Results 11 to 20 of about 274,748 (260)

Radiation pressure acceleration by X-rays in active galactic nuclei [PDF]

Monthly Notices of the Royal Astronomical Society, 2001
We present calculations of the dynamics of highly ionized gas clouds that are confined by external pressure, and are ionized by AGN continuum. We focus on the gas that is seen in absorption in the X-ray spectrum of many AGN and show that such gas can reach hydrostatic equilibrium under various conditions. The principal conclusion is that the clouds can
Hagai Netzer, Doron Chelouche
openaire   +5 more sources

Testing a model of variability of X-ray reprocessing features in Active Galactic Nuclei [PDF]

Mon.Not.Roy.Astron.Soc. 325 (2001) 197, 2001
A number of recent results from X-ray observations of Active Galactic Nuclei involving the Fe K alpha line (reduction of line variability compared to the X-ray continuum variability, the X-ray ``Baldwin effect'') were attributed to a presence of a hot, ionized skin of an accretion disc, suppressing emission of the line.
P. T. Życki, A. Roza ska
arxiv   +3 more sources

The X-Ray Luminosity Function of Active Galactic Nuclei [PDF]

arXiv, 1999
We derive an X-ray luminosity function for active galactic nuclei (AGN) that accounts for the X-ray source counts in the 0.5-2.0 and 2-10 keV energy ranges, the redshift distribution of AGNs in the ROSAT Deep Survey (RDS), as well as the X-ray background (XRB) from 1-10 keV.
Schmidt, M., Giacconi, R., Hasinger, G., Truemper, J., Zamorani, G.   +4 more
arxiv   +3 more sources

X-Ray Evolution of Active Galactic Nuclei and Hierarchical Galaxy Formation [PDF]

, 2004
We have incorporated the description of the X-ray properties of Active Galactic Nuclei (AGNs) into a semi-analytic model of galaxy formation, adopting physically motivated scaling laws for accretion triggered by galaxy encounters.
A. Cavaliere, Fabrizio Fiore, G. C. Perola, G. C. Perola, Nicola Menci   +4 more
core   +3 more sources

X-ray active galactic nuclei in the core of the Perseus cluster [PDF]

Monthly Notices of the Royal Astronomical Society, 2007
We present a study of the X-ray emission from the nuclei of galaxies observed in the core of the Perseus cluster in a deep exposure with Chandra. Point sources are found coincident with the nuclei of 13 early-type galaxies, as well as the central galaxy NGC1275. This corresponds to all galaxies brighter than M_B = -18 in the Chandra field. All of these
S. Santra, Andrew C. Fabian, Jeremy S. Sanders   +2 more
openaire   +5 more sources

Several New Active Galactic Nuclei Among X-ray Sources Detected by INTEGRAL and SWIFT Observatories [PDF]

, 2008
We present the results of the optical identifications of a set of X-ray sources from the all-sky surveys of INTEGRAL and SWIFT observatories. Optical data were obtained with Russian-Turkish 1.5-m Telescope (RTT150).
A. V. Mescheryakov, B. T. Makaryan, C. Motch, D. G. Monet, D. J. Schlegel, I. F. Bikmaev, I. F. Bikmaev, I. F. Bikmaev, M. D. Bicay, M. G. Revnivtsev, M. N. Pavlinsky, M. Revnivtsev, N. Masetti, P. Massey, R. A. Burenin, R. A. Sunyaev, R. Krivonos, S. Sazonov, S. Sazonov, S. Veilleux, S. Yu. Sazonov, T. M. Heckman, W. Voges   +22 more
core   +4 more sources

The Lively Accretion Disk in NGC 2992. III. Tentative Evidence of Rapid Ultrafast Outflow Variability

The Astrophysical Journal, 2023
We report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert galaxy NGC 2992, observed at one of its highest flux levels in the X-rays.
Alfredo Luminari, Andrea Marinucci, Stefano Bianchi, Barbara de Marco, Chiara Feruglio, Giorgio Matt, Riccardo Middei, Emanuele Nardini, Enrico Piconcelli, Simonetta Puccetti, Francesco Tombesi   +10 more
doaj   +1 more source

X-Ray Observations of Active Galactic Nuclei [PDF]

Symposium - International Astronomical Union, 1983
HEAO 1 A2 and Einstein SSS spectral observations of Seyfert galaxies and BL Lac objects suggest that in both cases, the X-ray emission is due to relativistic particles. The five BL Lac objects have very soft spectra and at higher energies (above 10 keV) may have hard tails.
Richard Mushotzky, Allyn F. Tennant, C. Megan Urry, Elihu Boldt, Stephen S. Holt   +4 more
openaire   +2 more sources

Narrow Fe–Kα Reverberation Mapping Unveils the Deactivated Broad-line Region in a Changing-look Active Galactic Nucleus

The Astrophysical Journal, 2023
“Changing-look active galactic nuclei” (CLAGNs) are known to change their apparent types between types 1 and 2, usually accompanied by a drastic change in their luminosity on timescales of years.
Hirofumi Noda, Taisei Mineta, Takeo Minezaki, Hiroaki Sameshima, Mitsuru Kokubo, Taiki Kawamuro, Satoshi Yamada, Takashi Horiuchi, Hironori Matsumoto, Makoto Watanabe, Kumiko Morihana, Yoichi Itoh, Koji S. Kawabata, Yasushi Fukazawa   +13 more
doaj   +1 more source

Clustering of X-ray selected active galactic nuclei [PDF]

Monthly Notices of the Royal Astronomical Society, 1998
A total of 235 Active Galactic Nuclei (AGN) from two different soft X-ray surveys (the ROSAT Deep Survey -DRS- and the ROSAT International X-ray Optical Survey -RIXOS-) with redshifts between 0 and 3.5 are used to study the clustering of X-ray selected AGN and its evolution.
M. J. Page, Guenther Hasinger, Xavier Barcons, Xavier Barcons, Keith O. Mason, Richard G. McMahon, Jonathan P. D. Mittaz, Francisco J. Carrera, Francisco J. Carrera, Andrew C. Fabian   +9 more
openaire   +4 more sources