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Title: OPTICAL VARIABILITY OF THE ACCRETION DISK AROUND THE INTERMEDIATE-MASS BLACK HOLE ESO 243-49 HLX-1 DURING THE 2012 OUTBURST

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 ∼10{sup 11} cm.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Université de Toulouse, UPS-OMP, IRAP, Toulouse (France)
  2. University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
  3. Institut d'Astrophysique de Paris, UMR 7095, CNRS, UPMC Université Paris 06, 98bis Boulevard Arago, F-75014 Paris (France)
  4. Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)
  5. Department of Physics, Box 41051, Texas Tech University, Lubbock TX 79409-1051 (United States)
  6. Laboratoire AIM (CEA/DSM/IRFU/SAp, CNRS, Université Paris Diderot), CEA Saclay, Bat. 709, F-91191 Gif-sur-Yvette (France)
Publication Date:
OSTI Identifier:
22364076
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 780; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ASTROPHYSICS; BLACK HOLES; MASS TRANSFER; ORBITS; PHOTON EMISSION; STARS; TELESCOPES; X RADIATION