Hard X-ray spectra of AGN in the INTEGRAL complete sample

TL;DR

This study analyzes the hard X-ray spectra of a complete AGN sample detected by INTEGRAL, comparing data with Swift/BAT, revealing spectral features, variability, and parameter ranges, and suggesting similar powering mechanisms in different AGN types.

Contribution

It provides a comprehensive spectral analysis of a complete AGN sample, cross-calibrates INTEGRAL and Swift/BAT data, and explores spectral complexity and parameter distributions.

Findings

14% of sources show flux variability

Type 1 and Type 2 AGN have similar photon indices

Most AGN have photon index between 1 and 2, and cut-off energy between 30 and 300 keV

Abstract

In this paper, we present the hard X-ray spectral analysis of a complete sample of AGN de- tected by INTEGRAL/IBIS. In conjunction with IBIS spectra, we make use of Swift/BAT data, with the aim of cross-calibrating the two instruments, studying source variability and con- straining some important spectral parameters. We find that flux variability is present in at least 14% of the sample, while spectral variability is found only in one object. There is general good agreement between BAT and IBIS spectra, despite a systematic mismatch of about 22% in normalisation. When fitted with a simple power-law model, type 1 and type 2 sources appear to have very similar average photon indices, suggesting that they are powered by the same mechanism. As expected, we also find that a simple power-law does not always describe the data sufficiently well, thus indicating a certain degree of spectral complexity, which can be ascribed to features like a high energy cut-off and/or a reflection component. Fixing the reflection to be 0, 1 or 2, we find that our sample covers quite a large range in photon indices as well as cut-off energies; however, the spread is due only to a small number of objects, while the majority of the AGN lie within well defined boundaries of photon index (1<{\Gamma}<2) and cut-off energy (30<Ecut<300 keV).