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A Mass Measurement for the Missing Baryons in the Warm-Hot Intergalactic Medium via the X-ray Forest
F. Nicastro, S. Mathur, M. Elvis +7
Recent Cosmological measurements indicate that baryons comprise about four percent of the total mass-energy density of the Universe, which is in accord with the predictions arising…
Opacity Variations in the Ionized Absorption in NGC 3783: A Compact Absorber
Y. Krongold, F. Nicastro, N. S. Brickhouse +2
We show that the Fe (VII-XII) M-shell unresolved transition array (UTA) in the NGC 3783 900 ks Chandra HETGS observation clearly changes in opacity in a timescale of 31 days respon…
Chandra discovery of activity in the quiescent nuclear black hole of NGC821
A. Baldi, G. Fabbiano, S. Pellegrini +4
We report the results of the Chandra ACIS-S observations of the elliptical galaxy NGC 821, which harbors a supermassive nuclear black hole (of 3.5x10^7 solar masses), but does not…
The Ionized Nuclear Environment in NGC 985 as seen by Chandra and BeppoSAX
Y. Krongold, F. Nicastro, M. Elvis +3
(Abridged) We investigate the ionized environment of the Seyfert 1 galaxy NGC 985 with a new Chandra-HETGS observation and an archival BeppoSAX observation. Two absorption componen…
An Unveiling Event in the Type 2 AGN NGC4388: A Challenge for a Parsec Scale Absorber
Martin Elvis, G. Risaliti, F. Nicastro +3
We present two Rossi Xray Timing Explorer (RXTE) PCA observations of the type~2 Seyfert galaxy NGC 4388 caught in an unusual low X-ray absorption state. The observations were trigg…
The Faint X-ray Source Population Near the 3C 295 cluster
V. D'Elia, F. Fiore, M. Elvis +5
We present a statistical analysis of the Chandra observation of the source field around the 3C 295 galaxy cluster (z=0.46). Three different methods of analysis, namely a chip by ch…
Chandra's Discovery of Activity in the Quiescent Nuclear Black Hole of NGC 821
G. Fabbiano, A. Baldi, S. Pellegrini +4
We report the results of the {\it Chandra} ACIS-S observations of the elliptical galaxy NGC 821, which harbors a supermassive nuclear black hole (of ), b…
Extreme Physics via X-rays from Black Holes and `Neutron' Stars
Martin Elvis
A combination of microchannel plate optics and a 32x32 pixel microcalorimeter would allow the successor to the Rossi XTE to explore new domains of spectroscopic timing in a MIDEX c…
Far Ultraviolet Spectroscopic Explorer Spectroscopy of Absorption and Emission Lines from the Narrow-Line Seyfert 1 Galaxy NGC 4051
Shai Kaspi, W. N. Brandt, M. J. Collinge +2
We present three Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the Narrow-Line Seyfert 1 galaxy NGC4051. The most prominent features in the far-ultraviolet (FUV) sp…