Chasing candidate Supergiant Fast X-ray Transients in the 1,000 orbits INTEGRAL/IBIS catalog

Abstract

We report results from an investigation at hard X-rays (above 18 keV) and soft X-rays (below 10 keV) of a sample of X-ray transients located on the Galactic plane and detected with the bursticity method, as reported in the latest 1,000 orbits INTEGRAL/IBIS catalog. Our main aim has been to individuate those with X-rays characteristics strongly resembling Supergiant Fast X-ray Transients (SFXTs). As a result, we found four unidentified fast X-ray transients which now can be considered good SFXT candidates. In particular, three transients (IGR J16374-5043, IGR J17375-3022 and IGR J12341-6143) were very poorly studied in the literature before the current work, and our findings largely improved the knowledge of their X-ray characteristics. The other transient (XTE J1829-098) was previously studied in detail only below 10 keV, conversely the current work provides the first detailed study in outburst above 18 keV. In addition we used archival infrared observations of the transients to pinpoint, among the field objects, their best candidate counterpart. We found that their photometric properties are compatible with an early type spectral classification, further supporting our proposed nature of SFXTs. Infrared spectroscopy is advised to confirm or disprove our interpretation. The reported findings allowed a significant increase of the sample of candidate SFXTs known to date, effectively doubling their number.

Accepted for publication in MNRAS. 12 pages, 10 figures, 4 tables

References in corpus (11)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The UKIDSS Galactic Plane Survey
• The 3rd IBIS/ISGRI soft gamma-ray survey catalog
• Unveiling supergiant fast X-ray transient sources with INTEGRAL
• Towards a unified view of inhomogeneous stellar winds in isolated supergiant stars and supergiant high mass X-ray binaries
• IGR J18483-0311: an accreting X-ray pulsar observed by INTEGRAL
• A search for counterparts to massive X-ray binaries using photometric catalogues
• X-ray Observations and Infrared Identification of the Transient 7.8 s X-ray Binary Pulsar XTE J1829-098
• INTEGRAL discovery of unusually long broad-band X-ray activity from the Supergiant Fast X-ray Transient IGR J18483-0311
• IGR J17503-2636: a candidate supergiant fast X-ray transient
• First hard X-ray detection and broad band X-ray study of the unidentified transient AX J1949.8+2534

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• Constraints on cyclotron features and accretion regime in the high-mass X-ray binary 4U 1700-37 from NuSTAR