Hard X-ray Variability of the Brightest Swift/BAT AGN

TL;DR

This study analyzes the hard X-ray variability of the 20 brightest AGN observed by Swift/BAT over a month, revealing universal variability without correlation to column density or luminosity.

Contribution

First comprehensive analysis of short-term hard X-ray variability across diverse AGN types using Swift/BAT data.

Findings

All AGN show variability with Fvar ~ 0.2-0.3.

No significant correlation between variability and column density.

No correlation between variability and luminosity.

Abstract

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.