Clumpy accretion flows in active galactic nuclei: X-ray variability and spectral properties

2010 ◽  
Author(s):  
W. Ishibashi ◽  
T. J.-L. Courvoisier ◽  
A. Comastri ◽  
L. Angelini ◽  
M. Cappi
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
X Ray ◽  
Accretion Flows

scholarly journals OPTICAL SPECTRAL PROPERTIES OFSWIFTBURST ALERT TELESCOPE HARD X-RAY-SELECTED ACTIVE GALACTIC NUCLEI SOURCES

2010 ◽  
Vol 710 (1) ◽  
pp. 503-539 ◽  
Author(s):  
Lisa M. Winter ◽  
Karen T. Lewis ◽  
Michael Koss ◽  
Sylvain Veilleux ◽  
Brian Keeney ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
X Ray

scholarly journals The X-ray emission in young radio active galactic nuclei

2020 ◽  
Vol 497 (1) ◽  
pp. 482-497
Author(s):  
Mai Liao ◽  
Minfeng Gu ◽  
Minhua Zhou ◽  
Liang Chen
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Strongly Correlated ◽  
Strong Correlations ◽  
X Ray ◽  
Accretion Flows ◽  
Combining Data ◽  
Vlbi Data ◽  
5 Ghz

ABSTRACT In this work, we investigated the X-ray emission for a sample of young radio active galactic nuclei (AGNs) by combining data from Chandra/XMM–Newton with data for other wavebands. We find strong correlations between the X-ray luminosity LX at 2–10 keV and the radio luminosities LR at 5 GHz for the VLBI radio-core, VLA radio-core and Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) component, indicating that both parsec- and kiloparsec-scale radio emissions are strongly correlated with X-ray emission in these sources. We find an approximately linear dependence of the radio on the X-ray luminosity in the sources with radiatively efficient accretion flows (i.e. the Eddington ratio Redd ≳ 10−3), with b ∼ 1 ($L_{\rm R}\, \propto \, L_{\rm X} ^{b}$) and $\xi _{\rm RX}\, \sim$ 1 in the fundamental plane using the VLBI data. The dependence is consistent with the re-analysed results of a previous study of Fan and Bai at Redd ≳ 10−3, but is significantly different from the theoretical prediction of accretion flow as the origin of X-ray emission. In contrast to the case for radio-quiet quasars, there is no significant correlation between Γ and the Eddington ratio. Our results seem to indicate that the X-ray emission of high-accretion young radio AGNs may be from the jet. We constructed the spectral energy distributions (SEDs) for 18 sources (most of which are in radiatively efficient accretion), namely nine galaxies and nine quasars with high-quality X-ray data, and find that the X-ray emission of most quasars is more luminous than that of normal radio-quiet quasars. This is clearly seen from the quasar composite SED, in which the X-ray emission is apparently higher than that of radio-quiet quasars, probably supporting jet-related X-ray emission in young radio AGNs. The possibility that the X-ray emission is from self-synchrotron Compton is discussed.

scholarly journals The X‐Ray Spectral Properties and Variability of Luminous High‐Redshift Active Galactic Nuclei

2005 ◽  
Vol 630 (2) ◽  
pp. 729-739 ◽  
Author(s):  
O. Shemmer ◽  
W. N. Brandt ◽  
C. Vignali ◽  
D. P. Schneider ◽  
X. Fan ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
High Redshift ◽  
Galactic Nuclei ◽  
X Ray

scholarly journals ROSAT Observations of Active Galactic Nuclei

1994 ◽  
Vol 159 ◽  
pp. 53-62 ◽  
Author(s):  
W. Brinkmann
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
High Sensitivity ◽  
Good Energy Resolution ◽  
Ongoing Research ◽  
X Ray ◽  
Sky Survey ◽  
Good Energy ◽  
First Time

The large number of Active Galactive Nuclei detected for the first time through their X-ray emission in the ROSAT All Sky Survey as well as the first measurements of the X-ray emission of many previously known AGN provide a new unprecedented large basis for the statistical and morphological exploration of these objects.The soft energy range of the X-Ray Telescope, the good energy resolution of the PSPC detector, and the high sensitivity of the instrument further allows an investigation of the spectral properties of sources in this energetically important energy band.A short overview is given of the actual ongoing research concentrating on the study of the soft X-ray class properties of the various types of AGN.

scholarly journals The OPTX Project: Comparing the Optical and X-Ray Spectral Properties of Active Galactic Nuclei

2009 ◽  
Vol 5 (S267) ◽  
pp. 142-142
Author(s):  
Laura Trouille ◽  
Amy Barger
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Classification Scheme ◽  
Galactic Nuclei ◽  
Complete Sample ◽  
X Ray ◽  
Central Engine

AbstractUsing a uniformly selected and highly spectroscopically complete sample of Chandra X-ray sources, we show that one cannot use X-ray spectral classifications and optical spectral classifications equivalently. Until a better understanding is reached for how the X-ray and optical classifications relate to the obscuration of the central engine, the use of a mixed classification scheme can only complicate the interpretation of X-ray AGN samples.

A negative correlation between RUV and αox in low-luminosity AGNs

2018 ◽  
Vol 14 (S342) ◽  
pp. 248-249
Author(s):  
Shuang-Liang Li
Keyword(s):  
Active Galactic Nuclei ◽  
Negative Correlation ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Strong Negative Correlation ◽  
X Ray ◽  
Accretion Flow ◽  
Accretion Flows ◽  
Viscosity Parameter ◽  
First Time

AbstractIt has been controversial for years that the accretion mode is different for bright active galactic nuclei (AGNs) and low-luminosity AGNs (LLAGNs). In this work, we compile from literature a sample of 32 LLAGNs, consisting 18 LINERs and 14 low Eddington ratio (λ) Seyfert galaxies. A strong negative correlation between the radio loudness RUV and the optical to X-ray spectral index αox is reported for the first time. We further demonstrate that this negative correlation can be understood consistently and comprehensively under the truncated accretion — jet model, a model that has been applied successfully to LLAGNs. We argue that the scatter in the observations is mainly due to the spread in the viscosity parameter α of a hot accretion flow, a parameter that can potentially serve as a diagnosis of the strength and/or configuration of magnetic fields in accretion flows.

scholarly journals 5. Atmospheres of Accretion Discs

1985 ◽  
Vol 19 (1) ◽  
pp. 515-519
Author(s):  
James E. Pringle
Keyword(s):  
Active Galactic Nuclei ◽  
Strong Interaction ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
High Energy ◽  
Observational Evidence ◽  
Accretion Discs ◽  
Theoretical Modelling ◽  
X Ray ◽  
Actual Observation

Accretion discs are a popular ingredient among theorists for modelling a number of high energy astronomical objects like quasars, active galactic nuclei (Rees 1984) and galactic X-ray sources (Levin and van der Heuvel 1983). However, the observational evidence (as opposed to the strong theoretical presumption) that accretion discs exist in these objects is weak, and in only one case has some attempt been made to argue the case for a disc on the basis of its spectral properties (Malkan 1983). Indeed the structure of accretion discs is sufficiently ill-understood that any progress in this area must rest on a strong interaction between theoretical modelling and the actual observation of accretion discs in action.

scholarly journals X-ray spectral properties of active galactic nuclei in the Chandra Deep Field South

2006 ◽  
Vol 451 (2) ◽  
pp. 457-474 ◽  
Author(s):  
P. Tozzi ◽  
R. Gilli ◽  
V. Mainieri ◽  
C. Norman ◽  
G. Risaliti ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
X Ray

scholarly journals The XMM‐Newton Wide‐Field Survey in the COSMOS Field. IV. X‐Ray Spectral Properties of Active Galactic Nuclei

2007 ◽  
Vol 172 (1) ◽  
pp. 368-382 ◽  
Author(s):  
V. Mainieri ◽  
G. Hasinger ◽  
N. Cappelluti ◽  
M. Brusa ◽  
H. Brunner ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Field Survey ◽  
Galactic Nuclei ◽  
Wide Field ◽  
X Ray
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