{
  "id": "1905.04440",
  "version": "v1",
  "published": "2019-05-11T03:53:55.000Z",
  "updated": "2019-05-11T03:53:55.000Z",
  "title": "NICER Observations of the 2018 Outburst of XTE J1810-197",
  "authors": [
    "Tolga Guver",
    "Ersin Gogus",
    "Eda Vurgun",
    "Teruaki Enoto",
    "Keith C. Gendreau",
    "Takanori Sakamoto",
    "Eric V. Gotthelf",
    "Zaven Arzoumanian",
    "Sebastien Guillot",
    "Gaurava K. Jaisawal",
    "Christian Malacaria",
    "Walid A. Majid"
  ],
  "comment": "Accepted for publication in the Astrophysical Journal Letters",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We present the earliest available soft X-ray observations of XTE J1810-187, the prototypical transient magnetar, obtained 75--84 days after its 2018 outburst with the Neutron Star Interior Composition Explorer (NICER). Using a series of observations covering eight days we find that its decreasing X-ray flux is well-described by either a blackbody plus power-law or a two-blackbody spectral model. The 2-10 keV flux of the source varied from (1.206+/-0.007)x10^{-10} to (1.125+/-0.004)x10^{-10} erg s^{-1} cm^{-2}, a decrease of about 7% within our observations and 44% from that measured 7-14 days after the outburst with NuSTAR. We confirm that the pulsed fraction and spin pulse phase of the neutron star are energy dependent up to at least 8 keV. Phase resolved spectroscopy of the pulsar suggests magnetospheric variations relative to the line of sight.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-05-11T03:53:55.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "nicer observations",
      "neutron star interior composition explorer",
      "two-blackbody spectral model",
      "soft x-ray observations",
      "spin pulse phase"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}