Hard X-ray Variability of the Brightest Swift/BAT AGN
  Variability is one of the hallmarks of Active Galactic Nuclei. The Burst Alert Telescope onboard of Swift, with its homogeneous coverage of the sky is a formidable tool to study variability at hard X-rays. We present here the analysis of the 1-month binned Swift/BAT lightcurves of the 20 brightest Active Galactic Nuclei in the hard X-ray sky. The sample consists of 2 blazars, 3 radio galaxies, 6 Seyfert 1/1.5s, 8 Seyfert 2s and 1 Narrow Line Seyfert 1. We found that all the objects show variability, and most of them have a value of the fractional root mean squared variability amplitude of Fvar \sim 0.2 - 0.3. We did not find any significant correlation of Fvar with the column density or the luminosity in our sample. 
Claudio Ricci, Stephane Paltani, Simona Soldi, Thierry J.-L.   Courvoisier
astro-ph.HE astro-ph.CO astro-ph.GA