and kilonova AT2017gfo provided the first direct evidence that neutron star mergers are the origin of short gamma-ray bursts and produce r-process nucleosynthesis.
Alessandra Buonanno gave a lecture on the analytical and numerical relativity approaches used to model gravitational waveforms from inspiraling binary systems. She discussed how post-Newtonian theory, effective one body theory, and numerical relativity are used to approximately and exactly solve Einstein's field equations. She emphasized the crucial synergy between analytical and numerical relativity approaches to develop accurate gravitational waveform models like EOBNR and Phenom that have been used to infer astrophysics from LIGO/Virgo detections.
The Cosmic Microwave (CMB), and Infra-Red (CIRB) Backgrounds are Simple Effec...David Harding
In Continuous Quantum Iteration (CQI) theory, a new approximation of the universal engagement is explored. Science, as of yet, cannot define infinity; the absolute beginning. Yet it is only natural that science should ask the question....How did the local Universe get started? And where does this energy keep coming from? And what is the quantum vacuum really doing? Aspects of virtual quantum iteration are examined considering the plausibility of this new approximation. The Cosmic Microwave (CMB), and the Infra-Red Background (CIRB) are shown to be simple effects of Continual Quantum Vacuum Iterations occurring through Planck-Stoney scale interactions with the universal equilibrium event - horizon background.
This document summarizes cosmological parameters measured from galaxy surveys. It discusses:
1) Direct measurements of the Hubble constant from the Hubble Space Telescope and Planck, finding values of 72-74 km/s/Mpc and 67.3 km/s/Mpc respectively.
2) Supernova surveys finding evidence for an accelerating universe with matter density of ~30% and dark energy density of ~70%.
3) Measurements of cosmic microwave background from COBE, WMAP and Planck, determining ages and densities of the universe.
4) Galaxy clustering surveys like SDSS detecting baryon acoustic oscillations to measure dark energy properties.
Gwendolyn Eadie: A New Method for Time Series Analysis in Astronomy with an A...JeremyHeyl
1. The document describes a new method called Multitaper + Lomb-Scargle (MTLS) for estimating the power spectrum of unevenly sampled time series data, such as that from astronomical observations.
2. MTLS combines the Multitaper method, which reduces spectral leakage and variance, with the Lomb-Scargle method, which can handle uneven sampling times.
3. The document provides an example application of MTLS to estimate the power spectrum of a red giant star using Kepler telescope lightcurve data, finding an improvement over the standard Lomb-Scargle method.
The document discusses separating gravitational redshift from cosmic expansion redshift in observed cosmic microwave background radiation. It presents calculations of curvature ratios at different points in the early universe, such as at electroweak symmetry breaking and at the surface of last scattering. Taking the curvature ratio at these two points and using observed CMB redshift of 1091, the analysis estimates gravitational redshift would be around 2-3, with most of the observed redshift coming from cosmic expansion. This has implications for the energy density and relativistic nature of the early universe.
1) The document discusses using the effective one body (EOB) formalism to model gravitational wave templates for LIGO and LISA. It summarizes the number and type of templates used in LIGO's first two observing runs.
2) It also discusses using EOB, post-Newtonian theory, numerical relativity simulations, and quantum field theory to model gravitational wave emission from binary black hole and binary neutron star mergers across different mass ratio and velocity regimes.
3) The document focuses on recent work extending EOB models to higher post-Minkowskian orders and including the effects of spin and tidal interactions, with the goal of more accurate gravitational wave template modeling.
1) Pulsar timing arrays are searching for gravitational waves from massive black hole binaries in the nanohertz frequency range.
2) Current pulsar timing array efforts have not detected a gravitational wave signal but are placing increasingly stringent upper limits.
3) Future and more sensitive radio telescopes like FAST, MeerKAT, and the Square Kilometre Array will improve the prospects for a direct detection of gravitational waves from massive black hole binaries within the next decade.
1) The document discusses multi-messenger astronomy and the detection of electromagnetic counterparts to gravitational waves, neutrinos, and cosmic rays.
2) It provides background on neutrino astronomy, gravitational wave detections from binary neutron star mergers, and kilonova emissions from such mergers.
3) The merger of GW170817 and its association with GRB170817A and kilonova AT2017gfo provided the first direct evidence that neutron star mergers are the origin of short gamma-ray bursts and produce r-process nucleosynthesis.
Alessandra Buonanno gave a lecture on the analytical and numerical relativity approaches used to model gravitational waveforms from inspiraling binary systems. She discussed how post-Newtonian theory, effective one body theory, and numerical relativity are used to approximately and exactly solve Einstein's field equations. She emphasized the crucial synergy between analytical and numerical relativity approaches to develop accurate gravitational waveform models like EOBNR and Phenom that have been used to infer astrophysics from LIGO/Virgo detections.
This document summarizes a lecture on using gravitational wave waveform models to test general relativity and probe the nature of compact objects through gravitational wave observations. It discusses how waveform models can be used to bound post-Newtonian coefficients, constrain phenomenological merger-ringdown parameters, and probe the quasi-normal modes of black hole ringdowns. Measuring multiple modes could verify the no-hair theorem and black hole uniqueness properties. Future observations from LIGO and Virgo at design sensitivity may allow high-precision black hole spectroscopy and tests of general relativity in the strong, dynamical gravity regime.
1. The document discusses potential low frequency gravitational wave sources that could be detected by LISA, including galactic white dwarf binaries, massive black hole binaries, and extreme mass ratio inspirals.
2. LISA could detect thousands of massive black hole binaries and provide precise measurements of their parameters like mass and spin, enabling tests of general relativity and learning about black hole formation mechanisms.
3. Extreme mass ratio inspirals where a compact object spirals into a massive black hole could occur at a rate of 10-7 per year in our galaxy, allowing precision cosmology and tests of the no-hair theorem.
This document provides an overview of dimuon analyses at the LHC and discusses big data challenges. It outlines the Standard Model and motivations for new physics searches. The CMS detector is described, focusing on muon reconstruction challenges. Data selection and efficiency measurements are discussed. The analysis philosophy of searching for a narrow resonance over the Drell-Yan continuum is presented.
1) Massive black hole binaries form during galaxy mergers and evolve through dynamical friction and 3-body interactions with stars until reaching separations of ~0.01 pc where gravitational wave emission takes over.
2) Gas dynamics may also drive black hole binaries to smaller separations for coalescence.
3) Black hole binary coalescence timescales are typically long, on the order of billions of years, which has implications for gravitational wave detection and triple black hole interactions.
A. De Simone: The Quest for Dark Matter: Update and NewsSEENET-MTP
The document summarizes the status of dark matter searches from multiple experiments and detection strategies. It discusses evidence that dark matter exists from cosmological measurements and observations of galaxy rotations. It also outlines various dark matter candidate particles and the search strategies used, including direct detection experiments that have seen some positive hints of an annual modulation signal including DAMA/Libra and CoGeNT experiments, but are in tension with null results from Xenon, CDMS, and Edelweiss experiments. Collider searches for dark matter are also discussed.
The document discusses gravitational waves and binary systems. It provides context on the history of gravitational wave detection, from Einstein's early work developing the theory of gravitational waves to Joseph Weber's pioneering efforts to detect them in the 1960s. It also summarizes the development of laser interferometer gravitational wave detectors by researchers in the US, Germany, Italy, and the UK beginning in the 1970s and 1980s. Key detections by LIGO and Virgo are noted, including GW150914 in 2015. Theoretical work on modeling gravitational waveforms from coalescing compact binaries is summarized, from early perturbative approaches to more recent analytical methods like the effective one-body formalism.
This document proposes that dark energy may be an artifact of the free energy required to encode classical information about quantum systems into the environment. It applies the framework of quantum Darwinism to model how the positions of stars are encoded in the ambient photon field. Assuming Landauer's principle, encoding the positions of 10^25 stars with 10 km resolution requires a free energy equivalent to the observed dark energy density. Finer encodings would require much higher energies inconsistent with observations. Thus dark energy may represent the cost of encoding classical information rather than a property of empty space.
Primordial Black Holes and r-Process NucleosynthesisSérgio Sacani
We show that some or all of the inventory of r-process nucleosynthesis can be produced in
interactions of primordial black holes (PBHs) with neutron stars (NSs) if PBHs with masses
10−14 M < MPBH < 10−8 M make up a few percent or more of the dark matter. A PBH captured
by a neutron star (NS) sinks to the center of the NS and consumes it from the inside. When this
occurs in a rotating millisecond-period NS, the resulting spin-up ejects ∼ 0.1 − 0.5 M of relatively
cold neutron-rich material. This ejection process and the accompanying decompression and decay
of nuclear matter can produce electromagnetic transients, such as a kilonova-type afterglow and
fast radio bursts. These transients are not accompanied by significant gravitational radiation or
neutrinos, allowing such events to be differentiated from compact object mergers occurring within
the distance sensitivity limits of gravitational wave observatories. The PBH-NS destruction scenario
is consistent with pulsar and NS statistics, the dark matter content and spatial distributions in the
Galaxy and Ultra Faint Dwarfs (UFD), as well as with the r-process content and evolution histories
in these sites. Ejected matter is heated by beta decay, which leads to emission of positrons in an
amount consistent with the observed 511-keV line from the Galactic Center.
Black hole entropy leads to the non-local grid dimensions theory Eran Sinbar
Based on Prof. Bekenstein and Prof. Hawking, the black hole maximal entropy , the maximum amount of information that a black hole can absorb, beyond its event horizon is proportional to the area of its event horizon divided by quantized area units, in the scale of Planck area (the square of Planck length).[1]
This quantization in entropy and information in the quantized units of Planck area leads us to the assumption that space is not “smooth” but rather divided into quantized units (“space cells”). Although the Bekenstein-Hawking entropy equation describes a specific case regarding the quantization of the 2D event horizon, this idea can be generalized to the standard 3 dimension (3D) flat space, outside and far away from the black hole’s event horizon. In this general case we assume that these quantized units of space are 3D quantized space “cells” in the scale of Planck length in each of its 3 dimensions.
If this is truly the case and the universe fabric of space is quantized to local 3D space cells in the magnitude size of Planck length scale in each dimension, than we assume that there must be extra non-local space dimensions situated in the non-local bordering’s of these 3D space cells since there must be something dividing space into these quantized space cells.
Our assumption is that these bordering’s are extra non local dimensions which we named as the “GRID” (or grid) extra dimensions, since they look like a non-local 3D grid bordering of the local 3D space cells. These non-local grid dimensions are responsible for all unexplained non-local phenomena’s like the well-known non-local entanglement or in the phrase of Albert Einstein “spooky action at a distance” [2].So by proving that space-time is quantized we prove the existence of the non-local grid dimension that divides space-time to these quantized 3D Planck scale cells.
- The document discusses going beyond the standard model of cosmology which assumes a flat Lambda Cold Dark Matter (LCDM) universe with a power-law primordial spectrum.
- It suggests that the universe could be more complicated and that extensions to the standard model need to be properly investigated using advanced statistical methods and high quality observational data.
- Examples of possible extensions discussed include allowing the primordial power spectrum to take on different forms beyond a simple power law, or exploring the possibility that dark energy is not a cosmological constant.
This document analyzes extensions of the Standard Model that naturally accommodate tiny neutrino masses through the exchange of heavy particles. It discusses how neutrino masses are generated at tree-level by seesaw mechanisms involving fermionic singlets/triplets or scalar triplets. Dimension-six operators are also explored, as they may allow observable low-energy effects even with suppressed dimension-five operators. Phenomenological consequences are then analyzed, with a focus on charged lepton flavor violating processes and constraints from rare decays.
A revised upper_limit_to_energy_extraction_from_a_kerr_black_holeSérgio Sacani
Uma nova simulação computacional feita pela NASA mostra que as partículas da matéria escura colidindo na extrema gravidade de um buraco negro pode produzir uma luz de raios-gamma forte e potencialmente observável. Detectando essa emissão forneceria aos astrônomos com uma nova ferramenta para entender tanto os buracos negros como a natureza da matéria escura, uma elusiva substância responsável pela maior parte da massa do universo que nem reflete, absorve ou emite luz.
Using observations from the Very Large Telescope, astronomers have discovered a dense gas cloud approximately three times the mass of Earth that is falling towards the supermassive black hole at the center of the Milky Way. The cloud is on a highly eccentric orbit that will bring it as close as 3,100 times the event horizon of the black hole in 2013. Over the past three years, the cloud has begun to disrupt due to tidal shearing from the black hole's gravitational forces, and its dynamic evolution over the next few years will provide insights into the black hole's accretion processes.
- The document discusses a braneworld model where a 3-brane moves in a 5-dimensional anti-de Sitter bulk. The brane behaves effectively as a tachyon field with an inverse quartic potential.
- When the backreaction of the radion field (related to fluctuations of the brane position) is included, the tachyon Lagrangian is modified by its interaction with the radion. This results in an effective equation of state at large scales that describes "warm dark matter".
- The model extends the second Randall-Sundrum braneworld model to include nonlinear effects from the radion field, which distorts the anti-de Sitter geometry.
The document discusses using gravitational wave waveform models to infer astrophysical properties from observations of gravitational wave events. It describes how waveform models encode information about binary black hole parameters like mass and spin, and how Bayesian inference can be used to estimate these parameters from the detected gravitational wave signal. It also addresses assessing confidence in detections and evaluating potential modeling systematics by comparing waveform models to numerical relativity simulations.
This document summarizes a study on using 21cm forest probes to explore axion dark matter scenarios where Peccei-Quinn symmetry breaks after inflation. The enhanced matter power spectrum from axion-generated isocurvature fluctuations would increase the number of 21cm absorption lines, probing axion masses from 10^-18 eV to 10^-12 eV. The optimal range to see effects is for oscillation scales around 2x10^4 Mpc^-1. However, detecting the 21cm forest requires bright background radio sources at high redshifts, which remain uncertain.
As recent and future galaxy surveys map the large-scale structure of the universe with unprecedented pace and precision, it is worthwhile to consider innovative data analysis methods beyond traditional Gaussian 2-point statistics to extract more cosmological information from those datasets. Such efforts are often plagued by substantially increased complexity of the analysis. Hoping to improve this, I will present simple, nearly optimal methods to measure 3-point statistics as easily as 2-point statistics, by cross-correlating the mass density with specific quadratic fields [arXiv:1411.6595]. Inspired by these results, I will argue that BAO reconstructions already combine 2-point statistics with certain 3- and 4-point functions automatically [arXiv:1508.06972]. I will present several new Eulerian and Lagrangian reconstruction algorithms and discuss their performance in simulations.
Precision determination of the small-x gluon from charm production at LHCbjuanrojochacon
This document discusses using LHCb data on charm production to constrain the small-x gluon and improve predictions for neutrino fluxes. LHCb data at 7 TeV, 5 TeV and 13 TeV provides stringent constraints on the small-x gluon beyond HERA. This improved gluon allows more accurate predictions for signals and backgrounds at neutrino telescopes. At a 100 TeV collider, inclusive cross sections depend directly on small-x PDFs, but using LHCb data leads to stabilized predictions with reduced uncertainties.
This document summarizes a presentation about reconstructing inflationary models in modified f(R) gravity. It discusses the current status of inflation based on Planck data, reviews how inflation works in f(R) gravity, and describes two approaches - the direct approach of comparing models to data and the inverse approach of smoothly reconstructing models from observational quantities like the scalar spectrum index. A key model discussed is the simple R + R^2 model that can match current measurements of the spectral index and tensor-to-scalar ratio.
The characterization of_the_gamma_ray_signal_from_the_central_milk_way_a_comp...Sérgio Sacani
This document analyzes the gamma-ray signal from the central Milky Way that is consistent with emission from annihilating dark matter particles. The authors re-examine Fermi data using cuts on an event parameter to improve gamma-ray maps and more easily separate components. They find the GeV excess is robust and well-fit by a 36-51 GeV dark matter particle annihilating to bottom quarks with a cross section of 1-3×10−26 cm3/s. The signal extends over 10 degrees from the Galactic Center and is spherically symmetric, disfavoring explanations from millisecond pulsars or gas interactions.
Forming intracluster gas in a galaxy protocluster at a redshift of 2.16Sérgio Sacani
Galaxy clusters are the most massive gravitationally bound structures in the Universe, comprising thousands of galaxies and
pervaded by a diffuse, hot “intracluster medium” (ICM) that dominates the baryonic content of these systems. The formation
and evolution of the ICM across cosmic time1
is thought to be driven by the continuous accretion of matter from the large-scale
filamentary surroundings and dramatic merger events with other clusters or groups. Until now, however, direct observations of
the intracluster gas have been limited only to mature clusters in the latter three-quarters of the history of the Universe, and we
have been lacking a direct view of the hot, thermalized cluster atmosphere at the epoch when the first massive clusters formed.
Here we report the detection (about 6σ) of the thermal Sunyaev-Zeldovich (SZ) effect2
in the direction of a protocluster. In fact,
the SZ signal reveals the ICM thermal energy in a way that is insensitive to cosmological dimming, making it ideal for tracing
the thermal history of cosmic structures3
. This result indicates the presence of a nascent ICM within the Spiderweb protocluster
at redshift z = 2.156, around 10 billion years ago. The amplitude and morphology of the detected signal show that the SZ
effect from the protocluster is lower than expected from dynamical considerations and comparable with that of lower-redshift
group-scale systems, consistent with expectations for a dynamically active progenitor of a local galaxy cluster.
This document summarizes a lecture on using gravitational wave waveform models to test general relativity and probe the nature of compact objects through gravitational wave observations. It discusses how waveform models can be used to bound post-Newtonian coefficients, constrain phenomenological merger-ringdown parameters, and probe the quasi-normal modes of black hole ringdowns. Measuring multiple modes could verify the no-hair theorem and black hole uniqueness properties. Future observations from LIGO and Virgo at design sensitivity may allow high-precision black hole spectroscopy and tests of general relativity in the strong, dynamical gravity regime.
1. The document discusses potential low frequency gravitational wave sources that could be detected by LISA, including galactic white dwarf binaries, massive black hole binaries, and extreme mass ratio inspirals.
2. LISA could detect thousands of massive black hole binaries and provide precise measurements of their parameters like mass and spin, enabling tests of general relativity and learning about black hole formation mechanisms.
3. Extreme mass ratio inspirals where a compact object spirals into a massive black hole could occur at a rate of 10-7 per year in our galaxy, allowing precision cosmology and tests of the no-hair theorem.
This document provides an overview of dimuon analyses at the LHC and discusses big data challenges. It outlines the Standard Model and motivations for new physics searches. The CMS detector is described, focusing on muon reconstruction challenges. Data selection and efficiency measurements are discussed. The analysis philosophy of searching for a narrow resonance over the Drell-Yan continuum is presented.
1) Massive black hole binaries form during galaxy mergers and evolve through dynamical friction and 3-body interactions with stars until reaching separations of ~0.01 pc where gravitational wave emission takes over.
2) Gas dynamics may also drive black hole binaries to smaller separations for coalescence.
3) Black hole binary coalescence timescales are typically long, on the order of billions of years, which has implications for gravitational wave detection and triple black hole interactions.
A. De Simone: The Quest for Dark Matter: Update and NewsSEENET-MTP
The document summarizes the status of dark matter searches from multiple experiments and detection strategies. It discusses evidence that dark matter exists from cosmological measurements and observations of galaxy rotations. It also outlines various dark matter candidate particles and the search strategies used, including direct detection experiments that have seen some positive hints of an annual modulation signal including DAMA/Libra and CoGeNT experiments, but are in tension with null results from Xenon, CDMS, and Edelweiss experiments. Collider searches for dark matter are also discussed.
The document discusses gravitational waves and binary systems. It provides context on the history of gravitational wave detection, from Einstein's early work developing the theory of gravitational waves to Joseph Weber's pioneering efforts to detect them in the 1960s. It also summarizes the development of laser interferometer gravitational wave detectors by researchers in the US, Germany, Italy, and the UK beginning in the 1970s and 1980s. Key detections by LIGO and Virgo are noted, including GW150914 in 2015. Theoretical work on modeling gravitational waveforms from coalescing compact binaries is summarized, from early perturbative approaches to more recent analytical methods like the effective one-body formalism.
This document proposes that dark energy may be an artifact of the free energy required to encode classical information about quantum systems into the environment. It applies the framework of quantum Darwinism to model how the positions of stars are encoded in the ambient photon field. Assuming Landauer's principle, encoding the positions of 10^25 stars with 10 km resolution requires a free energy equivalent to the observed dark energy density. Finer encodings would require much higher energies inconsistent with observations. Thus dark energy may represent the cost of encoding classical information rather than a property of empty space.
Primordial Black Holes and r-Process NucleosynthesisSérgio Sacani
We show that some or all of the inventory of r-process nucleosynthesis can be produced in
interactions of primordial black holes (PBHs) with neutron stars (NSs) if PBHs with masses
10−14 M < MPBH < 10−8 M make up a few percent or more of the dark matter. A PBH captured
by a neutron star (NS) sinks to the center of the NS and consumes it from the inside. When this
occurs in a rotating millisecond-period NS, the resulting spin-up ejects ∼ 0.1 − 0.5 M of relatively
cold neutron-rich material. This ejection process and the accompanying decompression and decay
of nuclear matter can produce electromagnetic transients, such as a kilonova-type afterglow and
fast radio bursts. These transients are not accompanied by significant gravitational radiation or
neutrinos, allowing such events to be differentiated from compact object mergers occurring within
the distance sensitivity limits of gravitational wave observatories. The PBH-NS destruction scenario
is consistent with pulsar and NS statistics, the dark matter content and spatial distributions in the
Galaxy and Ultra Faint Dwarfs (UFD), as well as with the r-process content and evolution histories
in these sites. Ejected matter is heated by beta decay, which leads to emission of positrons in an
amount consistent with the observed 511-keV line from the Galactic Center.
Black hole entropy leads to the non-local grid dimensions theory Eran Sinbar
Based on Prof. Bekenstein and Prof. Hawking, the black hole maximal entropy , the maximum amount of information that a black hole can absorb, beyond its event horizon is proportional to the area of its event horizon divided by quantized area units, in the scale of Planck area (the square of Planck length).[1]
This quantization in entropy and information in the quantized units of Planck area leads us to the assumption that space is not “smooth” but rather divided into quantized units (“space cells”). Although the Bekenstein-Hawking entropy equation describes a specific case regarding the quantization of the 2D event horizon, this idea can be generalized to the standard 3 dimension (3D) flat space, outside and far away from the black hole’s event horizon. In this general case we assume that these quantized units of space are 3D quantized space “cells” in the scale of Planck length in each of its 3 dimensions.
If this is truly the case and the universe fabric of space is quantized to local 3D space cells in the magnitude size of Planck length scale in each dimension, than we assume that there must be extra non-local space dimensions situated in the non-local bordering’s of these 3D space cells since there must be something dividing space into these quantized space cells.
Our assumption is that these bordering’s are extra non local dimensions which we named as the “GRID” (or grid) extra dimensions, since they look like a non-local 3D grid bordering of the local 3D space cells. These non-local grid dimensions are responsible for all unexplained non-local phenomena’s like the well-known non-local entanglement or in the phrase of Albert Einstein “spooky action at a distance” [2].So by proving that space-time is quantized we prove the existence of the non-local grid dimension that divides space-time to these quantized 3D Planck scale cells.
- The document discusses going beyond the standard model of cosmology which assumes a flat Lambda Cold Dark Matter (LCDM) universe with a power-law primordial spectrum.
- It suggests that the universe could be more complicated and that extensions to the standard model need to be properly investigated using advanced statistical methods and high quality observational data.
- Examples of possible extensions discussed include allowing the primordial power spectrum to take on different forms beyond a simple power law, or exploring the possibility that dark energy is not a cosmological constant.
This document analyzes extensions of the Standard Model that naturally accommodate tiny neutrino masses through the exchange of heavy particles. It discusses how neutrino masses are generated at tree-level by seesaw mechanisms involving fermionic singlets/triplets or scalar triplets. Dimension-six operators are also explored, as they may allow observable low-energy effects even with suppressed dimension-five operators. Phenomenological consequences are then analyzed, with a focus on charged lepton flavor violating processes and constraints from rare decays.
A revised upper_limit_to_energy_extraction_from_a_kerr_black_holeSérgio Sacani
Uma nova simulação computacional feita pela NASA mostra que as partículas da matéria escura colidindo na extrema gravidade de um buraco negro pode produzir uma luz de raios-gamma forte e potencialmente observável. Detectando essa emissão forneceria aos astrônomos com uma nova ferramenta para entender tanto os buracos negros como a natureza da matéria escura, uma elusiva substância responsável pela maior parte da massa do universo que nem reflete, absorve ou emite luz.
Using observations from the Very Large Telescope, astronomers have discovered a dense gas cloud approximately three times the mass of Earth that is falling towards the supermassive black hole at the center of the Milky Way. The cloud is on a highly eccentric orbit that will bring it as close as 3,100 times the event horizon of the black hole in 2013. Over the past three years, the cloud has begun to disrupt due to tidal shearing from the black hole's gravitational forces, and its dynamic evolution over the next few years will provide insights into the black hole's accretion processes.
- The document discusses a braneworld model where a 3-brane moves in a 5-dimensional anti-de Sitter bulk. The brane behaves effectively as a tachyon field with an inverse quartic potential.
- When the backreaction of the radion field (related to fluctuations of the brane position) is included, the tachyon Lagrangian is modified by its interaction with the radion. This results in an effective equation of state at large scales that describes "warm dark matter".
- The model extends the second Randall-Sundrum braneworld model to include nonlinear effects from the radion field, which distorts the anti-de Sitter geometry.
The document discusses using gravitational wave waveform models to infer astrophysical properties from observations of gravitational wave events. It describes how waveform models encode information about binary black hole parameters like mass and spin, and how Bayesian inference can be used to estimate these parameters from the detected gravitational wave signal. It also addresses assessing confidence in detections and evaluating potential modeling systematics by comparing waveform models to numerical relativity simulations.
This document summarizes a study on using 21cm forest probes to explore axion dark matter scenarios where Peccei-Quinn symmetry breaks after inflation. The enhanced matter power spectrum from axion-generated isocurvature fluctuations would increase the number of 21cm absorption lines, probing axion masses from 10^-18 eV to 10^-12 eV. The optimal range to see effects is for oscillation scales around 2x10^4 Mpc^-1. However, detecting the 21cm forest requires bright background radio sources at high redshifts, which remain uncertain.
As recent and future galaxy surveys map the large-scale structure of the universe with unprecedented pace and precision, it is worthwhile to consider innovative data analysis methods beyond traditional Gaussian 2-point statistics to extract more cosmological information from those datasets. Such efforts are often plagued by substantially increased complexity of the analysis. Hoping to improve this, I will present simple, nearly optimal methods to measure 3-point statistics as easily as 2-point statistics, by cross-correlating the mass density with specific quadratic fields [arXiv:1411.6595]. Inspired by these results, I will argue that BAO reconstructions already combine 2-point statistics with certain 3- and 4-point functions automatically [arXiv:1508.06972]. I will present several new Eulerian and Lagrangian reconstruction algorithms and discuss their performance in simulations.
Precision determination of the small-x gluon from charm production at LHCbjuanrojochacon
This document discusses using LHCb data on charm production to constrain the small-x gluon and improve predictions for neutrino fluxes. LHCb data at 7 TeV, 5 TeV and 13 TeV provides stringent constraints on the small-x gluon beyond HERA. This improved gluon allows more accurate predictions for signals and backgrounds at neutrino telescopes. At a 100 TeV collider, inclusive cross sections depend directly on small-x PDFs, but using LHCb data leads to stabilized predictions with reduced uncertainties.
This document summarizes a presentation about reconstructing inflationary models in modified f(R) gravity. It discusses the current status of inflation based on Planck data, reviews how inflation works in f(R) gravity, and describes two approaches - the direct approach of comparing models to data and the inverse approach of smoothly reconstructing models from observational quantities like the scalar spectrum index. A key model discussed is the simple R + R^2 model that can match current measurements of the spectral index and tensor-to-scalar ratio.
The characterization of_the_gamma_ray_signal_from_the_central_milk_way_a_comp...Sérgio Sacani
This document analyzes the gamma-ray signal from the central Milky Way that is consistent with emission from annihilating dark matter particles. The authors re-examine Fermi data using cuts on an event parameter to improve gamma-ray maps and more easily separate components. They find the GeV excess is robust and well-fit by a 36-51 GeV dark matter particle annihilating to bottom quarks with a cross section of 1-3×10−26 cm3/s. The signal extends over 10 degrees from the Galactic Center and is spherically symmetric, disfavoring explanations from millisecond pulsars or gas interactions.
Forming intracluster gas in a galaxy protocluster at a redshift of 2.16Sérgio Sacani
Galaxy clusters are the most massive gravitationally bound structures in the Universe, comprising thousands of galaxies and
pervaded by a diffuse, hot “intracluster medium” (ICM) that dominates the baryonic content of these systems. The formation
and evolution of the ICM across cosmic time1
is thought to be driven by the continuous accretion of matter from the large-scale
filamentary surroundings and dramatic merger events with other clusters or groups. Until now, however, direct observations of
the intracluster gas have been limited only to mature clusters in the latter three-quarters of the history of the Universe, and we
have been lacking a direct view of the hot, thermalized cluster atmosphere at the epoch when the first massive clusters formed.
Here we report the detection (about 6σ) of the thermal Sunyaev-Zeldovich (SZ) effect2
in the direction of a protocluster. In fact,
the SZ signal reveals the ICM thermal energy in a way that is insensitive to cosmological dimming, making it ideal for tracing
the thermal history of cosmic structures3
. This result indicates the presence of a nascent ICM within the Spiderweb protocluster
at redshift z = 2.156, around 10 billion years ago. The amplitude and morphology of the detected signal show that the SZ
effect from the protocluster is lower than expected from dynamical considerations and comparable with that of lower-redshift
group-scale systems, consistent with expectations for a dynamically active progenitor of a local galaxy cluster.
Artigo que descreve o trabalho feito com o Chandra nos aglomerados de galáxias de Perseus e Virgo sobre a descoberta de uma turbulência cósmica que impede a formação de novas estrelas.
A massive protocluster of galaxies at a redshift of z<5.3Sérgio Sacani
This document describes the discovery of a massive protocluster of galaxies located approximately 1 billion years after the Big Bang (redshift of z=5.3). The protocluster contains overdense regions of massive galaxies extending over 13 megaparsecs. It contains an extremely luminous starburst galaxy with large molecular gas reserves and a luminous quasar. Together, these objects place a minimum total mass of over 4×1011 solar masses in this early cluster, consistent with cosmological simulations of the earliest galaxy clusters. This discovery provides evidence for the hierarchical formation of massive structures in the early universe.
Magnetic support of_the_optical_emission_line_filaments_in_ngc_1275Sérgio Sacani
1) New Hubble Space Telescope observations of the galaxy NGC 1275 reveal thin thread-like structures within its emission line filaments that extend over 6 kpc but are only 70 pc wide.
2) It is concluded that magnetic fields within the threads, in pressure balance with the surrounding hot gas, are stabilizing the filaments and allowing a large mass of cold gas to accumulate without forming stars.
3) The inferred magnetic field strengths of 10-100 microgauss are sufficient to support the filaments against gravity and tidal forces, and would make the filaments magnetically dominated structures similar to molecular clouds in the Milky Way.
Possible interaction between baryons and dark-matter particles revealed by th...Sérgio Sacani
This document discusses how the interaction between baryons (normal matter) and dark matter particles could explain an excess absorption signal detected in the 21-centimeter spectrum from the early universe. The interaction would provide excess cooling of the cosmic gas through scattering with colder dark matter particles. Calculations show this interaction could produce absorption signals 1 order of magnitude larger than expected and constrain the dark matter particle mass to less than a few proton masses. Observing spatial fluctuations in the 21-centimeter signal could probe dark matter properties and be used as a new dark matter detector.
Dissecting x ray_emitting_gas_around_the_center_of_our_galaxySérgio Sacani
1) The Chandra X-ray Observatory was used to observe the supermassive black hole at the center of the Milky Way, Sgr A*, for a total of 3 megaseconds.
2) The observations revealed extended X-ray emission around Sgr A* that aligns spatially with a surrounding disk of massive stars.
3) Spectral analysis ruled out low-mass stars as the origin of the X-ray emission and instead found evidence that the emission is from a radiatively inefficient accretion flow onto the black hole, with an outflow present.
Detection of an_unindentified_emission_line_in_the_stacked_x_ray_spectrum_of_...Sérgio Sacani
1. Researchers detected a previously unknown emission line in the stacked X-ray spectrum of 73 galaxy clusters observed by XMM-Newton. 2. The line was detected at an energy of 3.55-3.57 keV and was seen independently in subsamples of clusters. 3. The line was also detected in Chandra observations of the Perseus cluster but not in observations of the Virgo cluster. 4. The nature of this line is unclear - it could be a thermal line from an undetected element, or potentially the decay line of a hypothesized dark matter particle called a sterile neutrino. Further observations are needed to determine the origin of the line.
The first X-ray look at SMSS J114447.77-430859.3: the most luminous quasar in...Sérgio Sacani
SMSS J114447.77-430859.3 (z = 0.83) has been identified in the SkyMapper Southern Survey as the most luminous quasar in
the last ∼ 9 Gyr . In this paper, we report on the eROSITA/Spectrum–Roentgen–Gamma (SRG) observations of the source from
the eROSITA All Sky Survey, along with presenting results from recent monitoring performed using Swift, XMM-Newton, and
NuSTAR. The source shows a clear variability by factors of ∼10 and ∼2.7 overtime-scales of a year and of a few days,respectively.
When fit with an absorbed power law plus high-energy cutoff, the X-ray spectra reveal a = 2.2 ± 0.2 and Ecut = 23+26
−5 keV
. Assuming Comptonization, we estimate a coronal optical depth and electron temperature of τ = 2.5 − 5.3 (5.2 − 8) and
kT = 8 − 18 (7.5 − 14) keV , respectively, for a slab (spherical) geometry. The broadband SED is successfully modelled by
assuming either a standard accretion disc illuminated by a central X-ray source, or a thin disc with a slim disc emissivity profile.
The former model results in a black hole mass estimate of the order of 1010 M , slightly higher than prior optical estimates;
meanwhile, the latter model suggests a lower mass. Both models suggest sub-Eddington accretion when assuming a spinning
black hole, and a compact (∼ 10 rg ) X-ray corona. The measured intrinsic column density and the Eddington ratio strongly
suggest the presence of an outflow driven by radiation pressure. This is also supported by variation of absorption by an order of
magnitude over the period of ∼ 900 d .
Exploring Proxies for the Supermassive Black Hole Mass Function: Implications...Sérgio Sacani
Supermassive black holes (SMBHs) reside at the center of every massive galaxy in the local universe with masses
that closely correlate with observations of their host galaxy, implying a connected evolutionary history. The
population of binary SMBHs, which form following galaxy mergers, is expected to produce a gravitational-wave
background (GWB) detectable by pulsar timing arrays (PTAs). PTAs are starting to see hints of what may be a
GWB, and the amplitude of the emerging signal is toward the higher end of model predictions. Simulated
populations of binary SMBHs can be constructed from observations of galaxies and are used to make predictions
about the nature of the GWB. The greatest source of uncertainty in these observation-based models comes from the
inference of the SMBH mass function, which is derived from observed host galaxy properties. In this paper, I
undertake a new approach for inferring the SMBH mass function, starting from a velocity dispersion function
rather than a galaxy stellar mass function. I argue that this method allows for a more direct inference by relying on
a larger suite of individual galaxy observations as well as relying on a more “fundamental” SMBH mass relation. I
find that the resulting binary SMBH population contains more massive systems at higher redshifts than previous
models. Additionally, I explore the implications for the detection of individually resolvable sources in PTA data.
The current ability to test theories of gravity with black hole shadowsSérgio Sacani
Our Galactic Centre, Sagittarius A*, is believed to harbour a
supermassive black hole, as suggested by observations tracking
individual orbiting stars1,2
. Upcoming submillimetre verylong
baseline interferometry images of Sagittarius A* carried
out by the Event Horizon Telescope collaboration (EHTC)3,4
are expected to provide critical evidence for the existence of
this supermassive black hole5,6. We assess our present ability
to use EHTC images to determine whether they correspond
to a Kerr black hole as predicted by Einstein’s theory
of general relativity or to a black hole in alternative theories
of gravity. To this end, we perform general-relativistic magnetohydrodynamical
simulations and use general-relativistic
radiative-transfer calculations to generate synthetic shadow
images of a magnetized accretion flow onto a Kerr black hole.
In addition, we perform these simulations and calculations for
a dilaton black hole, which we take as a representative solution
of an alternative theory of gravity. Adopting the very-long
baseline interferometry configuration from the 2017 EHTC
campaign, we find that it could be extremely difficult to distinguish
between black holes from different theories of gravity,
thus highlighting that great caution is needed when interpreting
black hole images as tests of general relativity.
This document describes an ongoing study of young quasars to understand active galactic nucleus (AGN) feedback. The study uses optical data from the Large Binocular Telescope and its Large Binocular Camera to observe 33 obscured, radio-loud quasar targets selected from infrared and radio surveys. The targets span redshifts from 1.4 to 3 and may show evidence of radiative or quasar-mode feedback through interactions between newly formed radio jets and the interstellar medium. Understanding AGN feedback can provide insights into the evolution of galaxies and the universe.
2014 NJP - Oscillatory solitons and time-resolved phase locking of two polari...Guilherme Tosi
This document summarizes time-resolved measurements of two polariton condensates formed in a semiconductor microcavity under nonresonant excitation. The measurements directly observe oscillatory behavior as dark or bright soliton-like waves form between the excitation spots. They also observe phase locking of the two initially independent condensates over time. These phenomena provide insights into the underlying dynamics of polariton-polariton interactions and propagation of polariton condensates.
This document reports the detection of a low-mass dark satellite galaxy in a gravitational lens system. Using pixelated lens modeling of adaptive optics images, the researchers detected a positive density correction indicating the presence of a mass substructure. They estimate the mass of the substructure to be 1.9 x 108 solar masses located 600 parsecs from the density peak. Combining this detection with a previous one, they constrain the logarithmic slope of the mass function for dark matter substructure in elliptical galaxies to be 1.1-0.4 with an average mass fraction of 3.3-1.8%. This is consistent with predictions from cold dark matter simulations.
The colision between_the_milky_way_and_andromedaSérgio Sacani
The document summarizes a simulation of the future collision between the Milky Way and Andromeda galaxies. It finds that given current observational constraints on their distance, velocity, and masses:
1) The Milky Way and Andromeda are likely to collide in a few billion years, within the lifetime of the Sun.
2) During the interaction, there is a chance the Sun could be pulled into an extended tidal tail between the galaxies.
3) Eventually, after the merger is complete, the Sun would most likely be scattered to the outer halo of the merged galaxy at a distance over 30 kpc.
Water vapour absorption_in_the_clear_atmosphere_of_a_neptune_sized_exoplanetSérgio Sacani
This document summarizes research on the transmission spectrum of the exoplanet HAT-P-11b, a Neptune-sized planet. Observations from the Hubble Space Telescope and Spitzer Space Telescope detected water vapor absorption in the planet's atmosphere at a wavelength of 1.4 micrometers. Analysis of the spectrum indicates the atmosphere is predominantly clear down to 1 mbar and has a hydrogen abundance similar to solar values. Atmospheric modeling suggests a metallicity around 190 times that of the Sun's, in agreement with core accretion planet formation theories. This makes HAT-P-11b the smallest exoplanet to date with a detected molecular signature in its atmosphere, providing new insights into the composition and formation of Neptune-sized
While most of the singularities of General Relativity are expected to be safely hidden behind event horizons by the cosmic censorship conjecture, we happen to live in the causal future of the classical big bang singularity, whose resolution constitutes the active field of early universe cosmology...
Discovery of a radiation component from the Vela pulsar reaching 20 teraelect...Sérgio Sacani
Gamma-ray observations have established energetic isolated pulsars as
outstanding particle accelerators and antimatter factories. However, many
questions are still open regarding the acceleration and radiation processes
involved, as well as the locations where they occur. The radiation spectra of
all gamma-ray pulsars observed to date show strong cutofs or a break above
energies of a few gigaelectronvolts. Using the High Energy Stereoscopic
System’s Cherenkov telescopes, we discovered a radiation component from
the Vela pulsar which emerges beyond this generic cutof and extends up to
energies of at least 20 teraelectronvolts. This is an order of magnitude larger
than in the case of the Crab pulsar, the only other pulsar detected in the
teraelectronvolt energy range. Our results challenge the state-of-the-art
models for the high-energy emission of pulsars. Furthermore, they pave
the way for investigating other pulsars through their multiteraelectronvolt
emission, thereby imposing additional constraints on the acceleration and
emission processes in their extreme energy limit.
Similar to The local nanohertz gravitational-wave landscape from supermassive black hole binaries (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.
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.
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.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
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.
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.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
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)”
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html