相关论文: Pressure Ionization Instability: Connection betwee…

We present a deep study of the average hard X-ray spectra of Seyfert galaxies. We analyzed all public INTEGRAL IBIS/ISGRI data available on all the 165 Seyfert galaxies detected at z<0.2. Our final sample consists of 44 Seyfert 1's, 29…

We find a very strong correlation between the intrinsic spectral slope in X-rays and the amount of Compton reflection from a cold medium in Seyfert AGNs and in hard state of X-ray binaries with either black holes or weakly-magnetized…

We present a theoretical framework for the formation of X-ray linear polarization in black hole (BH) source. The X-ray linear polarization originates from up-scatterings of initially soft photons within a hot, optically thick Compton cloud…

We analyze a composite broad-band optical/UV/Xgamma-ray spectrum of the Seyfert 1 galaxy NGC 5548. The spectrum consists of an average of simultaneous optical/IUE/Ginga observations accompanied by ROSAT and GRO/OSSE data from…

The spectra of quasars and NLS1 galaxies show surprising similarity in their spectral shape. They seem to scale only with the accretion rate. This is in contradiction with the simple expectations from the standard disk model which predicts…

We present optical spectropolarimetry of the nuclei of 36 Seyfert 1 galaxies, obtained with the William Herschel and the Anglo-Australian Telescopes from 1996 to 1999. In 20 of these, the optical emission from the active nucleus is…

We report our analysis of X-ray spectra of the Seyfert galaxy IRAS 18325-5926 (=Fairall 49) obtained from various X-ray observatories prior to XMM-Newton, including new results from two RXTE and one BeppoSAX observations. A relatively steep…

Aims: We used data from the 58 month long, continuous Swift/Burst Alert Telescope (BAT) observations of the five brightest Seyfert galaxies at hard X-rays, to study their flux and spectral variability in the 20-100 keV energy band. The…

We assume that the gravitational instability of standard thin accretion disks leads to the Broad Line Regions (BLRs), the B band luminosity comes from standard thin disk and the motion of BLRs is virial. The central black hole masses, the…

We present a model for the different X-ray spectral states displayed by Galactic Black Hole Candidates (GBHC). We discuss the physical and spectral implications for a magnetically structured corona in which magnetic flares result from…

A warm corona at the surface of an accretion disc has been proposed as a potential location for producing the soft excess commonly observed in the X-ray spectra of active galactic nuclei (AGNs). In order to fit the observed data the gas…

In a previous paper (Bian & Zhao 2002), it was suggested that contamination to the luminosity of galactic nucleus from the host galaxies play an important role in determining parameters of the standard $\alpha$ disk for AGNs. Using the…

Recent {\it ASCA} observations confirm the presence of X-ray absorption due to partially ionized gas in many Seyfert 1 galaxies; the so-called warm absorber. Constraints on the location of the warm material are presented with the conclusion…

X-ray observations suggest high compactness of coronae in active galactic nuclei as well as in X-ray binaries. The compactness of the source implies a strong radial dependence in the illumination of the accretion disc. This will, for any…

We discuss two important instability mechanisms that may lead to the limit-cycle oscillations of the luminosity of the accretion disks around compact objects: ionization instability and radiation-pressure instability. Ionization instability…

In active galactic nuclei, X-ray illumination of the accretion disk around a supermassive black hole (SMBH) results in the production of the K$\alpha$ fluorescent line of iron, which provides insights into accretion physics and SMBH spins.…

The magnetic flare avalanches model of Poutanen & Fabian for X-ray variability of accreting black holes is combined with computations of vertical structure of illuminated accretion discs in hydrostatic equilibrium. The latter predict the…

This paper presents a quantification of the X-ray variability amplitude for 79 ASCA observations of 36 Seyfert 1 galaxies. We find that consideration of sources with the narrowest permitted lines in the optical band introduces scatter into…

In this paper we present a temporal and spectral analysis of X-ray data from the XMM and Chandra observations of the ultrasoft and variable Seyfert galaxy RX J1301.9+2747. In both observations the source clearly displays two distinct states…

Narrow-line Seyfert\,1 galaxies (NLS1s) with very small broad-line widths (say, FWHM(\hb) $\la $ 1200\,\kms) represent the extreme type of Seyfert\,1 galaxies that have small black hole masses (\mbh) and/or high Eddington ratios (\redd).…