Review on Active Galactic Nuclei at hard X-ray energies

TL;DR

This review discusses the importance of hard X-ray surveys in studying active galactic nuclei, highlighting recent findings on their absorption properties, spectral features, and the potential for future research with INTEGRAL.

Contribution

It provides an updated analysis of AGN absorption characteristics and spectral properties using INTEGRAL and Swift/BAT data, emphasizing the spectral complexity and diversity of AGN.

Findings

Updated fraction of Compton thick AGN.

Spectral shape and complexity variations among AGN.

Insights into broad-band spectral features.

Abstract

Hard X-ray surveys are an important tool for the study of active galactic nuclei (AGN): they provide almost an unbiased view of absorption in the extragalactic population, allow the study of spectral features such as reflection and high energy cut-off which would otherwise be unexplored and favour the discovery of some blazars at high redshift. Here, we present the absorption properties of a large sample of INTEGRAL detected AGN, including an update on the fraction of Compton thick objects. For a sub-sample of 87 sources, which represent a complete set of bright AGN, we will discuss the hard X-ray (20-100 keV) spectral properties, also in conjunction with Swift/BAT 58 month data, providing information on BAT/IBIS cross-calibration constant, average spectral shape and spectral complexity. For this complete sample, we will also present broad-band data using soft X-ray observations, in order to explore the complexity of AGN spectra both at low and high energies and to highlight the variety of shapes. Future prospects for AGN studies with INTEGRAL will also be outlined.