[ Previous | Next | ADS ]

Likely X-ray counterparts of newly discovered INTEGRAL/IBIS sources

ATel #4165; R. Landi, L. Bassani, N. Masetti (INAF - IASF Bologna), A. Bazzano, M. Fiocchi (INAF - IAPS Rome), A. J. Bird, S. Drave (University of Southampton)
on 12 Jun 2012; 15:23 UT
Credential Certification: Raffaella Landi (landi@iasfbo.inaf.it)

Subjects: X-ray, Gamma Ray, Request for Observations

Referred to by ATel #: 6793

With respect to the recent INTEGRAL/IBIS 9-year Galactic Hard X-ray Survey (Krivonos et al. 2012, arXiv:1205.3941), we use archival Swift/XRT observations in conjunction with multi-wavelength information to find the likely counterparts for two newly discovered INTEGRAL sources: IGR J14091-6108 and IGR J14257-6117.

IGR J14091-6108
XRT pointed at the region surrounding this IBIS source for a total exposure of ~8.7 ks. Within the 90% IBIS error circle, XRT detects one X-ray source, detected at 10.7 and 9.1 sigma confidence level (c.l.) in the 0.3-10 keV energy range and above 3 keV, respectively. This object is located at RA(J2000) = 14h 08m 46.34s and Dec(J2000) = -61d 07m 55.5s (4 arcsec uncertainty at 90% c.l.). Within the XRT error circle, there are two USNO-B1 sources, USNO-B1 0288-0488487 and USNO-B1 0288-0488489 having magnitudes R ~16 and ~16.3 respectively; neither object has a counterpart in the 2MASS catalogue.

The X-ray spectrum is well modelled with a power law (NH(Gal) = 1.8 x 1022 cm-2) having a flat (Gamma ~1.3) spectrum and an observed 2-10 keV flux of ~1.9 x 10-12 erg cm-2 s-1.

IGR J14257-6117
This object is associated with the unidentified Swift/BAT object SWIFT J1424.8-6122 (Krivonos et al. 2012). The region was observed by Swift/XRT for a total exposure of ~3.6 ks. Within the IBIS and BAT error circles, XRT detects a source at RA(J2000) = 14h 25m 07.70s and Dec(J2000) = -61d 18m 58.5s (3.7 arcsec uncertainty at 90% c.l.). This object, which is detected at 17 sigma c.l. in the 0.3-10 keV energy range and still observed at energies above 3 keV with a statistical significance of 13.4 sigma c.l., coincides with a USNO-B1 object (USNO-B1 0286-0489119) having a magnitude R ~17; it is also listed in the 2MASS catalogue (2MASS J14250758-6118578), with magnitudes J ~16.2, H ~14.8, and K ~14.4.

The model that provides the best-fit to the X-ray data consists of a black body component (kT ~0.1 keV) and a flat (Gamma ~0.95) power law (NH(Gal) = 1.65 x 1022 cm-2). The observed 2-10 keV flux is ~4.4 x 10-12 erg cm-2 s-1.

Based on source locations, the X-ray spectral properties, and lack of an evident radio counterpart we favour a Galactic nature for both sources.

We acknowledge the use of public data from the Swift data archive.