Multiwavelength spectral evolution during the 2011 outburst of the very faint X-ray transient swift j1357.2-0933

Armas M. Padilla, N. Degenaar, D. M. Russell, R. Wijnands

Research output: Contribution to journalArticlepeer-review


We report our multiwavelength study of the 2011 outburst evolution of the newly discovered black hole candidateX-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 ~1035(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 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, and we do not detect X-ray reprocessing on the disc surface. 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.

Original languageEnglish (US)
Pages (from-to)3083-3088
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Feb 1 2013


  • Accretion
  • Accretion discs - stars
  • Binaries
  • Individual
  • Swift J1357.2-0933 -X-rays

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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