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arXiv · 1601.03208

Discovery of a variable X-ray counterpart to HESS J1832-093: A new gamma-ray binary?

P. Eger·H. Laffon·P. Bordas·E. de Ona Whilhelmi·J. Hinton·G. Puehlhofer
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Abstract

The TeV gamma-ray point source HESSJ1832-093 remains unidentified despite extensive multi-wavelength studies. The gamma-ray emission could originate in a very compact pulsar wind nebula or an X-ray binary system composed of the X-ray source XMMU J183245-0921539 and a companion star (2MASS J18324516-0921545). To unveil the nature of XMMUJ183245-0921539 and its relation to HESSJ1832-093, we performed deeper follow-up observations in X-rays with Chandra and Swift to improve source localisation and to investigate time variability. We observed an increase of the X-ray flux by a factor ~6 in the Chandra data compared to previous observations. The source is point-like for Chandra and its updated position is only 0.3" offset from 2MASS J18324516-0921545, confirming the association with this infrared source. Subsequent Swift ToO observations resulted in a lower flux, again compatible with the one previously measured with XMM-Newton, indicating a variability timescale of the order of two months or shorter. The now established association of XMMU J183245-0921539 and 2MASS J18324516-0921545 and the observed variability in X-rays are strong evidence for binary nature of HESS J1832-093. Further observations to characterise the optical counterpart as well as to search for orbital periodicity are needed to confirm this scenario.

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P. Eger, H. Laffon, P. Bordas, E. de Ona Whilhelmi, J. Hinton, G. Puehlhofer. 2016-01-13. Discovery of a variable X-ray counterpart to HESS J1832-093: A new gamma-ray binary?. https://doi.org/10.1093/mnras%2Fstw125

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