Disk-Corona Models and X-Ray Emission from Seyfert Galaxies

Maraschi, L.; Haardt, Francesco

doi:10.1017/s0252921100042548

Cited by 9 publications

(4 citation statements)

References 30 publications

(36 reference statements)

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“…more than 99% significant) and has an equivalent width of ∼400 eV, higher but compatible within errors with reflection in the accretion disk. Addition of a reflection component having R=1 (where R is the solid angle in units of 2π subtended by the reflecting material (Maraschi & Haardt 1997)) does not improve the fit, probably due to the statistical quality of the data which is not sufficient to constrain this component. Similarly, the introduction of a cut-off to the power law (cutoffpl model in XSPEC) does not improve the quality of the fit but allows us to put a lower limit at E cut >70 keV.…”

Section: Ngc 6814mentioning

confidence: 99%

“…Modelling of high energy AGNs spectra has so far generally focussed on how to reproduce and explain the observed primary continuum shape. A good fraction of the proposed models ascribe the power law to the inverse Compton scattering of soft photons in a bath of "hot electrons" (see for example Maraschi & Haardt 1997). Variations to this baseline model depend on the energy distribution of these electrons and their location in relation to the accretion disc.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

INTEGRAL observations of active galactic nuclei obscured by the Galactic plane

Molina¹,

Malizia²,

Bassani³

et al. 2006

Monthly Notices of the Royal Astronomical Society

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In this paper, we present INTEGRAL observations of seven active galactic nuclei (AGNs): two newly discovered type 1 Seyferts, IGR J18027−1455 and J21247+5058 and five well‐known Seyferts, NGC 6814 (type 1.5), Cygnus A (type 2), MCG‐05‐23‐16 (type 2), ESO 103‐G035 (type 2) and GRS 1734‐292. For IGR J18027−1455 and J21247+5058, only INTEGRAL/IBIS data were available, while broad‐band spectra are presented and discussed for the remaining five sources for which either BeppoSAX or ASCA data were used in conjunction with INTEGRAL measurements. In the cases of NGC 6814 and GRS 1734‐292, data taken in different periods indicate variability in the flux: in the case of NGC 6814 by a factor of 16 over a period of about 10 years. Although limited in size, our sample can be used to investigate the parameter space of both the photon index and cut‐off energy. The mean photon index is 1.8, while the cut‐off energy ranges from 30–50 keV to greater than 200 keV; in the particular case of MCG‐05‐23‐16, ESO 103‐G035 and GRS 1734‐292, the cut‐off energy is well constrained at or below 100 keV. We have also tested an enlarged sample, which includes INTEGRAL data of three more AGNs, against the correlation found by a number of authors between the photon index and the cut‐off energy but have found no evidence for a relation between these two parameters. Our analysis indicates that there is a diversity in cut‐off energies in the primary continuum of Seyfert galaxies.

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Section: Ngc 6814mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

INTEGRAL observations of active galactic nuclei obscured by the Galactic plane

Molina¹,

Malizia²,

Bassani³

et al. 2006

Monthly Notices of the Royal Astronomical Society

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“…A good fraction of the proposed mod-els ascribe the power law to the inverse Compton scattering of soft photons in a bath of "hot electrons" (e.g. Maraschi & Haardt 1997;Zdziarski et al 1998). Variations to these basic models depend on the energy distribution of the electrons and their location in relation to the accretion disc.…”

Section: Introductionmentioning

confidence: 99%

The INTEGRAL Complete Sample of Type 1 AGN

Molina¹

2010

Proceedings of the Extreme Sky: Sampling the Universe Above 10 keV — PoS(extremesky2009)

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We present the broad-band X-ray characteristics of a complete sample of 36 type 1 AGN, detected by INTEGRAL in the 20-40 keV band above the 5.5 σ level. We performed the broad-band (1-110 keV) spectral analysis using INTEGRAL/Swift/BAT observations together with XMM-Newton, Chandra, ASCA and Swift/XRT data. We also present the general average properties of the sample, i.e. the distribution of photon indices, high energy cut-offs, reflection fractions and absorption properties, together with an in-depth analysis of their parameter space. We find that the average Seyfert 1 power law has an index of 1.7 with a dispersion of 0.2. The mean cut-off energy is at around 100 keV, with most objects displaying E c in the range 50-150 keV; the average amount of Compton reflection is 1.5 with a typical dispersion of 0.7. We do not find any convincing correlation between the various parameters, an indication that our analysis is not strongly dependent by the interplay between them. Finally, we investigate how the results presented in this work fit into current frameworks for AGN spectral modeling and Cosmic Diffuse X-ray Background synthesis models.

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“…It is likely, whether the accretion rate is high or low, that the gravitational energy liberated by this process is radiated locally with a large fraction in the form of thermal radiation from the surface of the disc, peaking in the optical/UV bands. A significant amount of these optical/UV photons are reprocessed by a) dust located beyond the sublimation radius and re-emitted in the infrared band (IR); and b) by a corona of hot electrons close to the accretion disc that up-scatters them via inverse Compton in the soft/hard X-ray bands where AGN emit a non negligible fraction of their luminosity (Maraschi and Haardt, 1997;Zdziarski, 1998).…”

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confidence: 99%

INTEGRAL view of AGN

Malizia,

Sazonov,

Bassani

et al. 2020

Preprint

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AGN are among the most energetic phenomena in the Universe and in the last two decades INTEGRAL's contribution in their study has had a significant impact. Thanks to the INTEGRAL extragalactic sky surveys, all classes of soft X-ray detected (in the 2-10 keV band) AGN have been observed at higher energies as well. Up to now, around 450 AGN have been catalogued and a conspicuous part of them are either objects observed at high-energies for the first time or newly discovered AGN. The high-energy domain (20-200 keV) represents an important window for spectral studies of AGN and it is also the most appropriate for AGN population studies, since it is almost unbiased against obscuration and therefore free of the limitations which affect surveys at other frequencies. Over the years, INTEGRAL data have allowed to characterise AGN spectra at high energies, to investigate their absorption properties, to test the AGN unification scheme and to perform population studies. In this review the main results are reported and INTEGRAL's contribution to AGN science is highlighted for each class of AGN. Finally, new perspectives are provided, connecting INTEGRAL's science with that at other wavelengths and in particular to the GeV/TeV regime which is still poorly explored.

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Disk-Corona Models and X-Ray Emission from Seyfert Galaxies

Cited by 9 publications

References 30 publications

INTEGRAL observations of active galactic nuclei obscured by the Galactic plane

INTEGRAL observations of active galactic nuclei obscured by the Galactic plane

The INTEGRAL Complete Sample of Type 1 AGN

INTEGRAL view of AGN

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