scholarly journals The WISSH quasars project

2020 ◽  
Vol 635 ◽  
pp. L5 ◽  
Author(s):  
L. Zappacosta ◽  
E. Piconcelli ◽  
M. Giustini ◽  
G. Vietri ◽  
F. Duras ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Accretion Disc ◽  
Broad Line ◽  
Absorption Column ◽  
Mid Infrared ◽  
X Ray ◽  
Similar Dependence ◽  
Photon Index ◽  
Nuclear Regions

Hyper-luminous quasars (Lbol ≳ 1047 erg s−1) are ideal laboratories to study the interaction and impact of the extreme radiative field and the most powerful winds in the active galactic nuclei (AGN) nuclear regions. They typically exhibit low coronal X-ray luminosity (LX) compared to the ultraviolet (UV) and mid-infrared (MIR) radiative outputs (LUV and LUV); a non-negligible fraction of them report even ∼1 dex weaker LX compared to the prediction of the well established LX–LUV and LX–LUV relations followed by the bulk of the AGN population. In our WISE/SDSS-selected Hyper-luminous (WISSH) z = 2 − 4 broad-line quasar sample, we report on the discovery of a dependence between the intrinsic 2–10 keV luminosity (L2 − 10) and the blueshifted velocity of the CIV emission line (vCIV) that is indicative of accretion disc winds. In particular, sources with the fastest winds (vCIV ≳ 3000 km s−1) possess ∼0.5–1 dex lower L2 − 10 than sources with negligible vCIV. No similar dependence is found on LUV, LUV, Lbol, the photon index, or the absorption column density. We interpret these findings in the context of accretion disc wind models. Both magnetohydrodynamic and line-driven models can qualitatively explain the reported relations as a consequence of X-ray shielding from the inner wind regions. In case of line-driven winds, the launch of fast winds is favoured by a reduced X-ray emission, and we speculate that these winds may play a role in directly limiting the coronal hard X-ray production.

scholarly journals Correlation between relativistic reflection fraction and photon index in NuSTAR sample of Seyfert 1 AGN

2020 ◽  
Vol 495 (3) ◽  
pp. 3373-3386
Author(s):  
Savithri H Ezhikode ◽  
Gulab C Dewangan ◽  
Ranjeev Misra ◽  
Ninan Sajeeth Philip
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Relativistic Effects ◽  
Accretion Disc ◽  
Telescope Array ◽  
X Ray ◽  
Photon Index ◽  
The Relationship ◽  
Reflection Component

ABSTRACT The primary X-ray emission from active galactic nuclei (AGNs), described by a power-law, irradiates the accretion disc producing reflection features in the spectrum. The reflection features arising from the inner regions of the disc can be significantly modified by the relativistic effects near the black hole. We investigate the relationship between the relativistic reflection fraction Rf, defined as the ratio of the coronal intensity that illuminates the accretion disc to the coronal intensity observed directly, and the hard X-ray photon index Γ of a Nuclear Spectroscopic Telescope Array (NuSTAR) sample of Seyfert 1 galaxies. The X-ray spectra are modelled using relxill code that helps to directly obtain the reflection fraction of a relativistically smeared reflection component. The parameter Rf depends on the amount of Comptonized X-ray emission intercepted by the inner accretion disc. We found a positive correlation between Γ and Rf in our sample. Seed photons from a larger area of an accretion disc entering the corona will result in increased cooling of the coronal plasma, giving rise to steeper X-ray spectrum. The corona irradiating the larger area of the disc will result in higher reflection fraction. Thus, the observed Rf –Γ relation is most likely related to the variations in the disc–corona geometry of AGNs.

scholarly journals Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation

2014 ◽  
Vol 447 (2) ◽  
pp. 1692-1704 ◽  
Author(s):  
Qi-Xiang Yang ◽  
Fu-Guo Xie ◽  
Feng Yuan ◽  
Andrzej A. Zdziarski ◽  
Marek Gierliński ◽  
...  
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
Photon Index ◽  
X Ray Binaries

scholarly journals Mid‐Infrared Properties and Color Selection for X‐Ray‐Detected Active Galactic Nuclei in the MUSYC Extended Chandra Deep Field–South

2008 ◽  
Vol 680 (1) ◽  
pp. 130-142 ◽  
Author(s):  
Carolin N. Cardamone ◽  
C. Megan Urry ◽  
Maaike Damen ◽  
Pieter van Dokkum ◽  
Ezequiel Treister ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Mid Infrared ◽  
X Ray ◽  
Color Selection ◽  
Selection For

scholarly journals The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation

2015 ◽  
Vol 454 (1) ◽  
pp. 766-803 ◽  
Author(s):  
D. Asmus ◽  
P. Gandhi ◽  
S. F. Hönig ◽  
A. Smette ◽  
W. J. Duschl
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Mid Infrared ◽  
X Ray

scholarly journals A MULTI-WAVELENGTH STUDY OF LOW-REDSHIFT CLUSTERS OF GALAXIES. I. COMPARISON OF X-RAY AND MID-INFRARED SELECTED ACTIVE GALACTIC NUCLEI

2011 ◽  
Vol 729 (1) ◽  
pp. 22 ◽  
Author(s):  
David W. Atlee ◽  
Paul Martini ◽  
Roberto J. Assef ◽  
Daniel D. Kelson ◽  
John S. Mulchaey
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Clusters Of Galaxies ◽  
Mid Infrared ◽  
X Ray ◽  
Multi Wavelength

scholarly journals X-ray spectral and eclipsing model of the clumpy obscurer in active galactic nuclei

2019 ◽  
Vol 629 ◽  
pp. A16 ◽  
Author(s):  
Johannes Buchner ◽  
Murray Brightman ◽  
Kirpal Nandra ◽  
Robert Nikutta ◽  
Franz E. Bauer
Keyword(s):  
Active Galactic Nuclei ◽  
Column Density ◽  
Galactic Nuclei ◽  
Line Of Sight ◽  
Broad Line ◽  
X Ray ◽  
Line Region ◽  
Self Consistent ◽  
Multi Wavelength ◽  
Table Model

We present a unification model for a clumpy obscurer in active galactic nuclei (AGN) and investigate the properties of the resulting X-ray spectrum. Our model is constructed to reproduce the column density distribution of the AGN population and cloud eclipse events in terms of their angular sizes and frequency. We developed and released a generalised Monte Carlo X-ray radiative transfer code, XARS, to compute X-ray spectra of obscurer models. The geometry results in strong Compton scattering, causing soft photons to escape also along Compton-thick sight lines. This makes our model spectra very similar to our TORUS previous model. However, only if we introduce an additional Compton-thick reflector near the corona, we achieve good fits to NuSTAR spectra. This additional component in our model can be interpreted as part of the dust-free broad-line region, an inner wall or rim, or a warped disk. It cannot be attributed to a simple disk because the reflector must simultaneously block the line of sight to the corona and reflect its radiation. We release our model as an Xspec table model and present corresponding CLUMPY infrared spectra, paving the way for self-consistent multi-wavelength analyses.

scholarly journals The relationship between X-ray and optical absorbers in active galactic nuclei

2020 ◽  
Vol 493 (1) ◽  
pp. 930-939 ◽  
Author(s):  
Gunnar W Jaffarian ◽  
C Martin Gaskell
Keyword(s):  
Active Galactic Nuclei ◽  
Column Density ◽  
Scattered Light ◽  
Galactic Nuclei ◽  
Broad Line ◽  
Large Scatter ◽  
Standard Type ◽  
X Ray

ABSTRACT We present a large compilation of reddening estimates from broad-line Balmer decrements for active galactic nuclei (AGNs) with measured X-ray column densities. The median reddening is E(B − V) ≈ 0.77 ± 0.10 for type-1 to type-1.9 AGNs with reported column densities. This is notably higher than the median reddening of AGNs from the SDSS. We attribute this to the selection bias of the SDSS towards blue AGNs. For other AGNs, we find evidence of a publication bias against reporting low column densities. We find a significant correlation between NH and E(B − V) but with a large scatter of ±1 dex. On average, the X-ray columns are consistent with those predicted from E(B − V) for a solar neighbourhood dust-to-gas ratio. We argue that the large scatter of column densities and reddenings can be explained by X-ray column density variability. For AGNs with detectable broad-line regions (BLRs) that have undergone significant changes of Seyfert type (‘changing-look’ AGNs), we do not find any statistically significant differences in NH or E(B − V) compared to standard type-1 to type-1.9 AGNs. There is no evidence for any type-1 AGNs being Compton thick. We also analyse type-2 AGNs and find no significant correlation between NH and narrow-line region reddening. We find no evidence for a previously claimed anticorrelation. The median column density of LINERs is 22.68 ± 0.75 compared to a column density of 22.90 ± 0.28 for type-2 AGNs. We find the majority of low column density type-2 AGNs are LINERs, but NH is probably underestimated because of scattered light.

scholarly journals The role of failed accretion disk winds in active galactic nuclei

2019 ◽  
Vol 15 (S356) ◽  
pp. 82-86 ◽  
Author(s):  
Margherita Giustini ◽  
Daniel Proga
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
Broad Line ◽  
X Ray ◽  
Broad Line Region ◽  
Line Region ◽  
Gravitational Pull ◽  
Theoretical Evidence

AbstractBoth observational and theoretical evidence point at outflows originating from accretion disks as fundamental ingredients of active galactic nuclei (AGN). These outflows can have more than one component, for example an unbound supersonic wind and a failed wind (FW). The latter is a prediction of the simulations of radiation-driven disk outflows which show that the former is accompanied by an inner failed component, where the flow struggles to escape from the strong gravitational pull of the supermassive black hole. This FW component could provide a physical framework to interpret various phenomenological components of AGN. Here we briefly discuss a few of them: the broad line region, the X-ray obscurer, and the X-ray corona.

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