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arXiv · 1705.03269

First hard X-ray detection and broad band X-ray study of the unidentified transient AX J1949.8+2534

V. Sguera·L. Sidoli·A. Paizis·N. Masetti·A. J. Bird·A. Bazzano
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Abstract

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% and >630, respectively. The source was also detected during a low soft X-ray state (2x10E-12 erg cmE-2 sE-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.

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V. Sguera, L. Sidoli, A. Paizis, N. Masetti, A. J. Bird, A. Bazzano. 2017-05-09. First hard X-ray detection and broad band X-ray study of the unidentified transient AX J1949.8+2534. https://doi.org/10.1093/mnras%2Fstx1111

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