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arXiv · 1904.09762

Chandra, MDM, Swift, and NuSTAR observations confirming the SFXT nature of AX J1949.8+2534

Jeremy Hare·Jules P. Halpern·Maica Clavel·Jonathan E. Grindlay·Farid Rahoui·John A. Tomsick
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Abstract

AX J1949.8+2534 is a candidate supergiant fast X-ray transient (SFXT) observed in outburst by INTEGRAL (IGR J19498+2534). We report on the results of six Neil Gehrels Swift-XRT, one Chandra, and one NuSTAR observation of the source. We find evidence of rapid X-ray variability on a few ks timescales. Fortunately, Chandra observed the source in a relatively bright state, allowing us to confidently identify the optical/NIR counterpart of the source. We also obtained an optical spectrum of this counterpart, which shows an H$α$ emission line and He I absorption features. The photometry and spectrum of the source allow us to constrain its distance, $\sim7-8$ kpc, and reddening, $A_V=8.5-9.5$. We find that the star is likely an early B-type Ia supergiant, confirming that AX J1949.8+2534 is indeed an SFXT.

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Jeremy Hare, Jules P. Halpern, Maica Clavel, Jonathan E. Grindlay, Farid Rahoui, John A. Tomsick. 2019-04-22. Chandra, MDM, Swift, and NuSTAR observations confirming the SFXT nature of AX J1949.8+2534. https://doi.org/10.3847/1538-4357%2Fab1cbe

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