1. The document analyzes data from the Cosmic Origins Spectrograph aboard the Hubble Space Telescope to study the incidence of absorption at the interface between galaxies and the intergalactic medium (IGM).
2. Measurements of parameters like equivalent width and Doppler width from absorption line profiles are used to determine properties of the IGM like temperature and metallicity.
3. The analysis finds an average IGM temperature of 5 x 10^4 K and metallicity around 1/10 of solar, and suggests the IGM surrounding galaxies may have a patchy distribution based on a lack of correlation between equivalent width and impact parameter.
A rare case of FR I interaction with a hot X-ray bridge in the A2384 galaxy c...Sérgio Sacani
Clusters of varying mass ratios can merge and the process significantly disturbs
the cluster environments and alters their global properties. Active radio galaxies are
another phenomenon that can also affect cluster environments. Radio jets can interact
with the intra-cluster medium (ICM) and locally affect its properties. Abell 2384
(hereafter A2384) is a unique system that has a dense, hot X-ray filament or bridge
connecting the two unequal mass clusters A2384(N) and A2384(S). The analysis of its
morphology suggests that A2384 is a post-merger system where A2384(S) has already
interacted with the A2384(N), and as a result hot gas has been stripped over a ∼ 1
Mpc region between the two bodies. We have obtained its 325 MHz GMRT data,
and we detected a peculiar FR I type radio galaxy which is a part of the A2384(S).
One of its radio lobes interacts with the hot X-ray bridge and pushes the hot gas in
the opposite direction. This results in displacement in the bridge close to A2384(S).
Based on Chandra and XMM-Newton X-ray observations, we notice a temperature and
entropy enhancement at the radio lobe-X-ray plasma interaction site, which further
suggests that the radio lobe is changing thermal plasma properties. We have also
studied the radio properties of the FR I radio galaxy, and found that the size and
radio luminosity of the interacting north lobe of the FR I galaxy are lower than those
of the accompanying south lobe.
This document describes observations of the Seyfert 1 galaxy Mrk 509 using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). The observations detected absorption features in the ultraviolet spectrum, which are attributed to outflowing gas from the active galactic nucleus as well as gas in the galaxy's interstellar medium and halo. The COS observations provide higher signal-to-noise and resolution than previous observations, detecting additional complexity in the absorption features. Variability in some features constrains the distances of absorbing gas components to be less than 250 pc and 1.5 kpc from the active nucleus. The absorption lines only partially cover the emission from the active nucleus, possibly due to
Spitzer Observations of the Predicted Eddington Flare from Blazar OJ 287Sérgio Sacani
Binary black hole (BH) central engine description for the unique blazar OJ 287 predicted that the
next secondary BH impact-induced bremsstrahlung flare should peak on 2019 July 31. This prediction
was based on detailed general relativistic modeling of the secondary BH trajectory around the primary
BH and its accretion disk. The expected flare was termed the Eddington flare to commemorate the
centennial celebrations of now-famous solar eclipse observations to test general relativity by Sir Arthur
Corresponding author: Lankeswar Dey
lankeswar.dey@tifr.res.in
arXiv:2004.13392v1 [astro-ph.HE] 28 Apr 2020
2 Laine et al.
Eddington. We analyze the multi-epoch Spitzer observations of the expected flare between 2019 July
31 and 2019 September 6, as well as baseline observations during 2019 February–March. Observed
Spitzer flux density variations during the predicted outburst time display a strong similarity with
the observed optical pericenter flare from OJ 287 during 2007 September. The predicted flare appears
comparable to the 2007 flare after subtracting the expected higher base-level Spitzer flux densities at
3.55 and 4.49 µm compared to the optical R-band. Comparing the 2019 and 2007 outburst lightcurves
and the previously calculated predictions, we find that the Eddington flare arrived within 4 hours of
the predicted time. Our Spitzer observations are well consistent with the presence of a nano-Hertz
gravitational wave emitting spinning massive binary BH that inspirals along a general relativistic
eccentric orbit in OJ 287. These multi-epoch Spitzer observations provide a parametric constraint
on the celebrated BH no-hair theorem.
A giant galaxy in the young Universe with a massive ringSérgio Sacani
In the local (redshift z ≈ 0) Universe, collisional ring galaxies make up only ~0.01% of galaxies1 and are formed by head-on galactic collisions that trigger radially propagating density waves2–4. These striking systems provide key snapshots for dissecting galactic disks and are studied extensively in the local Universe5–9. However, not much is known about distant (z > 0.1) collisional rings10–14. Here we present a detailed study of a ring galaxy at a look-back time of 10.8 Gyr (z = 2.19). Compared with our Milky Way, this galaxy has a similar stellar mass, but has a stellar half-light radius that is 1.5–2.2 times larger and is forming stars 50 times faster. The extended, dif- fuse stellar light outside the star-forming ring, combined with a radial velocity on the ring and an intruder galaxy nearby, provides evidence for this galaxy hosting a collisional ring. If the ring is secularly evolved15,16, the implied large bar in a giant disk would be inconsistent with the current understand- ing of the earliest formation of barred spirals17–21. Contrary to previous predictions10–12, this work suggests that massive col- lisional rings were as rare 11 Gyr ago as they are today. Our discovery offers a unique pathway for studying density waves in young galaxies, as well as constraining the cosmic evolution of spiral disks and galaxy groups.
Haze heats Pluto’s atmosphere yet explains its cold temperatureSérgio Sacani
Pluto’s atmosphere is cold and hazy1–3. Recent observations1
have
shown it to be much colder than predicted theoretically4
, suggesting
an unknown cooling mechanism1
. Atmospheric gas molecules,
particularly water vapour, have been proposed as a coolant;
however, because Pluto’s thermal structure is expected to be in
radiative–conductive equilibrium4–9, the required water vapour
would need to be supersaturated by many orders of magnitude
under thermodynamic equilibrium conditions9
. Here we report
that atmospheric hazes, rather than gases, can explain Pluto’s
temperature profile. We find that haze particles have substantially
larger solar heating and thermal cooling rates than gas molecules,
dominating the atmospheric radiative balance from the ground to an
altitude of 700 kilometres, above which heat conduction maintains
an isothermal atmosphere. We conclude that Pluto’s atmosphere is
unique among Solar System planetary atmospheres, as its radiative
energy equilibrium is controlled primarily by haze particles instead
of gas molecules. We predict that Pluto is therefore several orders
of magnitude brighter at mid-infrared wavelengths than previously
thought—a brightness that could be detected by future telescopes.
This study analyzed transit observations of the Neptune-mass exoplanet GJ 436b taken with the Hubble Space Telescope. The transmission spectrum was found to be featureless, ruling out cloud-free hydrogen-dominated atmosphere models with high significance. The flat transmission spectrum is consistent with either an atmosphere containing high-altitude clouds located at a pressure of around 1 millibar, or a relatively hydrogen-poor atmosphere with 3% hydrogen and helium by mass. Bayesian atmospheric modeling showed that cloudy hydrogen-dominated or high-metallicity hydrogen-poor atmospheres provide the best fits to the data. Further observations are needed to distinguish between these scenarios.
Inference of homogeneous_clouds_in_an_exoplanet_atmosphereSérgio Sacani
1) New visible and infrared observations of the exoplanet Kepler-7b were analyzed to determine its atmospheric properties and detect the presence of clouds.
2) The observations found a westward shift in Kepler-7b's optical phase curve and placed upper limits on its thermal emission that remained undetected in Spitzer bandpasses.
3) The data suggests Kepler-7b has optically thick, high-altitude clouds located west of the substellar point, composed possibly of silicates. The clouds help explain Kepler-7b's unusually high geometric albedo and visible flux that cannot be attributed to thermal emission or molecular hydrogen scattering alone.
Successful search for ether drift in a modified michelson morley experiment u...Võ Hồng Quý
This modified Michelson-Morley experiment directly measured the travel times of light using GPS clocks placed along the arms, instead of indirectly measuring fringe shifts. It detected differences in travel times for light moving east-west, consistent with the Earth's rotational motion causing ether drift, but no differences north-south. This provides evidence for the existence of ether drift in a way not subject to the length contraction effects that obscured results of previous experiments. The GPS clocks precisely confirmed the light travel times predicted by ether theory for the changing speed of light due to the apparatus moving through the ether as the Earth rotates.
A rare case of FR I interaction with a hot X-ray bridge in the A2384 galaxy c...Sérgio Sacani
Clusters of varying mass ratios can merge and the process significantly disturbs
the cluster environments and alters their global properties. Active radio galaxies are
another phenomenon that can also affect cluster environments. Radio jets can interact
with the intra-cluster medium (ICM) and locally affect its properties. Abell 2384
(hereafter A2384) is a unique system that has a dense, hot X-ray filament or bridge
connecting the two unequal mass clusters A2384(N) and A2384(S). The analysis of its
morphology suggests that A2384 is a post-merger system where A2384(S) has already
interacted with the A2384(N), and as a result hot gas has been stripped over a ∼ 1
Mpc region between the two bodies. We have obtained its 325 MHz GMRT data,
and we detected a peculiar FR I type radio galaxy which is a part of the A2384(S).
One of its radio lobes interacts with the hot X-ray bridge and pushes the hot gas in
the opposite direction. This results in displacement in the bridge close to A2384(S).
Based on Chandra and XMM-Newton X-ray observations, we notice a temperature and
entropy enhancement at the radio lobe-X-ray plasma interaction site, which further
suggests that the radio lobe is changing thermal plasma properties. We have also
studied the radio properties of the FR I radio galaxy, and found that the size and
radio luminosity of the interacting north lobe of the FR I galaxy are lower than those
of the accompanying south lobe.
This document describes observations of the Seyfert 1 galaxy Mrk 509 using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). The observations detected absorption features in the ultraviolet spectrum, which are attributed to outflowing gas from the active galactic nucleus as well as gas in the galaxy's interstellar medium and halo. The COS observations provide higher signal-to-noise and resolution than previous observations, detecting additional complexity in the absorption features. Variability in some features constrains the distances of absorbing gas components to be less than 250 pc and 1.5 kpc from the active nucleus. The absorption lines only partially cover the emission from the active nucleus, possibly due to
Spitzer Observations of the Predicted Eddington Flare from Blazar OJ 287Sérgio Sacani
Binary black hole (BH) central engine description for the unique blazar OJ 287 predicted that the
next secondary BH impact-induced bremsstrahlung flare should peak on 2019 July 31. This prediction
was based on detailed general relativistic modeling of the secondary BH trajectory around the primary
BH and its accretion disk. The expected flare was termed the Eddington flare to commemorate the
centennial celebrations of now-famous solar eclipse observations to test general relativity by Sir Arthur
Corresponding author: Lankeswar Dey
lankeswar.dey@tifr.res.in
arXiv:2004.13392v1 [astro-ph.HE] 28 Apr 2020
2 Laine et al.
Eddington. We analyze the multi-epoch Spitzer observations of the expected flare between 2019 July
31 and 2019 September 6, as well as baseline observations during 2019 February–March. Observed
Spitzer flux density variations during the predicted outburst time display a strong similarity with
the observed optical pericenter flare from OJ 287 during 2007 September. The predicted flare appears
comparable to the 2007 flare after subtracting the expected higher base-level Spitzer flux densities at
3.55 and 4.49 µm compared to the optical R-band. Comparing the 2019 and 2007 outburst lightcurves
and the previously calculated predictions, we find that the Eddington flare arrived within 4 hours of
the predicted time. Our Spitzer observations are well consistent with the presence of a nano-Hertz
gravitational wave emitting spinning massive binary BH that inspirals along a general relativistic
eccentric orbit in OJ 287. These multi-epoch Spitzer observations provide a parametric constraint
on the celebrated BH no-hair theorem.
A giant galaxy in the young Universe with a massive ringSérgio Sacani
In the local (redshift z ≈ 0) Universe, collisional ring galaxies make up only ~0.01% of galaxies1 and are formed by head-on galactic collisions that trigger radially propagating density waves2–4. These striking systems provide key snapshots for dissecting galactic disks and are studied extensively in the local Universe5–9. However, not much is known about distant (z > 0.1) collisional rings10–14. Here we present a detailed study of a ring galaxy at a look-back time of 10.8 Gyr (z = 2.19). Compared with our Milky Way, this galaxy has a similar stellar mass, but has a stellar half-light radius that is 1.5–2.2 times larger and is forming stars 50 times faster. The extended, dif- fuse stellar light outside the star-forming ring, combined with a radial velocity on the ring and an intruder galaxy nearby, provides evidence for this galaxy hosting a collisional ring. If the ring is secularly evolved15,16, the implied large bar in a giant disk would be inconsistent with the current understand- ing of the earliest formation of barred spirals17–21. Contrary to previous predictions10–12, this work suggests that massive col- lisional rings were as rare 11 Gyr ago as they are today. Our discovery offers a unique pathway for studying density waves in young galaxies, as well as constraining the cosmic evolution of spiral disks and galaxy groups.
Haze heats Pluto’s atmosphere yet explains its cold temperatureSérgio Sacani
Pluto’s atmosphere is cold and hazy1–3. Recent observations1
have
shown it to be much colder than predicted theoretically4
, suggesting
an unknown cooling mechanism1
. Atmospheric gas molecules,
particularly water vapour, have been proposed as a coolant;
however, because Pluto’s thermal structure is expected to be in
radiative–conductive equilibrium4–9, the required water vapour
would need to be supersaturated by many orders of magnitude
under thermodynamic equilibrium conditions9
. Here we report
that atmospheric hazes, rather than gases, can explain Pluto’s
temperature profile. We find that haze particles have substantially
larger solar heating and thermal cooling rates than gas molecules,
dominating the atmospheric radiative balance from the ground to an
altitude of 700 kilometres, above which heat conduction maintains
an isothermal atmosphere. We conclude that Pluto’s atmosphere is
unique among Solar System planetary atmospheres, as its radiative
energy equilibrium is controlled primarily by haze particles instead
of gas molecules. We predict that Pluto is therefore several orders
of magnitude brighter at mid-infrared wavelengths than previously
thought—a brightness that could be detected by future telescopes.
This study analyzed transit observations of the Neptune-mass exoplanet GJ 436b taken with the Hubble Space Telescope. The transmission spectrum was found to be featureless, ruling out cloud-free hydrogen-dominated atmosphere models with high significance. The flat transmission spectrum is consistent with either an atmosphere containing high-altitude clouds located at a pressure of around 1 millibar, or a relatively hydrogen-poor atmosphere with 3% hydrogen and helium by mass. Bayesian atmospheric modeling showed that cloudy hydrogen-dominated or high-metallicity hydrogen-poor atmospheres provide the best fits to the data. Further observations are needed to distinguish between these scenarios.
Inference of homogeneous_clouds_in_an_exoplanet_atmosphereSérgio Sacani
1) New visible and infrared observations of the exoplanet Kepler-7b were analyzed to determine its atmospheric properties and detect the presence of clouds.
2) The observations found a westward shift in Kepler-7b's optical phase curve and placed upper limits on its thermal emission that remained undetected in Spitzer bandpasses.
3) The data suggests Kepler-7b has optically thick, high-altitude clouds located west of the substellar point, composed possibly of silicates. The clouds help explain Kepler-7b's unusually high geometric albedo and visible flux that cannot be attributed to thermal emission or molecular hydrogen scattering alone.
Successful search for ether drift in a modified michelson morley experiment u...Võ Hồng Quý
This modified Michelson-Morley experiment directly measured the travel times of light using GPS clocks placed along the arms, instead of indirectly measuring fringe shifts. It detected differences in travel times for light moving east-west, consistent with the Earth's rotational motion causing ether drift, but no differences north-south. This provides evidence for the existence of ether drift in a way not subject to the length contraction effects that obscured results of previous experiments. The GPS clocks precisely confirmed the light travel times predicted by ether theory for the changing speed of light due to the apparatus moving through the ether as the Earth rotates.
Herschel far infrared_spectroscopy_of_the_galactic_centerSérgio Sacani
The document summarizes observations from the Herschel Space Observatory of the Galactic Center region, focusing on a spectral scan toward Sagittarius A*. Key findings include:
1) Strong emission from atomic fine structure lines and rotationally excited lines of molecules like CO, H2O and HCO+ are detected.
2) The excitation of the CO ladder is consistent with either a hot isothermal gas component at 103.1 K and 104 cm-3, or a distribution of warmer gas at higher densities, with most CO at 300 K.
3) The detected molecular features suggest heating is from a combination of UV irradiation and shocks in the gas, rather than very enhanced X-ray or cosmic
Climatic consequences of regional nuclear conflicts27Nav
This study uses a climate model to simulate the climatic effects of a regional nuclear war between two countries using 100 Hiroshima-sized nuclear weapons on cities in the subtropics. The model finds that the smoke produced by urban fires would cause significant global cooling and reductions in precipitation lasting over a decade. The climate effects are more long-lasting than previous studies due to the smoke being lofted higher into the stratosphere where removal is slower. Reductions in surface sunlight, temperatures, and precipitation of up to 15 W/m^2, 1°C, and 9% respectively are found for several years globally following the conflict.
The document analyzes water vapor weighting functions using radiosonde data from locations between 58°N and 45°S latitude for July and August. It calculates water vapor absorption coefficients and weighting functions at different frequencies and heights. The results show that weighting functions bend more sharply above 2-3 km, indicating better vertical resolution for retrieving atmospheric parameters above this height. Among the frequencies analyzed, 23.834 GHz provided the best vertical resolution above 2-3 km based on the bending of its weighting function curves.
Use of atomic spectra for detection and determinationZainUIabedeen
Atomic spectra is the spectrum of electromagnetic radiation emitted or absorbed during electron transitions between energy levels within an atom. Each element has a characteristic atomic spectrum that can be used to identify it. There are two main types of atomic spectra: emission spectra produced when excited electrons return to lower energy states, and absorption spectra produced when electrons absorb radiation and move to higher energy states. Atomic spectra can be used for a variety of purposes including detecting elements and isotopes, determining the composition of materials like inorganic fertilizers and natural waters, and analyzing biological samples like blood, cerebrospinal fluid, and fingernails.
Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanetGOASA
1) The transmission spectrum of the exoplanet HAT-P-11b was observed using Hubble and Spitzer space telescopes.
2) Water vapor absorption was detected at 1.4 micrometers in the atmosphere, indicating a clear atmosphere down to 1 mbar pressure.
3) The detection of water vapor and relatively large atmospheric scale height places an upper limit on the abundance of heavy elements in the atmosphere of around 700 times the solar value, consistent with core accretion planet formation theories.
The document discusses a study of the relationship between coronal dimmings and coronal mass ejections (CMEs) associated with solar flares. An IDL program was written to analyze iron light curves from 55 flares exhibiting dimmings using SDO-EVE data. Correlations between flare parameters (duration, depth, slope) and CME parameters (velocity, mass) were computed, finding the slope of dimming correlated strongest with CME initial velocity, suggesting a relationship between dimming rate and CME launch speed.
The wonderful complexity_of_the_mira_ab_systemSérgio Sacani
The ALMA observations of the Mira AB binary system reveal an amazingly complex circumstellar environment shaped by multiple dynamical processes. In the blue wing of the CO emission line, opposing large arcs form a bubble structure around Mira A, possibly created by the wind from Mira B blowing into Mira A's expanding envelope. In the main line component, spiral arcs are seen around Mira A that appear relatively flat and oriented in the orbital plane. An accretion wake is also visible trailing Mira B. The companion is marginally resolved with a separation of 0.487 arcseconds from Mira A.
mass spectrometry for pesticides residue analysis- L2sherif Taha
This is the second lecture in series of lectures on mass spectrometry for pesticides residue analysis. This lecture (2) include: Electron ionization and Chemical ionization
The GRIPS instrument is a balloon-borne solar observatory designed to study particle acceleration during solar flares using imaging, spectroscopy, and polarimetry from 20 keV to 10 MeV. It successfully completed its first Antarctic long-duration balloon flight in January 2016, observing 21 C-class flares. GRIPS aims to address outstanding questions about the spatial separation of electron and ion emission sites, ion acceleration, electron anisotropy, and composition changes during flares. It utilizes new technologies like 3D position-sensitive germanium detectors and a single-grid modulator to improve on the resolution of previous instruments like RHESSI.
Meridional brightness temperatures were measured on the surface of Titan during the 2004–2014 portion of the
Cassini mission by the Composite Infrared Spectrometer. Temperatures mapped from pole to pole during five twoyear
periods show a marked seasonal dependence. The surface temperature near the south pole over this time
decreased by 2 K from 91.7±0.3 to 89.7±0.5 K while at the north pole the temperature increased by 1 K from
90.7±0.5 to 91.5±0.2 K. The latitude of maximum temperature moved from 19 S to 16 N, tracking the subsolar
latitude. As the latitude changed, the maximum temperature remained constant at 93.65±0.15 K. In 2010
our temperatures repeated the north–south symmetry seen by Voyager one Titan year earlier in 1980. Early in the
mission, temperatures at all latitudes had agreed with GCM predictions, but by 2014 temperatures in the north were
lower than modeled by 1 K. The temperature rise in the north may be delayed by cooling of sea surfaces and moist
ground brought on by seasonal methane precipitation and evaporation.
Titan’s aerosol and stratospheric ice opacities between 18 and 500 μm vertic...Sérgio Sacani
This document is an accepted manuscript for publication in Icarus that summarizes research analyzing data from the Cassini CIRS instrument to characterize Titan's stratospheric aerosols and ices between 18-500 μm. The research finds that aerosols are well-mixed from the surface to 300 km altitude, while nitrile ice clouds (likely HCN and HC3N) appear centered around 90 km. There is also evidence of an ice cloud layer at 60 km that may be C2H6 ice. Volume extinction coefficients derived from CIRS data are compared to those from DISR, finding particle size ratios consistent with sub-micron aerosols and ice particle effective radii of only a few microns.
The dispersion–brightness relation for fast radio bursts from a wide-field su...Sérgio Sacani
Despite considerable efforts over the past decade, only 34 fast radio
bursts—intense bursts of radio emission from beyond our Galaxy—
have been reported1,2
. Attempts to understand the population as a
whole have been hindered by the highly heterogeneous nature of the
searches, which have been conducted with telescopes of different
sensitivities, at a range of radio frequencies, and in environments
corrupted by different levels of radio-frequency interference
from human activity. Searches have been further complicated by
uncertain burst positions and brightnesses—a consequence of the
transient nature of the sources and the poor angular resolution of
the detecting instruments. The discovery of repeating bursts from
one source3
, and its subsequent localization4
to a dwarf galaxy at a
distance of 3.7 billion light years, confirmed that the population
of fast radio bursts is located at cosmological distances. However,
the nature of the emission remains elusive. Here we report a well
controlled, wide-field radio survey for these bursts. We found 20,
none of which repeated during follow-up observations between
185–1,097 hours after the initial detections. The sample includes
both the nearest and the most energetic bursts detected so far. The
survey demonstrates that there is a relationship between burst
dispersion and brightness and that the high-fluence bursts are
the nearby analogues of the more distant events found in highersensitivity,
narrower-field surveys5
.
This research summarizes measurements taken during the COPE-MED field campaign to better understand warm rain processes and entrainment effects on heavy precipitation. LWC probes were compared and generally agreed well, though the PVM overestimated LWC at higher concentrations and smaller diameters. A LWC survey with vertical statistics was conducted. Analysis of droplet spectra bimodality from low-precipitation cases found evidence of bimodality but secondary activation was unlikely the cause, with the bimodality mechanism remaining unclear. Future COPE analysis will utilize these LWC and bimodality findings to evaluate hypotheses regarding warm rain processes and entrainment impacts on heavy precipitation.
1) The document reports on phase-resolved emission spectroscopy observations of the exoplanet WASP-43b using the Hubble Space Telescope.
2) The observations tracked the planet over three full orbits and measured its thermal emission as a function of orbital phase, allowing the researchers to construct a map of the planet's atmospheric thermal structure.
3) The results found large day-night temperature variations at all measured altitudes, with temperature monotonically decreasing with increasing pressure. A low Bond albedo of 0.07-0.18 and offset of the hottest point from the substellar point were also derived.
Mass spectrometry involves ionizing molecule samples and then measuring their mass-to-charge ratios. The samples are bombarded with electrons to produce molecular ions, which then fragment into product ions. These ions are separated based on their mass-to-charge ratios and detected, producing a mass spectrum that shows the abundances of each ion. This spectrum provides structural information about the precursor molecule and can be used to identify unknown compounds. Mass spectrometry is widely applied across many scientific fields including pharmaceutical analysis, environmental testing, and forensics.
Direct detection of the enceladus water torus with herschelSérgio Sacani
The Herschel Space Observatory directly detected the water vapor torus around Saturn's moon Enceladus by observing absorption lines of water vapor against Saturn. Spectroscopic observations with Herschel's HIFI instrument detected water vapor lines at 557, 987, 1113, and 1670 GHz. Modeling of the spectra determined the water vapor has a column density of ~4 × 1013 cm-2 near the equatorial plane and a vertical scale height of ~50,000 km. The water torus appears rotationally cold at 16 K but is dynamically excited with non-Keplerian velocities of ~2 km/s, shaped largely by molecular collisions. Estimates of the influx of torus material into
Water vapor mapping on mars using omega mars expressAwad Albalwi
A systematic mapping of water vapor on Mars has been achieved using the imaging spectrometer OMEGA aboard the Mars Express
spacecraft, using the depth of the 2.6 mm (n1, n3) band of H2O. We report results obtained during two periods: (1) Ls ¼ 330–401
(January–June 2004), before and after the equinox, and (2) Ls ¼ 90–1251, which correspond to early northern summer
The document describes the challenges of measuring dayglow emissions and past attempts to do so. It summarizes:
1) Dayglow emission intensities are very low compared to the strong solar continuum background, making measurements difficult.
2) Past attempts used techniques like high-resolution scanning and subtracting the solar spectrum, but results were ambiguous and contributions from direct sunlight could not be separated.
3) Other techniques tested included using Fabry-Perot etalons and interference filters in series, as well as polarization properties to reduce the background, but definitive dayglow measurements were not obtained.
The document summarizes Spitzer observations of the supernova remnant IC 443. The MIPS images show the remnant's morphology in great detail, resembling a shell or loop. The dust temperature ranges from 18-30 K based on the 70/160um ratio. IRS spectroscopy confirms shock-excited atomic and molecular emission, with shock velocities of 60-90 km/s. H2 excitation diagrams show temperatures of 300-600 K and column densities varying across the remnant.
Herschel far infrared_spectroscopy_of_the_galactic_centerSérgio Sacani
The document summarizes observations from the Herschel Space Observatory of the Galactic Center region, focusing on a spectral scan toward Sagittarius A*. Key findings include:
1) Strong emission from atomic fine structure lines and rotationally excited lines of molecules like CO, H2O and HCO+ are detected.
2) The excitation of the CO ladder is consistent with either a hot isothermal gas component at 103.1 K and 104 cm-3, or a distribution of warmer gas at higher densities, with most CO at 300 K.
3) The detected molecular features suggest heating is from a combination of UV irradiation and shocks in the gas, rather than very enhanced X-ray or cosmic
Climatic consequences of regional nuclear conflicts27Nav
This study uses a climate model to simulate the climatic effects of a regional nuclear war between two countries using 100 Hiroshima-sized nuclear weapons on cities in the subtropics. The model finds that the smoke produced by urban fires would cause significant global cooling and reductions in precipitation lasting over a decade. The climate effects are more long-lasting than previous studies due to the smoke being lofted higher into the stratosphere where removal is slower. Reductions in surface sunlight, temperatures, and precipitation of up to 15 W/m^2, 1°C, and 9% respectively are found for several years globally following the conflict.
The document analyzes water vapor weighting functions using radiosonde data from locations between 58°N and 45°S latitude for July and August. It calculates water vapor absorption coefficients and weighting functions at different frequencies and heights. The results show that weighting functions bend more sharply above 2-3 km, indicating better vertical resolution for retrieving atmospheric parameters above this height. Among the frequencies analyzed, 23.834 GHz provided the best vertical resolution above 2-3 km based on the bending of its weighting function curves.
Use of atomic spectra for detection and determinationZainUIabedeen
Atomic spectra is the spectrum of electromagnetic radiation emitted or absorbed during electron transitions between energy levels within an atom. Each element has a characteristic atomic spectrum that can be used to identify it. There are two main types of atomic spectra: emission spectra produced when excited electrons return to lower energy states, and absorption spectra produced when electrons absorb radiation and move to higher energy states. Atomic spectra can be used for a variety of purposes including detecting elements and isotopes, determining the composition of materials like inorganic fertilizers and natural waters, and analyzing biological samples like blood, cerebrospinal fluid, and fingernails.
Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanetGOASA
1) The transmission spectrum of the exoplanet HAT-P-11b was observed using Hubble and Spitzer space telescopes.
2) Water vapor absorption was detected at 1.4 micrometers in the atmosphere, indicating a clear atmosphere down to 1 mbar pressure.
3) The detection of water vapor and relatively large atmospheric scale height places an upper limit on the abundance of heavy elements in the atmosphere of around 700 times the solar value, consistent with core accretion planet formation theories.
The document discusses a study of the relationship between coronal dimmings and coronal mass ejections (CMEs) associated with solar flares. An IDL program was written to analyze iron light curves from 55 flares exhibiting dimmings using SDO-EVE data. Correlations between flare parameters (duration, depth, slope) and CME parameters (velocity, mass) were computed, finding the slope of dimming correlated strongest with CME initial velocity, suggesting a relationship between dimming rate and CME launch speed.
The wonderful complexity_of_the_mira_ab_systemSérgio Sacani
The ALMA observations of the Mira AB binary system reveal an amazingly complex circumstellar environment shaped by multiple dynamical processes. In the blue wing of the CO emission line, opposing large arcs form a bubble structure around Mira A, possibly created by the wind from Mira B blowing into Mira A's expanding envelope. In the main line component, spiral arcs are seen around Mira A that appear relatively flat and oriented in the orbital plane. An accretion wake is also visible trailing Mira B. The companion is marginally resolved with a separation of 0.487 arcseconds from Mira A.
mass spectrometry for pesticides residue analysis- L2sherif Taha
This is the second lecture in series of lectures on mass spectrometry for pesticides residue analysis. This lecture (2) include: Electron ionization and Chemical ionization
The GRIPS instrument is a balloon-borne solar observatory designed to study particle acceleration during solar flares using imaging, spectroscopy, and polarimetry from 20 keV to 10 MeV. It successfully completed its first Antarctic long-duration balloon flight in January 2016, observing 21 C-class flares. GRIPS aims to address outstanding questions about the spatial separation of electron and ion emission sites, ion acceleration, electron anisotropy, and composition changes during flares. It utilizes new technologies like 3D position-sensitive germanium detectors and a single-grid modulator to improve on the resolution of previous instruments like RHESSI.
Meridional brightness temperatures were measured on the surface of Titan during the 2004–2014 portion of the
Cassini mission by the Composite Infrared Spectrometer. Temperatures mapped from pole to pole during five twoyear
periods show a marked seasonal dependence. The surface temperature near the south pole over this time
decreased by 2 K from 91.7±0.3 to 89.7±0.5 K while at the north pole the temperature increased by 1 K from
90.7±0.5 to 91.5±0.2 K. The latitude of maximum temperature moved from 19 S to 16 N, tracking the subsolar
latitude. As the latitude changed, the maximum temperature remained constant at 93.65±0.15 K. In 2010
our temperatures repeated the north–south symmetry seen by Voyager one Titan year earlier in 1980. Early in the
mission, temperatures at all latitudes had agreed with GCM predictions, but by 2014 temperatures in the north were
lower than modeled by 1 K. The temperature rise in the north may be delayed by cooling of sea surfaces and moist
ground brought on by seasonal methane precipitation and evaporation.
Titan’s aerosol and stratospheric ice opacities between 18 and 500 μm vertic...Sérgio Sacani
This document is an accepted manuscript for publication in Icarus that summarizes research analyzing data from the Cassini CIRS instrument to characterize Titan's stratospheric aerosols and ices between 18-500 μm. The research finds that aerosols are well-mixed from the surface to 300 km altitude, while nitrile ice clouds (likely HCN and HC3N) appear centered around 90 km. There is also evidence of an ice cloud layer at 60 km that may be C2H6 ice. Volume extinction coefficients derived from CIRS data are compared to those from DISR, finding particle size ratios consistent with sub-micron aerosols and ice particle effective radii of only a few microns.
The dispersion–brightness relation for fast radio bursts from a wide-field su...Sérgio Sacani
Despite considerable efforts over the past decade, only 34 fast radio
bursts—intense bursts of radio emission from beyond our Galaxy—
have been reported1,2
. Attempts to understand the population as a
whole have been hindered by the highly heterogeneous nature of the
searches, which have been conducted with telescopes of different
sensitivities, at a range of radio frequencies, and in environments
corrupted by different levels of radio-frequency interference
from human activity. Searches have been further complicated by
uncertain burst positions and brightnesses—a consequence of the
transient nature of the sources and the poor angular resolution of
the detecting instruments. The discovery of repeating bursts from
one source3
, and its subsequent localization4
to a dwarf galaxy at a
distance of 3.7 billion light years, confirmed that the population
of fast radio bursts is located at cosmological distances. However,
the nature of the emission remains elusive. Here we report a well
controlled, wide-field radio survey for these bursts. We found 20,
none of which repeated during follow-up observations between
185–1,097 hours after the initial detections. The sample includes
both the nearest and the most energetic bursts detected so far. The
survey demonstrates that there is a relationship between burst
dispersion and brightness and that the high-fluence bursts are
the nearby analogues of the more distant events found in highersensitivity,
narrower-field surveys5
.
This research summarizes measurements taken during the COPE-MED field campaign to better understand warm rain processes and entrainment effects on heavy precipitation. LWC probes were compared and generally agreed well, though the PVM overestimated LWC at higher concentrations and smaller diameters. A LWC survey with vertical statistics was conducted. Analysis of droplet spectra bimodality from low-precipitation cases found evidence of bimodality but secondary activation was unlikely the cause, with the bimodality mechanism remaining unclear. Future COPE analysis will utilize these LWC and bimodality findings to evaluate hypotheses regarding warm rain processes and entrainment impacts on heavy precipitation.
1) The document reports on phase-resolved emission spectroscopy observations of the exoplanet WASP-43b using the Hubble Space Telescope.
2) The observations tracked the planet over three full orbits and measured its thermal emission as a function of orbital phase, allowing the researchers to construct a map of the planet's atmospheric thermal structure.
3) The results found large day-night temperature variations at all measured altitudes, with temperature monotonically decreasing with increasing pressure. A low Bond albedo of 0.07-0.18 and offset of the hottest point from the substellar point were also derived.
Mass spectrometry involves ionizing molecule samples and then measuring their mass-to-charge ratios. The samples are bombarded with electrons to produce molecular ions, which then fragment into product ions. These ions are separated based on their mass-to-charge ratios and detected, producing a mass spectrum that shows the abundances of each ion. This spectrum provides structural information about the precursor molecule and can be used to identify unknown compounds. Mass spectrometry is widely applied across many scientific fields including pharmaceutical analysis, environmental testing, and forensics.
Direct detection of the enceladus water torus with herschelSérgio Sacani
The Herschel Space Observatory directly detected the water vapor torus around Saturn's moon Enceladus by observing absorption lines of water vapor against Saturn. Spectroscopic observations with Herschel's HIFI instrument detected water vapor lines at 557, 987, 1113, and 1670 GHz. Modeling of the spectra determined the water vapor has a column density of ~4 × 1013 cm-2 near the equatorial plane and a vertical scale height of ~50,000 km. The water torus appears rotationally cold at 16 K but is dynamically excited with non-Keplerian velocities of ~2 km/s, shaped largely by molecular collisions. Estimates of the influx of torus material into
Water vapor mapping on mars using omega mars expressAwad Albalwi
A systematic mapping of water vapor on Mars has been achieved using the imaging spectrometer OMEGA aboard the Mars Express
spacecraft, using the depth of the 2.6 mm (n1, n3) band of H2O. We report results obtained during two periods: (1) Ls ¼ 330–401
(January–June 2004), before and after the equinox, and (2) Ls ¼ 90–1251, which correspond to early northern summer
The document describes the challenges of measuring dayglow emissions and past attempts to do so. It summarizes:
1) Dayglow emission intensities are very low compared to the strong solar continuum background, making measurements difficult.
2) Past attempts used techniques like high-resolution scanning and subtracting the solar spectrum, but results were ambiguous and contributions from direct sunlight could not be separated.
3) Other techniques tested included using Fabry-Perot etalons and interference filters in series, as well as polarization properties to reduce the background, but definitive dayglow measurements were not obtained.
The document summarizes Spitzer observations of the supernova remnant IC 443. The MIPS images show the remnant's morphology in great detail, resembling a shell or loop. The dust temperature ranges from 18-30 K based on the 70/160um ratio. IRS spectroscopy confirms shock-excited atomic and molecular emission, with shock velocities of 60-90 km/s. H2 excitation diagrams show temperatures of 300-600 K and column densities varying across the remnant.
The document discusses generating ephemerides for asteroids using analytical propagation methods. It begins by introducing the objectives, various coordinate systems, and complexities in determining orbital motion. It then covers the equations of motion for two-body motion and conic orbits. The document describes how to generate ephemerides using analytical techniques by calculating orbital element transformations between time steps. Comparisons to JPL ephemerides for Pallas show errors on the order of 10^-1 to 10^-2 in position and velocity components. While computationally simpler, the two-body model results in significant absolute errors, requiring more detailed force models for precision.
The document discusses supernovae, which occur when high mass stars reach the end of their life. A supernova releases more energy than the star produced over its entire lifetime through nuclear fusion. This energy release allows for the creation of elements heavier than iron. The calculations show that a 10 solar mass star would produce enough energy over its lifetime to power a supernova explosion, with the bulk of energy released being carried away by neutrinos. Neutrinos play a key role in depositing energy into the star's envelope during a supernova.
This document is a summary of a thesis titled "Factors affecting career advancement of nurses in government hospitals". It provides key details about the thesis in 3 paragraphs. The first paragraph provides background information on the topic and objectives. The second paragraph summarizes the methodology, which involved a quantitative survey of 520 nurses. The third paragraph summarizes the main findings, which were that work experience, additional qualifications and good relationships with supervisors were factors that positively influenced career advancement for nurses.
This document provides an overview of comets and their importance. It begins with a brief introduction describing comets as "dirty balls of ice" with tails that form when they pass by the sun. It then discusses the historical observations of comets and modern scientific study of their structure and composition. The document outlines that comets are composed of an icy nucleus surrounded by a coma of gas and dust, and that studying their composition provides insights into the early solar system. It concludes by summarizing several past and present space missions that have visited and imaged comets to learn more about their properties.
1) Researchers observed 15 transits of the exoplanet GJ 1214b using the Hubble Space Telescope to measure its transmission spectrum from 1.1 to 1.7 microns.
2) The transmission spectrum was featureless, inconsistent with cloud-free atmospheres dominated by water, methane, carbon monoxide, nitrogen, or carbon dioxide.
3) The most likely explanation for the featureless spectrum is the presence of high-altitude clouds in the planet's atmosphere, which block the transmission of stellar light through the lower atmosphere.
An absorption profile centred at 78 megahertz in the sky-averaged spectrumSérgio Sacani
1. Scientists detected a flattened absorption profile in the sky-averaged radio spectrum centered at 78 megahertz using the EDGES instrument.
2. The profile is consistent with expectations for absorption by neutral hydrogen during the epoch of first stars, but its amplitude is over twice as large as predicted.
3. This discrepancy suggests the gas was cooler or the background radiation hotter than expected, with only interactions between dark matter and baryons able to explain the observed amplitude.
DEVELOPMENT OF OPTICAL PARAMETER CALCULATIONS OF THE PROBES IN WATERDr. Ved Nath Jha
This document describes the development of optical parameter calculations for probes used in water sensing. Three probes (a, b, c) of varying nanoparticle size were developed and their plasma and collision wavelengths were calculated based on experimental measurements in water and air. The probes showed decreasing collision wavelength but nearly constant plasma wavelength with increasing nanoparticle size. Models were developed to calculate output intensity based on the dielectric constant of the surrounding medium. Distinct dips in output intensity correlated with different dielectric components when mixtures were tested, showing ability to detect multiple impurities simultaneously. The probes function best for dielectric constants between 1.4-2.0 and silver nanoparticles provide sensitivity towards targeted impurities in water quality monitoring.
Pulsar emission amplified and resolved by plasma lensing in an eclipsing binarySérgio Sacani
Radio pulsars scintillate because their emission travels through the
ionized interstellar medium along multiple paths, which interfere
with each other. It has long been realized that, independent of their
nature, the regions responsible for the scintillation could be used
as ‘interstellar lenses’ to localize pulsar emission regions1,2
. Most
such lenses, however, resolve emission components only marginally,
limiting results to statistical inferences and detections of small
positional shifts3–5
. As lenses situated close to their source offer
better resolution, it should be easier to resolve emission regions of
pulsars located in high-density environments such as supernova
remnants6
or binaries in which the pulsar’s companion has an
ionized outflow. Here we report observations of extreme plasma
lensing in the ‘black widow’ pulsar, B1957+20, near the phase in its
9.2-hour orbit at which its emission is eclipsed by its companion’s
outflow7–9
. During the lensing events, the observed radio flux is
enhanced by factors of up to 70–80 at specific frequencies. The
strongest events clearly resolve the emission regions: they affect the
narrow main pulse and parts of the wider interpulse differently. We
show that the events arise naturally from density fluctuations in
the outer regions of the outflow, and we infer a resolution of our
lenses that is comparable to the pulsar’s radius, about 10 kilometres.
Furthermore, the distinct frequency structures imparted by the
lensing are reminiscent of what is observed for the repeating fast
radio burst FRB 121102, providing observational support for the
idea that this source is observed through, and thus at times strongly
magnified by, plasma lenses10
This literature survey discusses plasma spectroscopy and its applications. Spectroscopy is used to characterize plasmas by determining properties like electron temperature and density. Spectroscopy works by analyzing the emissions from plasmas using instruments like monochromators and detectors. Collisional radiative models are then used to identify emitting species and plasma characteristics based on the emission data. The document provides background on the science of spectroscopy and plasmas. It also discusses experimental setup, techniques for analyzing low temperature plasma emissions, and applications of plasma spectroscopy in various fields.
This document summarizes several abstracts presented at the AIP Bi-Annual Postgraduate Conference on September 7-8, 2001. The abstracts covered topics related to gravitational waves, opto-acoustic interactions, quantum mechanics, spin waves, frequency sources, phonon lasers, nanostructure fabrication, and silicon nanowire growth. Experimental and theoretical work was presented across various fields of physics including general relativity, quantum physics, condensed matter physics, and nanotechnology.
1. This document describes a multiwavelength campaign on the Seyfert 1 galaxy Mrk 509 using five satellites and two ground-based facilities.
2. The campaign aims to study several open questions about active galactic nuclei (AGN), including the location and physics of outflows from AGN, the nature of continuum emission, the geometry and physical state of the X-ray broad emission line region, and the Fe-K line complex.
3. The observations cover more than five decades in frequency, from 2 μm to 200 keV, and include a simultaneous set of deep XMM-Newton and INTEGRAL observations over seven weeks. This allows the authors to disentangle different components and study time variability
This document presents observations from the VLT X-shooter instrument of two quasars, SDSS J1106+1939 and SDSS J1512+1119. For SDSS J1106+1939, a broad absorption line (BAL) outflow is detected with a kinetic luminosity of at least 10^46 erg/s, which is 5% of the quasar's bolometric luminosity. This outflow has a velocity of ~8000 km/s and is located ~300 pc from the quasar. For SDSS J1512+1119, two separate outflows are detected using the same technique, with distances ranging from 100-2000 pc from the central source. The distances of the outflows
Field ion microscopy uses a high electric field to ionize gas atoms on the tip of a sample, which are then detected to create an atomic-scale image of the sample surface. Infrared spectroscopy analyzes the absorption of infrared light by molecules to determine their structure. Raman spectroscopy analyzes the inelastic scattering of monochromatic light when it interacts with molecular vibrations, rotations, and other low frequency modes to provide molecular fingerprint information. Both techniques produce spectra that can be used to identify chemicals based on the frequencies of molecular vibrations they produce.
This document describes a study that determines the relative abundances of elements in the warm absorber of the active galaxy Mrk 509 using X-ray spectra from XMM-Newton and Chandra observations. The study finds relative abundances that are consistent with proto-solar values, with the exception of sulfur which is slightly underabundant. Specifically, the study measures relative abundances of carbon, nitrogen, neon, magnesium, silicon, sulfur, calcium, and iron with respect to oxygen. These abundances provide information about the enrichment processes in the host galaxy and can be compared to abundances measured in other galaxies to study abundance evolution.
1. This paper presents results from a 600 ks XMM-Newton observation of Mrk 509 as part of a large multiwavelength campaign.
2. The high quality spectrum allows an unprecedented investigation of the ionized outflow through the detection of multiple absorption lines.
3. The outflow is found to consist of at least two velocity components that have been observed previously, as well as a tentative high velocity component. Discrete ionization components are detected spanning four orders of magnitude in ionization parameter.
Phosphine gas in the cloud decks of VenusSérgio Sacani
The document reports the discovery of phosphine (PH3) gas in Venus's atmosphere based on millimeter-wave spectral detections from the JCMT and ALMA telescopes. Detections of absorption at the predicted wavelength of the PH3 1-0 rotational transition were observed to be consistent with Venus' velocity. The inferred PH3 abundance is approximately 20 parts per billion. However, the presence of PH3 in Venus' atmosphere is currently unexplained as there are no known abiotic production mechanisms for PH3 under Venus' atmospheric conditions. The PH3 could potentially originate from unknown photochemistry or geochemistry, or from the presence of life by analogy to biological PH3 production on Earth. Further observations are needed to confirm the detection
A mathematical algorithm was developed to calculate effective density values within Apollo lunar core samples using digitized radiographs. Code was written in MATLAB to produce density maps based on the algorithm. Factors like varying X-ray intensities due to the Inverse Square Law and different material thicknesses were accounted for. The resulting density maps provide reasonable values compared to previously measured bulk densities, but more information is needed to address issues in radiography and the physical parameters of the X-ray setup. With this additional information, density values as a function of depth and porosity can be accurately evaluated.
43 Beam asymmetry Σ measurements on the π- Photoproduction off neutrons - Phy...Cristian Randieri PhD
The document summarizes measurements of the beam asymmetry Σ in the photoproduction of negative pions off neutrons using the Graal collaboration's polarized photon beam and detector setup. Key points:
- Beam asymmetry measurements were made for the reaction γn → π−p from 700-1500 MeV photon energy and over a wide angular range.
- Event identification and background reduction was achieved through constraints on additional neutral particles, coplanarity of pion and proton, Fermi momentum reconstruction, and a multivariate cut.
- Results are compared to recent partial wave analyses to help constrain isospin transition amplitudes in pion photoproduction on nucleons.
This document provides an overview of UV-Visible spectroscopy. It discusses how UV radiation causes electronic transitions in molecules, which can be observed via absorption spectroscopy. The instrumentation used includes sources of UV and visible light, a monochromator to select wavelengths, and a detector. Samples are dissolved and placed in transparent cuvettes for analysis. Spectra are recorded as absorbances and show absorption bands corresponding to electronic transitions. UV-Vis is useful for structure elucidation and quantitative analysis.
1. Infrared spectroscopy analyzes molecular vibrations and rotations that occur when molecules absorb infrared radiation.
2. Different types of molecular vibrations like stretching and bending occur at characteristic frequencies that can identify functional groups and molecular structure.
3. The document discusses various spectroscopic techniques like fluorescence, X-ray, UV-Vis, IR, Raman, and NMR spectroscopy and their applications in chemistry.
Dense m agnetized_plasma_associated_with_afast_radio_burstSérgio Sacani
Astrônomos detectaram uma chamada rápida explosão de rádio a cerca de 6 bilhões de anos-luz de distância, uma das menos de duas dezenas desse tipo de evento descobertos nos últimos dez anos, e dessa vez eles têm pistas sobre a fonte.
As rápidas explosões de rádio, ou FRBs, são misteriosas explosões de energia que ocorrem no espaço e que aparecem como rápidos flashes de ondas de rádio nos telescópios da Terra. Essas explosões têm intrigado os astrônomos desde que elas foram reportadas pela primeira vez a uma década atrás. Embora somente 16 dessas explosões tenham sido registradas, eles acreditam que possam existir milhares delas por dia.
Vasculhando mais de 650 horas de dados obtidos pelo Telescópio Green Bank, do NRAO, um grupo internacional de astrônomos descobriu o mais detalhado registro já feito até hoje de uma FRB.
Students aged 12 to 18 observed the Big Bang using an 11-inch telescope. They measured redshifts of galaxies and deduced quantitative conclusions about the age of the universe and density of dark matter. Key findings included:
- Measuring significant redshifts of 0.0077 and 0.003 for galaxies NGC 3516 and M66, matching literature values.
- Interpreting the main emission line at 6590 Angstroms as hydrogen-alpha, indicating a redshift of 0.0077 for NGC 3516.
- Concluding the Big Bang observations were highly significant based on statistical analysis, despite limitations of the small telescope.
A 2 4_determination_of_the_local_value_of_the_hubble_constantSérgio Sacani
We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to
reduce the uncertainty in the local value of the Hubble constant from 3.3% to 2.4%.
The bulk of this improvement comes from new, near-infrared observations of Cepheid
variables in 11 host galaxies of recent type Ia supernovae (SNe Ia), more than doubling
the sample of reliable SNe Ia having a Cepheid-calibrated distance to a total of 19; these
in turn leverage the magnitude-redshift relation based on 300 SNe Ia at z <0.15. All
19 hosts as well as the megamaser system NGC4258 have been observed with WFC3
in the optical and near-infrared, thus nullifying cross-instrument zeropoint errors in the
relative distance estimates from Cepheids. Other noteworthy improvements include a
33% reduction in the systematic uncertainty in the maser distance to NGC4258, a larger
sample of Cepheids in the Large Magellanic Cloud (LMC), a more robust distance to
the LMC based on late-type detached eclipsing binaries (DEBs), HST observations of
Cepheids in M31, and new HST-based trigonometric parallaxes for Milky Way (MW)
Cepheids.
Dynamic light scattering can be used to measure the diffusion of small particles undergoing Brownian motion. An experiment is described that uses a laser, sample cell containing diffusing particles, lenses, photodetector, and photon correlator. The photodetector records the scattered light as pulses, which are clustered for moving particles due to the Doppler effect. The photon correlator measures the intensity correlation function over time to determine the decay time of fluctuations, which relates to particle size and diffusion coefficient according to equations presented. Dynamic light scattering is a powerful technique for studying phenomena involving fluctuations at the microscopic scale.
Similar to INCIDENCE OF ABSORPTION AT THE INTERFACE OF GALAXIES AND IGM (20)
7. Distribution of the baryonic matter:
~ 6-10 % are in the form of galaxies.
=> 90-93 % of the baryonic matter are in the form of IGM
8.
9. Owing to the high temperature of the IGM, the UV region of the
electromagnetic spectra is the best region to study it.
10. Owing to the high temperature of the IGM, the UV region of the
electromagnetic spectra is the best region to study it.
Cosmic Origin Spectrograph- Aboard the Hubble Space Telescope
COS is capable of producing high sensitivity medium and low
resolution far-UV and near-UV spectra
11. The data was obtained from the public archive of the COS (Cosmic Origin
Spectrograph) available at Multi-mission Archive (MAST) at Space Telescope
Science Institute (STScI) webpage : http://archive.stsci.edu/
12. The data was obtained from the public archive of the COS (Cosmic Origin
Spectrograph) available at Multi-mission Archive (MAST) at Space Telescope
Science Institute (STScI) webpage : http://archive.stsci.edu/
COS Grating Parameters
15. Data Analysis
Step1: The data is converted into either ASCII or the .sav format depending upon the
requirement.
Step2: The data is re-binned.
Step3: Then various rebinned files are co-added with the exposure time as the
weightage factor.
Step4: The spectra is then plotted using the co-added files and from the spectra the
continuum normalized spectra is obtained on which all the final analysis is done.
17. Line Measurements Using Apparent Optical
Depth Method
The direct integration of the observed optical path difference is done
18. Line Measurements Using Apparent Optical
Depth Method
The direct integration of the observed optical path difference is done
19. Line Measurements Using Apparent Optical
Depth Method
The first moment of the optical depth gives the central velocity of the absorption line
20. Line Measurements Using Apparent Optical
Depth Method
The first moment of the optical depth gives the central velocity of the absorption line
And we get the Doppler width from the second moment of the apparent optical depth
21. Line Measurements Using Apparent Optical
Depth Method
The first moment of the optical depth gives the central velocity of the absorption line
And we get the Doppler width from the second moment of the apparent optical depth
Where,
22. Line Measurements Using Apparent Optical
Depth Method
The general expression for the calculation of equivalent width is
Where f(v) is the continuum normalised flux of the spectra in the velocity space.
29. Observations and Results
If the line is clearly resolved, a value of the parameter can be obtained. In case of
the absence of the absorption line or unresolved line, only an upper limit could be
calculated.
30. Observations and Results
If the line is clearly resolved, a value of the parameter can be obtained. In case of
the absence of the absorption line or unresolved line, only an upper limit could be
calculated.
The table shows the measured values and the upper limit of the various parameters
(Wr (mA)= Equivalent width in milli-angstrom, ba= Doppler parameter)
31. Observations and Results
The table shows a list of the line of the sights, associated absorbers, impact parameters
and the equivalent width.
33. Conclusion
1. There is no obvious relation between the impact parameters of the galaxies and the
equivalent width of the absorption lines.
34. Conclusion
1. There is no obvious relation between the impact parameters of the galaxies and the
equivalent width of the absorption lines.
2. Based on the measurement of the Doppler parameter, the average value of the
temperature was found to be 5 x 10^4 K, which is consistent with the temperature of the
photoionized component of the IGM.
35. Conclusion
1. There is no obvious relation between the impact parameters of the galaxies and the
equivalent width of the absorption lines.
2. Based on the measurement of the Doppler parameter, the average value of the
temperature was found to be 5 x 10^4 K, which is consistent with the temperature of the
photoionized component of the IGM.
3. Although in none of the case any other absorption line by any metal ion is detected,
from the measurement an upper limit was calculated for the ions in all the cases
and is in agreement with the model of cosmic abundance percentage. The absence of
metal absorption is consistent with low metallicity (of ~1/10 solar) typical of low-z
IGM.
36. Conclusion
1. There is no obvious relation between the impact parameters of the galaxies and the
equivalent width of the absorption lines.
2. Based on the measurement of the Doppler parameter, the average value of the
temperature was found to be 5 x 10^4 K, which is consistent with the temperature of the
photoionized component of the IGM.
3. Although in none of the case any other absorption line by any metal ion is detected,
from the measurement an upper limit was calculated for the ions in all the cases
and is in agreement with the model of cosmic abundance percentage. The absence of
metal absorption is consistent with low metallicity (of ~1/10 solar) typical of low-z
IGM.
4. Though as of now, nothing can be said about the relation between the impact parameter
and the equivalent width because of the lack of the number of data points, one
conclusion that can be drawn based on the above graphs is that there is a possibility that
the IGM surrounding the galaxies is patchy.
37. References:
1. Penton, Steven V.; Stocke, John T.; Shull, J. Michael, “The Local Lyα Forest. IV. Space
Telescope Imaging Spectrograph G140M Spectra and Results on the Distribution and
baryon Content of H I Absorbers”, The Astrophysical Journal Supplement Series , 152:29-62,
2004 May.
2. Lehner, N.; Savage, B. D.; Wakker, B. P.; Sembach, K. R.; Tripp, T. M. “Low-
Redshift Intergalactic Absorption Lines in the Spectrum of HE 0226-4110”, The
Astrophysical Journal Supplement Series , 164:1 – 37, 2006 May
3. Blair D. Savage, Kenneth R. Sembach, “The Analysis of Apparent Optical Depth Profiles for
Interstellar Absorption Lines”, The Astrophysical Journal, 379: 245-259,1991 September
20
4. Joel N. Bregman, "The Search for the Missing Baryons at Low Redshift", Annu.
Rev. Astron. Astrophys. 2007. 45:221–59
5. Anand Narayanan, Bart P. Wakker, Blair D. Savage, Brian A. Keeney, J. Michael Shull,
John T. Stocke, and Kenneth R. Sembach, "Cosmic Origins Spectrograph And Fuse
Observations of T ∼ 10^5 K Gas In A Nearby Galaxy Filament", The Astrophysical
Journal, 721:960–974, 2010 October
Afternoon everyone. The aim of my project was to study the incidence of absorption lines at the interface of galaxies and IGM.It was done under the guidance of Dr. Anand Narayanan.
This is how I plan to go about the presentation. I will start with an introduction then go on to discuss the source and type of data used. Then will discuss the data analysis and several steps involved in that. Then I will be discussing the method used for the measurement of various features of interest, discuss the result and then discuss a few conclusion made based on the observations.
One of the key questions that needs to be answered by astrophysicists is what is really out there?
Which immediately leads us to another question, what is it made up of?Without finding the answer to these questions, it is impossible to understand how the universe evolved after the big bang.Until very recently, about four decades ago, astronomers thought that universe was composed entirely of the baryonic matter. However, owing to the recent observations and the data from WMAP and several other satellites, the present day composition of the universe stands at this
The normal matter or the baryonic matter contributes only to roughly 5% of the total energy density. Which means that all the galaxies and the intergalactic medium which we directly observe are but a small fraction of what is really out there. We shall focus on this part of the energy density and see how it is distributed across the cosmos.
The bulk of the material has not collapsed into luminous structures and are in circumgalactic regions and in the unvirialized large-scale intergalactic filaments.
Which emphasise the importance of studying on the IGM.And that is what I did. In my project, I studied the IGM lying just outside the galactic halo with the help of the absorption lines present in the continuum spectra of a background source.
The figure shows a galactic filament.Distribution of galaxies (circles, from NED) and AGNs (stars) in the field of the galaxy filament. The solid black line roughly outlines the filament. Circle sizes are proportional to the D25 diameters of the galaxies, with minimum size for galaxies smaller than 5kpc. Circle colours indicate the galaxy systematic velocities, following to the legend in the right bottom corner.Four sight lines were chosen, depending on the availability of the public data and the presence of a background source.
The data (QSO spectra) which I have used for analysis was recorded by the Cosmic Origins Spectrograph (COS), aboard the Hubble Space Telescope (HST). COS is capable of producing high sensitivity medium and low resolution far-UV and near-UV spectra.
The two detectors and seven diffraction gratings (three for FUV, four for NUV) of COS enable high-sensitivity spectroscopy at low and moderate resolution across the FUV and NUV bands.
The data is downloaded from the website, which in table form looks like this...
The following table shows how the data is recorded and the various parameters involved. There are various other columns which shows the type of aperture used, name of the detector, proposal id, release date etc which I have omitted for the lack of the space.The data comes in the FITS format, which is converted into either ASCII format or .sav format depending on the need.The
Final analysis basically means the search for absorption lines, and once the absorption lines are found with some confidence, measuring the various parameters associated with the absorption lines.
There are several methods available to determine the column density from the absorption line measurement. But we shall focus on the line measurements using the AOD Method.In this method the direct integration of the observed optical path difference is done
And skipping how the formula is derived, the final expression comes out to be like this...So, all that is required is to divide the value of the flux at any point with the value of the continuum normalised flux at that point, and then integrate it over the width of the absorption line.
Which is integrated over the range in which the absorption line is present.
Four sight lines were selected in order to do the study, namely
The x-axis represents the velocity, or variation from the central line, and the y-axis represents the continuum normalised flux of the spectra.The solid vertical line represents where the absorption lines are supposed to be present for each ion.
As can be seen, the lyman alpha absorption lines are clearly identifiable in all the spectra except for that of HE0238-1904.Based on these system plots, the measurements were carried out. In the cases where the absorption line is easily identifiable, a value of the parameter can be obtained, however if the line is absent or is not well resolved only an upper limit can be obtained, for example
For example, in the case of spectra of MS01117.2-2837, the following table gives the list of various parameters calculated
And as is clear from the spectra of system plot of MS017.2-2837, except for HI 1215 line, no other absorption line is present, so only an upper limit on the respective parameters could be placed.The purpose of calculating the equivalent width was to check whether the equivalent widths of the Lyman-alpha lines is showing any apparent correlation with the impact parameters of the sight line with the nearest galaxies in the filament.
As is evident from the figure, there is no apparent relation between the impact parameters and the equivalent width of the absorption lines (lyman alpha). This is in accordance with what has been reported in the literature so far.