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

Journal
Date Issued
2017
Author(s)
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Bird, A. J.
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DOI
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 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.
Volume
469
Issue
4
Start page
3901
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2017MNRAS.469.3901S
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open.access
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