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Missing Baryons and the Warm-Hot Intergalactic Medium
F. Nicastro, Smita Mathur, Martin Elvis
Stars and gas in galaxies, hot intracluster medium, and intergalactic photo-ionized gas make up at most half of the baryons that are expected to be present in the universe. The maj…
The Near-Infrared Broad Emission Line Region of Active Galactic Nuclei -- I. The Observations
Hermine Landt, Misty C. Bentz, Martin J. Ward +4
We present high quality (high signal-to-noise ratio and moderate spectral resolution) near-infrared (near-IR) spectroscopic observations of 23 well-known broad-emission line active…
Occultation measurement of the size of the X-ray emitting region in the Active Galactic Nucleus of NGC 1365
G. Risaliti, M. Elvis, G. Fabbiano +3
We present an occultation of the central X-ray emitting region in the Seyfert Galaxy NGC 1365. This extreme spectral variation (from Compton-thin to reflection-dominated and back t…
The Compact, Conical, Accretion-Disk Warm Absorber of the Seyfert 1 Galaxy NGC 4051 and its Implications for IGM-Galaxy Feedback Processes
Yair Krongold, Fabrizio Nicastro, Martin Elvis +4
(Abridged) Using a 100 ks XMM-Newton exposure of NGC 4051, we show that the time evolution of the ionization state of the X-ray absorbers in response to the rapid and highly variab…
Time-Evolving Photoionization: the Thin and Compact X-Ray Wind of NGC 4051
Fabrizio Nicastro, Yair Krongold, Martin Elvis +3
We discuss the power of time-evolving photoionization as a diagnostic tool to measure the electron density of photoionized gas. We apply this technique to a XMM-Newton observation…
A deep Chandra, VLA and Spitzer IRAC study of the very low luminosity nucleus of the elliptical NGC821
S. Pellegrini, A. Siemiginowska, G. Fabbiano +5
The relatively nearby (distance=24.1 Mpc) elliptical galaxy NGC821 hosts an extreme example of a quiescent central massive black hole, for which deep Chandra observations revealed…