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Title: THE INTEGRAL HIGH-ENERGY CUT-OFF DISTRIBUTION OF TYPE 1 ACTIVE GALACTIC NUCLEI

In this Letter we present the primary continuum parameters, the photon index Γ, and the high-energy cut-off E {sub c} of 41 type-1 Seyfert galaxies extracted from the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) complete sample of active galactic nuclei (AGNs). We performed broadband (0.3-100 keV) spectral analysis by simultaneously fitting the soft and hard X-ray spectra obtained by XMM and INTEGRAL/IBIS-Swift/BAT, respectively, in order to investigate the general properties of these parameters, in particular their distribution and mean values. We find a mean photon index of 1.73 with a standard deviation of 0.17 and a mean high-energy cut-off of 128 keV with a standard deviation of 46 keV for the whole sample. This is the first time that the cut-off energy is constrained in such a large number of AGNs. We have 26 measurements of the cut-off, which corresponds to 63% of the entire sample, distributed between 50 and 200 keV. There are a further 11 lower limits mostly below 300 keV. Using the main parameters of the primary continuum, we have been able to obtain the actual physical parameters of the Comptonizing region, i.e., the plasma temperature kT {sub e} from 20 to 100 keV and the optical depth τ < 4. Finally, with themore » high signal-to-noise ratio spectra starting to come from NuSTAR it will soon be possible to better constrain the cut-off values in many AGNs, allowing the determination of more physical models and thus better understand the continuum emission and geometry of the region surrounding black holes.« less
Authors:
; ; ;  [1] ; ;  [2] ;  [3]
  1. IASF-Bologna, INAF, Via Gobetti 101, I-40129 Bologna (Italy)
  2. IAPS-Roma, INAF, Via Fosso del Cavaliere 100, I-00133 Roma (Italy)
  3. School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)
Publication Date:
OSTI Identifier:
22363977
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 782; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BLACK HOLES; ELECTRON TEMPERATURE; GALAXY NUCLEI; GAMMA RADIATION; HARD X RADIATION; INDEXES; ION TEMPERATURE; KEV RANGE; PHOTON EMISSION; PHOTONS; SEYFERT GALAXIES; SIGNAL-TO-NOISE RATIO; X-RAY GALAXIES