The AGN nature of three INTEGRAL sources: IGR J18249-3243, IGR J19443+2117 and IGR J22292+6647

TL;DR

This study identifies three previously unclassified INTEGRAL sources as active galactic nuclei (AGN) by analyzing multi-wavelength data, including X-ray, radio, optical, and infrared observations, revealing their spectral and morphological characteristics.

Contribution

The paper provides the first broad-band spectral and morphological analysis of three INTEGRAL sources, confirming their AGN nature through multi-wavelength data integration.

Findings

All three sources are bright radio objects with AGN-like spectra.

IGR J19443+2117 shows excess absorption beyond Galactic levels.

IGR J22292+6647 exhibits X-ray variability.

Abstract

The third INTEGRAL/IBIS survey has revealed several new hard X-ray sources, which are still unclassified. To identify these sources, we need to find their counterparts at other wavelengths and then study their nature. The capability of XRT on board Swift to localize the sources with a positional accuracy of few arcseconds allows the search for optical/UV, infrared and radio counterparts to be more efficient and reliable. We analysed all XRT observations available for three unidentified INTEGRAL sources, IGR J18249-3243, IGR J19443+2117 and IGR J22292+6647, localized their soft X-ray counterparts and searched for associations with objects in the radio band. We also combined X-/gamma-ray data, as well as all the available radio, infrared and optical/UV information, in order to provide a broad-band spectral characterization of each source and investigate its nature. All three sources are found to be bright and repeatedly observed radio objects, although poorly studied. The X-/gamma-ray spectrum of each source is well described by power laws with photon indices typical of AGN; only IGR J19443+2117 may have absorption in excess of the Galactic value, while IGR J22292+6647 is certainly variable at X-ray energies. IGR J18249-3243 has a complex radio morphology and a steep radio spectrum; the other two sources show flatter radio spectra and a more compact morphology. Overall, their radio, optical/UV and infrared characteristics, as well as their X-/gamma-ray properties, point to an AGN classification for all three objects.