We present the results from INTEGRAL and Swift/XRT observations of the hitherto poorly studied unidentified X-ray transient AX J1949.8+2534, and on archival multiwavelength observations of field objects. Bright hard X-ray outbursts have been discovered above 20 keV for the first time, the measured duty cycle and dynamic range are of the order of ∼4 per cent and ≥ 630, respectively. The source was also detected during a low soft X-ray state (∼2 × 10-12 erg cm-2 s-1) thanks to a Swift/XRT followup, which allowed for the first time to perform a soft X-ray spectral analysis as well as significantly improve the source positional uncertainty from arcminute to arcsecond size. From archival near-infrared data, we pinpointed two bright objects as most likely counterparts whose photometric properties are compatible with an early-type spectral nature. This strongly supports a high-mass X-ray binary (HMXB) scenario for AX J1949.8+2534, specifically a Supergiant Fast X-ray Transient (more likely) or alternatively a Be HMXB.
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2017
- X-rays: binaries;
- X-rays: individual: AX J1949.8-2534;
- Astrophysics - High Energy Astrophysical Phenomena
- Accepted for publication in MNRAS. 8 pages, 6 figures, 4 tables