Astronomy and Astrophysics – Astrophysics – High Energy Astrophysical Phenomena
Scientific paper
2010-01-25
Astronomy and Astrophysics
Astrophysics
High Energy Astrophysical Phenomena
6 pages, 6 figures. Accepted for publication on PoS (contribution PoS(extremesky2009)031), proceedings of "The Extreme sky: Sa
Scientific paper
We present preliminary results on the variability properties of AGN above 20 keV in order to show the potential of the INTEGRAL IBIS/ISGRI and Swift/BAT instruments for hard X-ray timing analysis of AGN. The 15-50 keV light curves of 36 AGN observed by BAT during 5 years show significantly larger variations when the blazar population is considered (average normalized excess variance = 0.25) with respect to the Seyfert one (average normalized excess variance = 0.09). The hard X-ray luminosity is found to be anti-correlated to the variability amplitude in Seyfert galaxies and correlated to the black hole mass, confirming previous findings obtained with different AGN hard X-ray samples. We also present results on the Seyfert 1 galaxy IC 4329A, as an example of spectral variability study with INTEGRAL/ISGRI data. The position of the high-energy cut-off of this source is found to have varied during the INTEGRAL observations, pointing to a change of temperature of the Comptonising medium. For several bright Seyfert galaxies, a considerable amount of INTEGRAL data have already been accumulated and are publicly available, allowing detailed spectral variability studies at hard X-rays.
Beckmann Volker
Lubinski Piotr
Ponti Gabriele
Soldi Simona
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