{
  "id": "1308.1682",
  "version": "v1",
  "published": "2013-08-07T20:00:26.000Z",
  "updated": "2013-08-07T20:00:26.000Z",
  "title": "Can the 62 day X-ray period of the Ultraluminous X-ray source M82 X-1 be due to a precessing accretion disk?",
  "authors": [
    "Dheeraj R. Pasham",
    "Tod E. Strohmayer"
  ],
  "comment": "Accepted for publication in ApJ Letters",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We have analyzed all archival RXTE/PCA monitoring observations of the ultraluminous X-ray source (ULX) M82 X-1 in order to study the properties of its 62 day X-ray period (Kaaret & Feng 2007). Based on its high coherence it has been argued that the observed period is the orbital period of the binary. Utilizing a much longer data set than in previous studies we find: (1) The phase-resolved X-ray (3-15 keV) spectra -- modeled with a thermal accretion disk and a power-law -- suggest that the accretion disk's contribution to the total flux is strongly modulated with phase. (2) Suggestive evidence for a sudden phase shift--of approximately 0.4 in phase (25 days)-- between the first and the second halves of the light curve separated by roughly 1000 days. If confirmed, the implied timescale to change the period is ~ 10 yrs, which is exceptionally fast for an orbital phenomenon. These two independent pieces of evidence are consistent with the periodicity being due to a precessing accretion disk, similar to the super-orbital periods observed in systems like Her X-1, LMC X-4, and SS433. However, the timing evidence for a change in the period needs to be confirmed with additional observations. This should be possible with further monitoring of M82 with instruments such as the Swift X-ray telescope (XRT).",
  "revisions": [
    {
      "version": "v1",
      "updated": "2013-08-07T20:00:26.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "ultraluminous x-ray source m82",
      "day x-ray period",
      "precessing accretion disk",
      "accretion disks contribution",
      "swift x-ray telescope"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/2041-8205/774/2/L16",
      "journal": "The Astrophysical Journal",
      "year": 2013,
      "month": "Sep",
      "volume": 774,
      "number": 2
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1246998,
      "adsabs": "2013ApJ...774L..16P"
    }
  }
}