Results 21 to 30 of about 1,130 (187)
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. +14 more
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X-Rays from Active Galactic Nuclei [PDF]
Highlights of Astronomy, 1983 Recent X-ray observations of active galactic nuclei and Seyfert galaxies in particular are briefly reviewed. The application of the efficiency limit to rapidly varying luminous sources such as NGC 6814 is discussed. It is argued that the variability and probable MeV spectral turnover imply that most of the electrons which radiate the observed flux are ...
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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.
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X-RAY VARIABILITY AND THE INNER REGION IN ACTIVE GALACTIC NUCLEI [PDF]
The Astrophysical Journal, 2014 32 pages, 11 figures (9 sub-figures); 4 Tables; 1 appendix; published in the Astrophysical ...
P. Mohan, A. Mangalam
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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
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The infrared--X-ray continuum correlation in active galactic nuclei [PDF]
Monthly Notices of the Royal Astronomical Society, 2003 The correlation between the soft X-ray and near infrared emission from AGN is analysed using composite models by the code SUMA. We find new evidences for differences in ranges of parameters which characterize the NLR of Seyfert galaxies and LINERs. Results obtained by modelling the Einstein and the ROSAT samples of galaxies are in full agreement.
Contini, M. +2 more
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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 +3 more
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Soft X-ray active galactic nuclei
The Astrophysical Journal, 1984 The discovery of 10 active galactic nuclei (AGNs) based upon optical observations of Einstein Observatory X-ray sources is reported. The new objects are optically similar to AGNs that have been identified by others with this technique. One notable exception, the quasar E1821 + 643, is associated with a previously unidentified X-ray source detected with
S. H. Pravdo, F. E. Marshall
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The X-Ray Coronae in NuSTAR Bright Active Galactic Nuclei
The Astrophysical Journal, 2022 Abstract We present a systematic and uniform analysis of NuSTAR data of a sample of 60 SWIFT BAT-selected AGNs with 10–78 keV signal-to-noise ratio (S/N) > 50, 10 of which are radio loud. We measure their high-energy cutoff E cut or coronal temperature T e using three different spectral models to ...
Jia-Lai Kang, Jun-Xian Wang
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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. +6 more
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