Related papers: Warm absorbers in active galactic nuclei
Observations of warm absorbers provided new ways to study the nuclear environments of AGNs. I discuss basic properties of warm absorbers and early developments with ROSAT, ASCA and HST observations. I briefly touch upon recent advances made…
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. However, by making use of the newly-available high-resolution spectra provided…
The narrow-line Seyfert 1 galaxy I Zwicky 1 shows a unique and complex system of ionised gas in outflow, which consists of an ultra-fast wind and a two-component warm absorber. In the last two decades, XMM-Newton monitored the source…
Recent modeling of the warm absorber in active galactic nuclei has proved the usefulness of constant total (gas plus radiation) pressure models, which are highly stratified in temperature and density. We explore the consistency of those…
In accordance with the AGN Unified Model, observed polarization can be related to the orientation of the line of sight with respect to the torus. AGN X-ray emission arises from the central region and carries the imprints of the obscuring…
We present a study of the intrinsic absorption lines in the ultraviolet spectra of Seyfert 1 galaxies. We find that the fraction of Seyfert 1 galaxies that show absorption associated with their active nuclei is more than one-half (10/17),…
Aims. We examine the high energy resolution X-ray spectrum of the narrow-line Seyfert 1 galaxy Mrk 766 using 4 observations taken with XMM-Newton in 2005, to investigate the properties of the complex ionised absorber / emitter along the…
We analyze the high-resolution X-ray spectrum of the Seyfert 1 galaxy NGC 5548, for the full 0.1-10 keV band, using improved calibration results of the Chandra-LETGS instrument. The warm absorber consists of at least three ionization…
The Seyfert 1 galaxy Mrk 279 was observed by XMM-Newton in November 2005 in three consecutive orbits, showing significant short-scale variability (average soft band variation in flux ~20%). The source is known to host a two-component warm…
The absorption lines in the soft X-ray spectrum of MCG--6-30-15 are studied using the Reflection Grating Spectrometer data from the 2001 XMM-Newton 320 ks observation. A line search of the full time-averaged spectrum reveals 51 absorption…
We present a XMM-Newton observation of Markarian 304, a Seyfert 1 galaxy at z = 0.066. The EPIC data show that MKN 304 is affected by heavy (Nh ~10^{23} cm{-2}) obscuration due to ionized gas. A two-phase warm absorber provides an adequate…
A recent observation of the nearby (z=0.042) narrow-line Seyfert 1 galaxy RE J1034+396 on 2007 May 31 showed strong quasi-periodic oscillations (QPOs) in the 0.3-10 keV X-ray flux. We present phase-resolved spectroscopy of this observation,…
High resolution spectroscopic observations of Seyfert galaxies with Chandra and XMM-Newton allows us to study the detailed ionization and thermal structures of the X-ray absorbing/emitting material in the circumnuclear environment. The vast…
Recent high-resolution measurements suggest that the soft X-ray spectrum of obscured Radio Galaxies (RG) exhibits signatures of photoionised gas (e.g. 3C 445 and 3C 33) similar to those observed in radio-quiet obscured Active Galactic…
We detect seven distinct absorbing systems in the high-resolution X-ray spectrum of the Seyfert 1 galaxy IC 4329A, taken with XMM-Newton. Firstly we detect absorption due to cold gas in our own Galaxy and warm gas in the Galactic halo or…
We investigate the origin of the broad absorption features detected near 1-1.4 keV in several Narrow Line Seyfert 1 galaxies, by modelling the absorbing medium with various physical parameters, using the ionization code PEGAS. The observed…
When an AGN is obscured, the warm reflecting gas nearby can be seen by a combination of bremsstrahlung, intrinsic line emission, and reflection of the nuclear continuum, both by electron scattering and by resonance line scattering.…
Warm absorbers and related phenomena are one of the observable manifestations of outflows or winds from active galactic nuclei (AGN). Warm absorbers are common in low luminosity AGN, they have been extensively studied observationally, and…
We obtained X-ray spectra of the Seyfert 1 galaxy NGC~3516 in March 1995 using ASCA. Simultaneous far-UV observations were obtained with HUT on the Astro-2 shuttle mission. The ASCA spectrum shows a lightly absorbed power law of energy…
In this paper we explore collisional ionization and time-evolving photoionization in the, X-ray discovered, ionized absorbers in Seyfert galaxies. These absorbers show temporal changes inconsistent with simple equilibrium models. We develop…