Unveiling the nature of INTEGRAL objects through optical spectroscopy. V. Identification and properties of 21 southern hard X-ray sources

TL;DR

This study uses optical spectroscopy to identify the nature of 21 previously unknown southern hard X-ray sources detected by INTEGRAL, revealing their classifications and physical properties.

Contribution

It provides new classifications and physical parameters for 21 INTEGRAL sources, demonstrating the effectiveness of optical spectroscopy combined with multiwavelength data.

Findings

5 are magnetic Cataclysmic Variables

4 are High-Mass X-ray Binaries, including one in the LMC

12 are Active Galactic Nuclei

Abstract

Optical spectroscopic identification of the nature of 21 unidentified southern hard X-ray objects is reported here in the framework of our campaign aimed at determining the nature of newly-discovered and/or unidentified sources detected by INTEGRAL. Our results show that 5 of these objects are magnetic Cataclysmic Variables (CVs), 4 are High-Mass X-ray Binaries (HMXBs; one of which is in the Large Magellanic Cloud) and 12 are Active Galactic Nuclei (AGNs). When feasible, the main physical parameters for these hard X-ray sources are also computed using the multiwavelength information available in the literature. These identifications further underscore the importance of INTEGRAL in the study of the hard X-ray spectrum of AGNs, HMXBs and CVs, and the usefulness of a strategy of catalogues cross-correlation plus optical spectroscopy to securely pinpoint the actual nature of the X-ray sources detected with INTEGRAL.