Search Publications
On the Absorption of X-Rays in the Interstellar Medium
McCray, R.; Wilms, J.; Allen, A.
We present an improved model for the absorption of X-rays in the interstellar medium (ISM) intended for use with data from future X-ray missions with larger effective areas and increased energy resolution such as Chandra and the X-Ray Multiple Mirror mission, in the energy range >~100 eV. Compared with previous work, our formalism includes rece…
Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301
Arav, N.; Elvis, M.; Peterson, B. M. +14 more
We present a deep ASCA observation of a broad absorption line quasar (BALQSO) PG 0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (N…
Detection of the Entropy of the Intergalactic Medium: Accretion Shocks in Clusters, Adiabatic Cores in Groups
Tozzi, Paolo; Norman, Colin; Scharf, Caleb
The thermodynamics of the diffuse, X-ray-emitting gas in clusters of galaxies is linked to the entropy level of the intracluster medium. In particular, models that successfully reproduce the properties of local X-ray clusters and groups require the presence of a minimum value for the entropy in the center of X-ray halos. Such a minimum entropy is …
Probing Cosmology with the X-Ray Forest
Canizares, Claude R.; Fang, Taotao
There is a growing consensus that in the present universe most baryons reside in galaxy clusters and groups in the form of highly ionized gas at temperatures of 106-108 K. The H-like and He-like ions of the heavy elements can produce absorption features-the so-called ``X-ray forest''-in the X-ray spectrum of a background quas…