{
  "id": "1603.05504",
  "version": "v1",
  "published": "2016-02-29T09:29:10.000Z",
  "updated": "2016-02-29T09:29:10.000Z",
  "title": "X-Ray Spectra of The High-Mass X-RAY Binary 4U~1700-37 using BeppoSAX, Suzaku and RXTE Observations",
  "authors": [
    "Elena Seifina",
    "Lev Titarchuk",
    "Nikolai Shaposhnikov"
  ],
  "comment": "18 pages, 7 figures, 7 Tables, accepted by the ApJ, on February 29, 2016",
  "categories": [
    "astro-ph.HE",
    "astro-ph.SR"
  ],
  "abstract": "We present an X-ray spectral analysis of the high-mass binary 4U~1700-37 during its hard-soft state evolution. We use the BeppoSAX, Suzaku and RXTE (Rossi X-ray Timing Explorer), Suzaku and BeppoSAX observations for this investigation. We argue that the X-ray broad-band spectra during all spectral states can be adequately reproduced by a model, consisting of a low-temperature Blackbody component, two Comptonized components both due to the presence of a Compton cloud (CC) that up-scatters seed photons of $T_{s1}$~< 1.4 keV, and $T_{s2}<$1 keV, and an iron-line component. We find using this model that the photon power-law index is almost constant, $\\Gamma_{1}\\sim 2$ for all spectral states. However, $\\Gamma_{2}$ shows a behavior depending on the spectral state. Namely, $\\Gamma_{2}$ is quasi-constant at the level of $\\Gamma_{2}\\sim 2$ while the CC plasma temperature $kT^{(2)}_e$ is less than 40 keV; on the other hand, $\\Gamma_{2}$ is in the range of $1.3<\\Gamma_{2}<2$, when $kT^{(2)}_e$ is greater than 40 keV. We explain this quasi-stability of $\\Gamma$ during most of hard-soft transitions of 4U~1700-37 in a framework of the model in which the resulting spectrum is described by two Comptonized components. We find that these Comptonized spectral components of the HMXB 4U~1700-37 are similar to those previously found in NS sources. This index dependence versus both mass accretion rate and $kT_e$ revealed in 4U~1700-37 is a universal observational evidence for the presence of a NS in 4U 1700-37.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-02-29T09:29:10.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "high-mass x-ray binary",
      "rxte observations",
      "spectral state",
      "hard-soft state evolution",
      "x-ray spectral analysis"
    ],
    "publication": {
      "doi": "10.3847/0004-637X/821/1/23"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 18,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1429635
    }
  }
}