Related papers: Synthetic absorption lines for a clumpy medium: a …
We review the main results from axisymmetric, time-dependent hydrodynamical simulations of radiation driven disk winds in AGN. We illustrate the capability of such simulations to provide useful insights into the three domains of…
We perform multi-dimensional radiative transfer simulations to compute spectra for a hydrodynamical simulation of a line-driven accretion disk wind from an active galactic nucleus. The synthetic spectra confirm expectations from…
Many studies have considered the roles of clouds, outflows, and turbulence in producing the broad emission and absorption lines in the spectra of active galactic nuclei (AGNs). However, these are often treated as separate or even competing…
We explore the effective UV-optical albedos of a variety of types of broad emission line clouds, as well as their possible effects on the observed spectra of AGN. An important albedo source in moderately ionized ionization-bounded clouds is…
Strong absorption lines are common in rest-frame UV spectra of AGNs due to a variety of resonant transitions, for example the HI Lyman series lines (most notably Ly-alpha 1216) and high-ionization doublets like CIV 1549,1551. The lines are…
The 2-10 keV continuum of AGN is generally well represented by a single power law. However, at smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the ''soft X-ray excess''. Until…
Multi-wavelength spectroscopy of NGC 5548 revealed remarkable changes due to presence of an obscuring wind from the accretion disk. This broadened our understanding of obscuration and outflows in AGN. Swift monitoring of NGC 5548 shows that…
We present a systematic investigation of X-ray spectral variability of Seyfert 1 galaxies using a ``spectral-ratio model fitting'' technique, which we developed to estimate contribution of the putative clumpy absorbers to the spectral…
More than half of all low-redshift AGN exhibit UV and X-ray absorption by highly ionized gas. The observed UV and X-ray absorption lines are almost always blue-shifted at velocities of hundreds of km/s, indicating that the absorbing gas is…
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…
UltraFast Outflows (UFO) are observed in some active galactic nuclei (AGN), with blueshifted and highly ionised Fe-K absorption features. AGN typically have a UV bright accretion flow, so UV line driving is an obvious candidate for…
Warm absorbers are present in many Active Galactic Nuclei (AGN), seen as mildly ionised gas outflowing with velocities of a few hundred to a few thousand kilometres per second. These slow velocities imply a large launch radius, pointing to…
"Changing look" Active Galactic Nuclei (AGN) are a subset of Seyfert galaxies characterized by rapid transitions between Compton-thin and Compton-thick regimes. In their Compton-thin state, the central engine is less obscured, hence…
We present a method that allows us to estimate the distance from the continuum source located in the center of AGN to the highly ionized gas called warm absorber. We compute a set of constant total pressure photoionization models compatible…
The typical optical-UV continuum slopes observed in many type 1 AGN are redder than expected from thin accretion disk models. A possible resolution to this conundrum is that many AGN are reddened by dust along the line of sight. To explore…
The Absorption Measure Distribution (AMD) in the X-ray outflows of Seyfert active galactic nuclei (AGN) describes the distribution of absorbing column density as a function of ionization parameter. Up to now, AMD has been measured only for…
We present new interpretation of Ton S180 spectrum obtained by {\it Chandra} Spectrometer (Low Energy Transmission Grating). Several narrow absorption lines and a few emission disk lines have been successfully fitted to the data. We have…
Recent radiation-magnetohydrodynamic simulations of active galactic nuclei predict the presence of the disk winds, which may get unstable and turn into fragmented clumps far from the central black hole. These inner winds and the outer…
Galactic winds probe how feedback regulates the mass and metallicity of galaxies. Galactic winds have cold gas, which is mainly observable with absorption and emission lines. Theoretically studying how absorption lines are produced requires…
Observations of the circumgalactic medium (CGM) often display coincident absorption from species with widely varying ionization states, providing direct evidence for complex, multiphase interactions. Motivated by these measurements, we…