{
  "id": "1209.3883",
  "version": "v1",
  "published": "2012-09-18T09:11:03.000Z",
  "updated": "2012-09-18T09:11:03.000Z",
  "title": "Confirming the 115.5-day periodicity in the X-ray light curve of ULX NGC 5408 X-1",
  "authors": [
    "Xu Han",
    "Tao An",
    "Jun-Yi Wang",
    "Ji-Ming Lin",
    "Ming-Jie Xie",
    "Hai-Guang Xu",
    "Xiao-Yu Hong",
    "Sandor Frey"
  ],
  "comment": "6 pages, 2 figures, submitted to Research in Astronomy and Astrophysics (RAA)",
  "categories": [
    "astro-ph.HE",
    "astro-ph.SR"
  ],
  "abstract": "The Swift/XRT light curve of the ultraluminous X-ray (ULX) source NGC 5408 X-1 was re-analyzed with two new numerical approaches, Weighted Wavelet $Z$-transform (WWZ) and CLEANest, that are different from previous studies. Both techniques detected a prominent periodicity with a time scale of $115.5\\pm1.5$ days, in excellent agreement with the detection of the same periodicity first reported by Strohmayer (2009). Monte Carlo simulation was employed to test the statisiticak confidence of the 115.5-day periodicity, yielding a statistical significance of $> 99.98%$ (or $>3.8\\sigma$). The robust detection of the 115.5-day quasi-periodic oscillations (QPOs), if it is due to the orbital motion of the binary, would infer a mass of a few thousand $M_\\odot$ for the central black hole, implying an intermediate-mass black hole in NGC 5408 X-1.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2012-09-18T09:11:03.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray light curve",
      "ulx ngc",
      "periodicity",
      "swift/xrt light curve",
      "central black hole"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/1674-4527/12/12/001",
      "journal": "Research in Astronomy and Astrophysics",
      "year": 2012,
      "month": "Dec",
      "volume": 12,
      "pages": 1597
    },
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1186349,
      "adsabs": "2012RAA....12.1597H"
    }
  }
}