相关论文: Warm absorbers in active galactic nuclei

Understanding the thermal equilibrium (stability) curve may offer insights into the nature of the warm absorbers often found in active galactic nuclei. Its shape is determined by factors like the spectrum of the ionizing continuum and the…

We present the analysis of 900 ks high-resolution RGS XMM-Newton observations of the nearby Seyfert galaxy Mrk 509 with the use of a self-consistent warm absorber (WA) model. We perform a physically motivated approach to the modeling of WA…

A new modeling way of describing the continuous absorption of electromagnetic (EM) radiation in dense partially ionized hydrogen plasma is tested in this work. It is shown that the obtained results give a possibility of calculating spectral…

Here we present the results of a Suzaku observation of the Broad Line Radio Galaxy 3C 445. We confirm the results obtained with the previous X-ray observations which unveiled the presence of several soft X-ray emission lines and an overall…

We present detailed evidence for a warm absorber in the Seyfert 1 galaxy MCG--6-30-15 and dispute earlier claims for relativistic O line emission. The HETG spectra show numerous narrow, unresolved (FWHM < 200 km/s) absorption lines from a…

We use hard X-ray data for an "optimal" sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local Universe. Of all Seyfert 2 galaxies in the sample, 75% are…

Recent Chandra and XMM observations of distant quasars have shown strong local (z~0) X-ray absorption lines from highly ionized gas, primarily He-like oxygen. The nature of these X-ray absorbers, i.e., whether they are part of the hot gas…

We study the column densities of neutral atomic, molecular, and warm ionized Galactic gas through their continuous absorption of extragalactic X-ray spectra at |b| > 25 degrees. For N(H,21cm) < 5x10^20 cm^-2 there is an extremely tight…

We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and Nov. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating…

We present the results of a uniform analysis of the soft X-ray spectra of fifteen type I AGN observed with the high resolution X-ray gratings on board \emph{Chandra}. We found that ten of the fifteen AGN exhibit signatures of an intrinsic…

A hydromagnetic (MHD) wind from a clumpy molecular accretion disk is invoked to explain observations of warm absorbing (WA) gas in UVX from Sy galaxies. This paper focuses on two issues: (1) compatibility of kinematics and dynamics of MHD…

We have developed a new X-ray absorption model, called {\tt IONeq}, which computes the optical depth $\tau(E)$ simultaneously for ions of all abundant elements, assuming ionization equilibrium and taking into account turbulent broadening.…

(Abridged) We present a two month Suzaku X-ray monitoring of the Seyfert 1 galaxy NGC 5548. The campaign consists of 7 observations. We analyze the response in the opacity of the gas that forms the ionized absorber to ionizing flux…

We analyze relative abundances and ionization conditions in a strong absorption system at z=6.84, seen in the spectrum of the z=7.54 background quasar ULAS J134208.10+092838.61. Singly ionized C, Si, Fe, Mg, and Al measurements are…

We present maps of the Galactic X-ray Halo and constrain the location of X-ray absorbing gas using the X-ray radiation transfer as distance a indicator. Based on a consistent model of the soft X-ray background (SXRB) and the ROSAT all-sky…

We present XMM-Newton observations of the Seyfert 1 AGN H0557-385. We have conducted a study into the warm absorber present in this source, and using high-resolution RGS data we find that the absorption can be characterised by two phases: a…

The UV to X-ray continuum of active galactic nuclei (AGN) is important for maintaining the ionisation and thermal balance of the warm absorbers (WAs). However, the spectra in the sensitive energy range $\sim \,13.6 -300 \ev$ are…

We have surveyed the optical linear polarization of a completely identified sample of 43 bright soft-X-ray-selected ROSAT AGN. Most (40) of these AGN show low polarization (<1%), and no clear optical reddening. This supports the suggestion…

Although soft X-ray absorption features in AGN were discovered almost ten years ago, the nature and location of the gas creating them has remained controversial. Guided by the results of recent high-resolution X-ray spectroscopy, we argue…

We report on the long- and short-term X-ray spectral analysis of the polar-scattered Seyfert 1.2 galaxy ESO 323-G77, observed in three epochs between 2006 and 2013 with Chandra and XMM-Newton. Four high-resolution Chandra observations give…