Soft X-ray follow-up of five hard X-ray emitters

TL;DR

This study provides detailed soft X-ray spectral and timing analyses of five hard X-ray sources, confirming classifications, identifying counterparts, and suggesting extragalactic origin for one source, thereby enhancing understanding of their nature.

Contribution

First detailed soft X-ray spectral and timing study of five hard X-ray sources, including new counterpart identification and classification support.

Findings

Confirmed supergiant high mass X-ray binary IGR J08262-3736

Supported classification of IGR J17354-3255 and IGR J16328-4726 as Supergiant Fast X-ray Transients

Identified soft X-ray counterpart for IGR J17348-2045 and suggested extragalactic origin

Abstract

We studied the soft-X-ray emission of five hard-X sources: IGR J08262-3736, IGR J17354-3255, IGR J16328-4726, SAX J1818.6-1703 and IGR J17348-2045. These sources are: a confirmed supergiant high mass X-ray binary (IGR J08262-3736); candidates (IGR J17354-3255, IGR J16328- 4726) and confirmed (SAX J1818.6-1703) supergiant fast X-ray transients; IGR J17348-2045 is one of the as-yet unidentified objects discovered with INTEGRAL. Thanks to dedicated XMM-Newton observations, we obtained the first detailed soft X-ray spectral and timing study of IGR J08262-3736. The results obtained from the observations of IGR J17354-3255 and IGR J16328-4726 provided further support in favor of their association with the class of Supergiant Fast X-ray Transients. SAX J1818.6-1703, observed close to phase 0.5, was not detected by XMM-Newton, thus supporting the idea that this source reaches its lowest X-ray luminosity (~10^32 erg/s) around apastron. For IGR J17348-2045 we identified for the first time the soft X-ray counterpart and proposed the association with a close-by radio object, suggestive of an extragalactic origin. In this proceeding we discuss the results obtained from the XMM-Newton follow-up observations of all the five sources.