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Studies of quasar absorption lines reveal that the low-density intergalactic medium (IGM) at z ~ 3 is enriched to between 10-3 and 10-2 solar metallicity. This enrichment may have occurred in an early...
Observations have established that the diffuse intergalactic medium (IGM) at z ~ 3 is enriched to ~10-2.5 solar metallicity and that the hot gas in large clusters of galaxies (ICM) is enriched to - Z ...
The presence of metals in hot cluster gas and in Lyα absorbers, as well as the mass-metallicity relation of observed galaxies, suggest that galaxies lose a significant fraction of their metals to the ...
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 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...
We report the detection of highly ionized gas at z ~ 0 seen in resonant UV and X-ray absorption lines toward the z = 0.03 blazar Mrk 421. A total of 13 X-ray and three UV lines were measured (or upper...
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-...
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...
We present Wide Field Camera 3 images taken with the Hubble Space Telescope within a single field in the southern grand design star-forming galaxy M83. Based on their size, morphology, and photometry ...
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...
We present new Green Bank Telescope (GBT) 21 cm neutral hydrogen (H I) observations of a complete distance-limited sample of 22 Hickson Compact Groups (HCGs) with at least four true members. We detect...
The multivariate technique of principal component analysis (PCA) is a powerful statistical tool with which to describe spectral line imaging observations of the molecular interstellar medium. In parti...
Caltech astronomers have taken unprecedented images of the intergalactic medium (IGM)—the diffuse gas that connects galaxies throughout the universe—with the Cosmic Web Imager, an instrument designed ...
This work measures the evolution of the iron content in galaxy clusters by a rigorous analysis of the data of 130 clusters at 0.1difficult by a) the low signal-to-noise ratio...
The gamma-ray sky >100 MeV is dominated by the diffuse emissions from interactions of cosmic rays with the interstellar gas and radiation fields of the Milky Way. Observations of these diffuse emissio...

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