Update of the INTEGRAL/IBIS AGN catalogue: deeper on the Galactic plane and wider beyond

TL;DR

This paper updates the INTEGRAL/IBIS AGN catalogue by adding 83 new active galaxies, many behind the Galactic plane, with detailed X-ray spectral analysis and classification, enhancing the sample for high-energy astrophysics research.

Contribution

The paper provides the first comprehensive update of the INTEGRAL AGN catalogue with new detections, spectral characterizations, and refined classifications, especially for sources behind the Galactic plane.

Findings

Added 83 new AGN, increasing the total by 19%.

Identified AGN among candidates using multi-wavelength diagnostics.

Confirmed optical classifications and redshifts for 12 sources.

Abstract

In this work we have updated the list of AGN detected by INTEGRAL taking into account the new objects listed in the last published INTEGRAL/IBIS survey. We have collected 83 new AGN increasing the number of INTEGRAL detected active galaxies (436) by 19%. Half of these new additions are located behind the Galactic plane; for most of them we have full X-ray coverage obtained through archival data from Swift/XRT, XMM-Newton and NuSTAR. This allowed us to associate each high-energy emitter with a single or multiple X-ray counterpart/s and characterise the spectral shape of these new AGN by estimating the photon index, the intrinsic absorption and the 2-10 keV flux. A few cases where two soft X-ray counterparts fall within the INTEGRAL error circle and at least one is classified as an AGN have been found and discussed in detail. Thirty-four sources originally listed as AGN candidates or unidentified objects have been recognised as AGN by employing three diagnostic tests: WISE colours, radio emission and morphology. For 12 sources, among the 34 AGN candidates, we reduced optical spectra and confirmed their AGN nature, providing also their optical class and redshift. This paper is part of an on-going effort to keep the INTEGRAL AGN catalogue updated in order to provide the scientific community with a hard X-ray selected sample of active galaxies well classified and spectrally characterised.