Related papers: An X-ray Spectral Model for Compton-Thick Toroidal…

We compute rest-frame reflection spectra and the corresponding energy-dependent linear polarization degree and angle for (un)polarized single-temperature blackbody spectra impinging on a partially ionized constant-density optically thick…

We propose a theoretical model to explain the spectrum of the quasar PG1211+143 emitted in the Optical/X-ray bands. In particular, we suggest that the inner accretion disk may develop a warm, optically thick skin, which produces a profound…

We calculate the radiation spectrum and its time variability of the black hole accretion disk-corona system based on the three-dimensional magnetohydrodynamic simulation. In explaining the spectral properties of active galactic nuclei…

Relativistic reflection features are commonly observed in the X-ray spectra of stellar-mass and supermassive black holes and originate from illumination of the inner part of the accretion disk by a hot corona. All the available relativistic…

We present the broad band analysis of two BeppoSAX observations of the Sy 1 Mkn509. In 2000 the source was in a typical flux state, F{2-10keV}=2.7x10^{-11}erg cm^{-2} s^{-1}, while in 1998 it was found in a high flux state,…

We present new estimates on the fraction of heavily X-ray obscured, Compton-thick (CT) active galactic nuclei (AGNs) out to a redshift of $z \leq$ 0.8. From a sample of 540 AGNs selected by mid-IR (MIR) properties in observed X-ray survey…

We present the first contemporaneous NICER and NuSTAR analysis of the low-mass X-ray binary Serpens X-1 obtained in June 2023, performing broadband X-ray spectral analysis modeling of the reprocessed emission with RELXILLNS from $0.4-30$…

X-ray polarimetric missions planned for this decade will significantly enhance our knowledge of compact accreting sources. Observations of the X-ray polarization signal from active galactic nuclei (AGNs) or X-ray binary systems (XRBs) will…

X-ray illumination of accretion disks is an invaluable diagnostic of the structure of these disks because of the associated iron K$\alpha$ emission. Here we point out that the resulting reflected spectra depend very sensitively on the…

We analyse a large number ($> 500$) pointed RXTE observations of Cyg X-1 and model the spectrum of each one. A subset of the observations for which there is simultaneous reliable measure of the hardness ratio by the All Sky Monitor, shows…

Numerous X-ray spectral models have been developed to model emission reprocessed by the torus of an active galactic nucleus (AGN), e.g., UXCLUMPY, CTORUS, and MYTORUS. They span a range of assumed torus geometries and morphologies-some…

We analysed a dedicated NuSTAR observation of the neutron-star low-mass X-ray binary Z-source GX 13+1 to study the timing and spectral properties of the source. From the colour-colour diagram, we conclude that during that observation the…

The covering factor of Compton-thick obscuring material associated with the torus in active galactic nuclei (AGN) is at present best understood through the fraction of sources exhibiting Compton-thick absorption along the line of sight…

We present a detailed X-ray spectral analysis of the sources in the 1Ms catalog of the Chandra Deep Field South (CDFS) taking advantage of optical spectroscopy and photometric redshifts for 321 sources. As a default spectral model, we adopt…

We present a series of monitoring observations of the ultrasoft broad-line AGN RE J2248-511 with XMM-Newton. Previous X-ray observations showed a transition from a very soft state to a harder state five years later. We find that the…

We briefly review BeppoSAX observations of X-ray bright radio-galaxies. Their X-ray spectra are quite varied, and perhaps surprisingly, any similarity between radio-loud AGN and Seyfert galaxies is the exception rather than the rule. When…

We present a simple analytical formula for the Thomson depth of the X-ray heated skin of accretion disks valid at any radius and for a broad range of spectral indices of the incident X-rays, accretion rates and black hole masses. We expect…

The reflection spectrum produced by a cold medium illuminated by X-ray photons is not isotropic and its shape depends on the emission angle. In the reflection spectrum of an accretion disk of a black hole, the value of the emission angle…

We have observed a radio-quiet QSO Kaz 102 (z=0.136) with ASCA as a part of our program of complete spectral characterization of hard X-ray selected AGNs. We found that Kaz 102 shows unusual spectral properties. A simple power-law with…

We present models for reprocessing of an intense flux of X-rays and gamma rays expected in the vicinity of gamma ray burst sources. We consider the transfer and reprocessing of the energetic photons into observable features in the X-ray…