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arXiv · 1207.5805

Multiwavelength spectral evolution during the 2011 outburst of the very faint X-ray transient Swift J1357.2-0933

M. Armas Padilla·N. Degenaar·D. M. Russell·R. Wijnands
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Abstract

We report our multiwavelength study of the 2011 outburst evolution of the newly discovered black hole candidate X-ray binary Swift J1357.2-0933. We analysed the Swift X-ray telescope and Ultraviolet/Optical telescope (UVOT) data taken during the ~7 months duration of the outburst. It displayed a 2-10 keV X-ray peak luminosity of ~1E35(D/1.5 kpc)^2 erg s-1 which classifies the source as a very faint X-ray transient. We found that the X-ray spectrum at the peak was consistent with the source being in the hard state, but it softened with decreasing luminosity, a common behaviour of black holes at low luminosities or returning to quiescence from the hard state. The correlations between the simultaneous X-ray and ultraviolet/optical data suggest a system with a black hole accreting from a viscous disc that is not irradiated. The UVOT filters provide the opportunity to study these correlations up to ultraviolet wavelengths a regime so far unexplored. If the black hole nature is confirmed, Swift J1357.2-0933 would be one of the very few established black hole very-faint X-ray transients.

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M. Armas Padilla, N. Degenaar, D. M. Russell, R. Wijnands. 2012-11-06. Multiwavelength spectral evolution during the 2011 outburst of the very faint X-ray transient Swift J1357.2-0933. https://doi.org/10.1093/mnras%2Fsts255

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