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X-ray absorption by the low-redshift intergalactic medium: A numerical study of the Lambda cold dark matter model
theory intergalactic medium
2014/12/24
Using a hydrodynamic simulation of a cold dark matter universe with a cosmological constant, we investigate the "X-ray forest" absorption imprinted on the spectra of background quasars by the interven...
We have observed six clouds along the line of sight toward W49A using the Submillimeter Wave Astronomy Satellite and several ground-based observatories. The ortho-H2O 110 → 101 and OH (1665 and 1667 M...
X-Ray Absorption Line Spectroscopy of the Galactic Hot Interstellar Medium
Cyg X–2 V801 Ara
2014/12/24
We present an X-ray absorption line spectroscopic study of the large-scale hot interstellar medium (HISM) in the Galaxy. We detect Ne IX Kα absorption lines in the Chandra grating spectra of seven Gal...
Warm-hot gas in and around the Milky Way: Detection and implications of OVII absorption toward LMC X-3
LMC X–3 ISM
2014/12/24
X-ray absorption lines of highly ionized species such as O VII at about zero redshift have been firmly detected in the spectra of several active galactic nuclei. However, the location of the absorbing...
X-Ray Absorption Spectroscopy of the Multiphase Interstellar Medium: Oxygen and Neon Abundances
ISM 4U 1820–303
2014/12/24
X-ray absorption spectroscopy provides a powerful tool in determining the metal abundances in various phases of the interstellar medium (ISM). We present a case study of the sight line toward 4U 1820-...
Chandra Detection of Fe XVII in Absorption: Iron Abundance in the Hot Gaseous Interstellar Medium
4U 1820–303 abundances
2014/12/24
The iron depletion level and the gas-phase iron abundance in the hot (~106 K) interstellar medium (ISM) are critical to our understanding of its energy balance as well as the thermal sputtering, cooli...
The Galactic Central Diffuse X-Ray Enhancement: A Differential Absorption/Emission Analysis
3C 273 Mrk 421
2014/12/23
The soft X-ray background shows a general enhancement toward the inner region of the Galaxy. But whether this enhancement is a local feature (e.g., a superbubble within a distance of 200 pc) and/or a ...
Although the existence of large-scale hot gaseous halos around massive disk galaxies has been theorized for a long time, there is yet very little observational evidence. We report the Chandra and XMM-...
We report the first detection of the ground-state rotational transition of the methylidyne cation CH+ towards the massive star-forming region DR 21 with the HIFI instrument onboard the Herschel satell...
The intergalactic medium over the last 10 billion years I: Lyman alpha absorption and physical conditions
intergalactic medium hydrodynamic
2014/12/20
The intergalactic medium (IGM) is the dominant reservoir of baryons at all cosmic epochs. We investigate the evolution of the IGM from z=2-0 in 48 Mpc/h, 110-million particle cosmological hydrodynamic...
USING 21 cm ABSORPTION IN SMALL IMPACT PARAMETER GALAXY-QUASAR PAIRS TO PROBE LOW-REDSHIFT DAMPED AND SUB-DAMPED Ly alpha SYSTEMS
low-redshift damped Lyα (DLA) sub-DLA quasar absorbers
2014/12/20
To search for low-redshift damped Lyα (DLA) and sub-DLA quasar absorbers, we have conducted a 21 cm absorption survey of radio-loud quasars at small impact parameters to foreground galaxies selected f...
A GREEN BANK TELESCOPE SURVEY FOR H I 21 cm ABSORPTION IN THE DISKS AND HALOS OF LOW-REDSHIFT GALAXIES
21 cm absorption survey Green Bank Telescope
2014/12/20
We present an H I 21 cm absorption survey with the Green Bank Telescope (GBT) of galaxy-quasar pairs selected by combining galaxy data from the Sloan Digital Sky Survey (SDSS) and radio sources from t...
Observations of Mg II Absorption Near z ~ 1 Galaxies Selected From The DEEP2 Redshift Survey
Observations Absorption Galaxies Selected Redshift Survey
2011/10/13
We study the frequency of Mg II absorption in the outer haloes of galaxies at z = 0.6 - 1.4 (with median z = 0.87), using new spectra obtained of ten background quasars with galaxy impact parameters o...
The effects of X-ray absorption variability in NGC 4395
galaxies: active – galaxies: individual: NGC 4395 – X-rays: galaxies
2011/10/8
We present a new X-ray analysis of the dwarf Seyfert galaxy NGC 4395, based on two archival XMM-Newton and Suzaku observations. This source is well known for a series of remarkable properties: one of ...
High-ion absorption in the proximate damped Lyman-alpha system toward Q0841+129
quasars: absorption lines – galaxies: high-redshift – galaxies: halos – galaxies: ISM
2011/10/8
We present VLT/UVES spectroscopy of the quasar Q0841+129, whose spectrum shows a proximate damped Lyman-alpha (PDLA) absorber at z=2.47621 and a proximate sub-DLA at z=2.50620, both lying close in red...