NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-19 T15:51:18 PDT
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For refcode 2007A&A...475..827B:
Retrieve 44 NED objects in this reference.
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NED Abstract

Copyright by European Southern Observatory (ESO). Reproduced by permission
2007A&A...475..827B Hard X-ray variability of active galactic nuclei Beckmann, V.; Barthelmy, S. D.; Courvoisier, T. J.-L.; Gehrels, N.; Soldi, S.; Tueller, J.; Wendt, G. Abstract. Aims. Active Galactic Nuclei are known to be variable throughout the electromagnetic spectrum. An energy domain poorly studied in this respect is the hard X-ray range above 20 keV. Methods: The first 9 months of the Swift/BAT all-sky survey are used to study the 14-195 keV variability of the 44 brightest AGN. The sources have been selected due to their detection significance of >10 {sigma}. We tested the variability using a maximum likelihood estimator and by analysing the structure function. Results: Probing different time scales, it appears that the absorbed AGN are more variable than the unabsorbed ones. The same applies for the comparison of Seyfert 2 and Seyfert 1 objects. As expected the blazars show stronger variability. 15% of the non-blazar AGN show variability of >20% compared to the average flux on time scales of 20 days, and 30% show at least 10% flux variation. All the non-blazar AGN which show strong variability are low-luminosity objects with L_(14{-_195 keV)_ < 10^44^ erg s^-1^ Conclusions: Concerning the variability pattern, there is a tendency of unabsorbed or type 1 galaxies being less variable than the absorbed or type 2 objects at hardest X-rays. A more solid anti-correlation is found between variability and luminosity, which has been previously observed in soft X-rays, in the UV, and in the optical domain. Key words: galaxies: active, galaxies: Seyfert, X-rays:, galaxies, surveys
Retrieve 44 NED objects in this reference.
Please click here for ADS abstract

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