Optical variability of the accretion disk around the intermediate-mass black hole ESO 243-49 HLX-1 during the 2012 outburst

N. A. Webb, O. Godet, K. Wiersema, J. P. Lasota, D. Barret, S. A. Farrell, T. J. Maccarone, M. Servillat

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

We present dedicated quasi-simultaneous X-ray (Swift) and optical (Very Large Telescope, V-, and R-band) observations of the intermediate-mass black hole candidate HLX-1 before and during the 2012 outburst. We show that the V-band magnitudes vary with time, thus proving that a portion of the observed emission originates in the accretion disk. Using the first quiescent optical observations of HLX-1, we show that the stellar population surrounding HLX-1 is fainter than V ∼ 25.1 and R ∼ 24.2. We show that the optical emission may increase before the X-ray emission consistent with the scenario proposed by Lasota et al. in which the regular outbursts could be related to the passage at periastron of a star circling the intermediate-mass black hole in an eccentric orbit, which triggers mass transfer into a quasi-permanent accretion disk around the black hole. Further, if there is indeed a delay in the X-ray emission we estimate the mass-transfer delivery radius to be ∼1011 cm.

Original languageEnglish
Article numberL9
JournalAstrophysical Journal Letters
Volume780
Issue number1
DOIs
StatePublished - Jan 1 2014

Keywords

  • accretion, accretion disks
  • binaries: close
  • black hole physics

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