Results 21 to 30 of about 50,261 (220)

OCCUPATION OF X-RAY-SELECTED GALAXY GROUPS BY X-RAY ACTIVE GALACTIC NUCLEI [PDF]

The Astrophysical Journal, 2012
We present the first direct measurement of the mean halo occupation distribution (HOD) of X-ray-selected active galactic nuclei (AGNs) in the COSMOS field at z ≤ 1, based on the association of 41 XMM and 17 C-COSMOS AGNs with member galaxies of 189 X-ray-detected galaxy groups from XMM-Newton and Chandra data.
Allevato, V., Finoguenov, A., Hasinger, G., Miyaji, T., Cappelluti, N., Salvato, M., Zamorani, G., Gilli, R., George, M., Tanaka, M., Brusa, M., Silverman, J., Civano, F., Elvis, M., Shankar, F.   +14 more
openaire   +8 more sources

X-ray variability time scales in active galactic nuclei [PDF]

Astronomy & Astrophysics, 2009
6 pages, 1 figure, accepted for publication in Astronomy and ...
Ishibashi, W., Courvoisier, T. J. -L.
openaire   +2 more sources

X-rays from active galactic nuclei

The Astrophysical Journal, 1981
Through detailed numerical calculations, we have shown that production of thermal photons at the self-absorbed cyclotron higher harmonics and Comptonization of those soft photons in a hot plasma with the electron temperature 10/sup 9/ K provide a natural mechanism to account for the dominant observed features of the X-ray emission in the active ...
F. Takahara, S. Tsuruta, S. Ichimaru
openaire   +1 more source

X-ray bolometric corrections for Compton-thick active galactic nuclei [PDF]

, 2017
We present X-ray bolometric correction factors, $\kappa_{Bol}$ ($\equiv L_{Bol}/L_X$), for Compton-thick (CT) active galactic nuclei (AGN) with the aim of testing AGN torus models, probing orientation effects, and estimating the bolometric output of the ...
Ballantyne, D. R., Baloković, M., Bauer, F. E., Boorman, P., Brandt, W. N., Brightman, M., Buchner, J., Comastri, A., Del Moro, A., Farrah, D., Gandhi, P., Harrison, F. A., Koss, M., Lanz, L., Masini, A., Ricci, C., Stern, D., Vasudevan, R., Walton, D. J.   +18 more
core   +4 more sources

Identification of four RXTE Slew Survey sources with nearby luminous active galactic nuclei [PDF]

, 2005
Based on RXTE scans and observations with the SWIFT/XRT telescope and INTEGRAL observatory, we report the identification of four X-ray sources discovered during the RXTE Slew Survey of the |b|>10deg sky with nearby (z ~ 0.017-0.098) luminous (log L_2 ...
Dickey, E. Churazov, M. Revnivtsev, Nandra, Revnivtsev, Reynolds, S. Sazonov, S. Trudolyubov, Sazonov, Sazonov, Voges   +10 more
core   +1 more source

The ratio of X-ray-to-optical luminosity for active galactic nuclei [PDF]

Monthly Notices of the Royal Astronomical Society, 1984
On montre que le renforcement apparent du rapport moyen des luminosites RX a optique des noyaux de Seyfert 1, en comparaison avec les QSO radio calmes, peut etre largement, sinon totalement, du a un rougissement interne.
CHENG FZ, Danese, Luigi, DEZOTTI G, LUCCHIN F.   +3 more
openaire   +2 more sources

Transient X-ray Emission from Normal Galactic Nuclei [PDF]

, 2007
X-ray transients appeared in optically non-active galactic nuclei have been observed in recent years. The most popular model explaining this kind of phenomena is the conventional tidal disruption model.
A. Y. L. Wong, Ayal, Bade, Cheng, Cheng, Cheng, Cheng, Donley, Fender, Gallo, Granot, Greiner, Grupe, Grupe, Grupe, Halpern, Huang, Huang, Huang, Huang, K. S. Cheng, Khokhlov, Kim, Komossa, Komossa, Komossa, Lu, Piran, Rees, Sari, Scoville, Ulmer, van Paradijs, Vaughan, Wang, Weingartner, Y. F. Huang, Yuan, Zhang, Zhang   +39 more
core   +1 more source

The Correlation between X-ray spectral slope and FeKalpha line energy in radio-quiet active galactic nuclei

, 2002
A significant correlation between FeKalpha line energy and X-ray spectral slope has been discovered among radio-quiet active galactic nuclei. The ionization stage of the bulk of the FeKalpha emitting material is not the same in all active galactic nuclei
Arnaud K. A., Boller T., Brandt W. N., Fabian A. C., George I. M., Grupe D., Guainazzi M., Guilbert P. W., Gulab Chand Dewangan, Koenig M., Mineo T., Pounds K. A., Reynolds C. S., Winkler H., Wisotzki L.   +14 more
core   +1 more source

A Hard Look at NGC 5347: Revealing a Nearby Compton-thick AGN [PDF]

, 2019
Current measurements show that the observed fraction of Compton-thick (CT) active galactic nuclei (AGN) is smaller than the expected values needed to explain the cosmic X-ray background. Prior fits to the X-ray spectrum of the nearby Seyfert-2 galaxy NGC
Barret, D., Behar, E., Brandt, W. N., Brenneman, L. W., Kaastra, J. S., Kammoun, E. S., Koss, M., Lohfink, A. M., Miller, J. M., Muchotzky, R. F., Oh, K., Proga, Daniel, Stern, D., Zoghbi, A.   +13 more
core   +6 more sources

X-ray variability of active galactic nuclei and the flare model [PDF]

Advances in Space Research, 2006
Short-term variability of X-ray spectra has been reported for several Active Galactic Nuclei. Significant X-ray flux variations are observed within time scales down to 10^4 -- 10^5 seconds. We discuss short variability time scales in the framework of the X-ray flare model, which assumes the release of a large hard X-ray flux above a small portion of ...
Goosmann, R. W., Czerny, B., Dumont, A.-M., Mouchet, M., Rózanska, A., Karas, V., Dovciak, M.   +6 more
openaire   +2 more sources