{
  "id": "0907.4352",
  "version": "v1",
  "published": "2009-07-24T18:42:43.000Z",
  "updated": "2009-07-24T18:42:43.000Z",
  "title": "Chandra Observations of 1RXS J141256.0+792204 (Calvera)",
  "authors": [
    "Andrew S. H. Shevchuk",
    "Derek B. Fox",
    "Robert E. Rutledge"
  ],
  "comment": "Submitted to ApJ. AASTeX, 19 pages, 2 figures",
  "categories": [
    "astro-ph.HE",
    "astro-ph.GA"
  ],
  "abstract": "We report the results of a 30 ks Chandra ACIS-S observation of the isolated compact object 1RXS J141256.0+792204 (Calvera). The X-ray spectrum is adequately described by an absorbed neutron star hydrogen atmosphere model with an effective temperature at infinity of 88.3 +/- 0.8 eV and radiation radius at infinity of 4.1 +/- 0.1 km/kpc. The best-fit blackbody spectrum yields parameters consistent with previous measurements; although the fit itself is not statistically acceptable, systematic uncertainties in the pile-up correction may contribute to this. We find marginal evidence for narrow spectral features in the X-ray spectrum between 0.3 and 1.0 keV. In one interpretation, we find evidence at 81%-confidence for an absorption edge at 0.64 (+0.08) (-0.06) keV with an equivalent width of ~70 eV; if this feature is real, it is reminiscent of features seen in the isolated neutron stars RX J1605.3+3249, RX J0720.4-3125, and 1RXS J130848.6+212708 (RBS 1223). In an alternative approach, we find evidence at 88%-confidence for an unresolved emission line at energy 0.53 +/- 0.02 keV, with an equivalent width of ~28 eV; the interpretation of this feature, if real, is uncertain. We search for coherent pulsations up to the Nyquist frequency of 1.13 Hz and set an upper limit of 8.0% rms on the strength of any such modulation. We derive an improved position for the source and set the most rigorous limits to-date on any associated extended emission on arcsecond scales. Our analysis confirms the basic picture of Calvera as the first isolated compact object in the ROSAT/Bright Source Catalog discovered in six years, the hottest such object known, and an intriguing target for multiwavelength study.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-07-24T18:42:43.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "chandra observations",
      "blackbody spectrum yields parameters consistent",
      "best-fit blackbody spectrum yields parameters",
      "isolated compact object",
      "neutron star hydrogen atmosphere model"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-637X/705/1/391",
      "journal": "The Astrophysical Journal",
      "year": 2009,
      "month": "Nov",
      "volume": 705,
      "number": 1,
      "pages": 391
    },
    "note": {
      "typesetting": "TeX",
      "pages": 19,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 826780,
      "adsabs": "2009ApJ...705..391S"
    }
  }
}