{
  "id": "1508.03155",
  "version": "v1",
  "published": "2015-08-13T09:20:19.000Z",
  "updated": "2015-08-13T09:20:19.000Z",
  "title": "X-ray outbursts of ESO 243-49 HLX-1: comparison with Galactic low-mass X-ray binary transients",
  "authors": [
    "Zhen Yan",
    "Wenda Zhang",
    "Roberto Soria",
    "Diego Altamirano",
    "Wenfei Yu"
  ],
  "comment": "13 papges, 12 figures, accepted for publication in ApJ",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We studied the outburst properties of the hyper-luminous X-ray source ESO 243-49 HLX-1, using the full set of Swift monitoring observations. We quantified the increase in the waiting time, recurrence time and e-folding rise timescale along the outburst sequence, and the corresponding decrease in outburst duration, total radiated energy, and e-folding decay timescale, which confirms previous findings. HLX-1 spends less and less time in outburst and more and more time in quiescence, but its peak luminosity remains approximately constant. We compared the HLX-1 outburst properties with those of bright Galactic low-mass X-ray binary transients (LMXBTs). Our spectral analysis strengthens the similarity between state transitions in HLX-1 and those in Galactic LMXBTs. We also found that HLX-1 follows the nearly linear correlations between the hard-to-soft state transition luminosity and the peak luminosity, and between the rate of change of X-ray luminosity during the rise phase and the peak luminosity, which indicates that the occurrence of the hard-to-soft state transition of HLX-1 is similar to those of Galactic LMXBTs during outbursts. We found that HLX-1 does not follow the correlations between total radiated energy and peak luminosity, and between total radiated energy and e-folding rise/decay timescales we had previously identified in Galactic LMXBTs. HLX-1 would follow those correlations if the distance were several hundreds of kpc. But invoking a much closer distance for HLX-1 is not a viable solution to this problem, as it introduces other more serious inconsistencies with the observations.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-08-13T09:20:19.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "galactic low-mass x-ray binary transients",
      "peak luminosity",
      "x-ray outbursts",
      "total radiated energy",
      "luminosity remains approximately constant"
    ],
    "publication": {
      "doi": "10.1088/0004-637X/811/1/23"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1387732
    }
  }
}