Related papers: Unobscured Type 2 AGNs
Variability detected in galaxies is usually attributed to their active galactic nuclei (AGNs). While all AGNs are intrinsically variable, the AGN unification model predicts that type~2 AGNs rarely vary because their engines are blocked by…
The Two Micron All Sky Survey (2MASS) is finding previously unidentified, luminous red active galactic nuclei (AGN). This new sample has a space density similar to, or greater than, previously known AGN, suggesting that a large fraction of…
In this work we present the most comprehensive INTEGRAL AGN sample which lists 272 objects. Here we mainly use this sample to study the absorption properties of active galaxies, to probe new AGN classes and to test the AGN unification…
(Abridged) Since its launch in October 2002, the INTEGRAL satellite has revolutionized our knowledge of the hard X-ray sky thanks to its unprecedented imaging capabilities and source detection positional accuracy above 20 keV. Nevertheless,…
XMM-Newton spectra of five red, 2MASS AGN, selected from a sample observed by Chandra to be relatively X-ray bright and to cover a range of hardness ratios, confirm the presence of substantial absorbing material in three sources with…
Active galactic nuclei (AGN) are known to be variable sources across the entire electromagnetic spectrum, in particular at optical/ultraviolet and X-ray energies. Over the past decades, a growing number of AGN have displayed type…
Above $\sim$3 keV, the X-ray spectrum of the active galactic nuclei (AGN) is characterized by the intrinsic continuum and compton reflection features. For type-1 AGN, several regions could contribute to the reflection. In order to…
[Abridged] We present ISO far-infrared (IR) observations of 21 hard X-ray selected AGN from the HEAO-1 A2 sample. We compare the far-IR to X-ray spectral energy distributions (SEDs) of this sample with various radio and optically selected…
The results of a 0.4-10.0 keV ASCA spectral analysis of a sample of low-luminosity AGN (LLAGN; M51, NGC 3147, NGC 4258), low-ionization nuclear emission line regions (LINERs; NGC 3079, NGC 3310, NGC 3998, NGC 4579, NGC 4594) and starburst…
We have conducted a series of investigations on the geometry of the reddening material in AGNs, which have important implications to the AGN unification and SMBH demography. According to our statistics of partially obscured quasars, we…
(Abridged) We analyzed the {\it Chandra} and {\it XMM-Newton} archival observations for 72 type 2 quasars at $z<1$. These objects were was selected based on the [O III]$\lambda$5007 optical emission line which we assume to be an approximate…
Recent Chandra and XMM-Newton surveys have uncovered a large fraction of the obscured AGN responsible of the hard X-ray background. One of the most intriguing results of extensive programs of follow-up observations concerns the optical and…
We present the result of a spectroscopic campaign targeting Active Galactic Nucleus (AGN) candidates selected using a novel unsupervised machine-learning (ML) algorithm trained on optical and mid-infrared (mid-IR) photometry. AGN candidates…
We present Chandra and optical observations of a candidate dual AGN discovered serendipitously while searching for recoiling black holes via a cross-correlation between the serendipitous XMM source catalog (2XMMi) and SDSS-DR7 galaxies with…
We used Transiting Exoplanet Survey Satellite (TESS) data to identify 29 candidate active galactic nuclei (AGNs) through their optical variability. The high-cadence, high-precision TESS light curves present a unique opportunity for the…
We observed 7 INTEGRAL sources with the Chandra X-ray Observatory to refine their localization to ~2 arcsec and to study their X-ray spectra. Two sources are inferred to have a Galactic origin: IGR J08390-4833 is most likely a magnetic…
From detailed spectral analysis of a large sample of low-redshift active galactic nuclei (AGNs) selected from the Sloan Digital Sky Survey, we demonstrate---statistically for the first time---that narrow optical Fe II emission lines, both…
Over ten mid-infrared (mid-IR) and X-ray models are currently attempting to describe the nuclear obscuring material of active galactic nuclei (AGNs), but many questions remain unresolved. This study aims to determine the physical parameters…
From extensive radiative transfer calculations we find that clumpy torus models with \No \about 5--15 dusty clouds along radial equatorial rays successfully explain AGN infrared observations. The dust has standard Galactic composition, with…
X-ray spectroscopy of heavily obscured Active Galactic Nuclei (AGN) offers a unique opportunity to study the circum-nuclear environment of accreting supermassive black holes (SMBHs). However, individual models describing the obscurer have…