{
  "id": "1608.01659",
  "version": "v1",
  "published": "2016-08-04T19:47:51.000Z",
  "updated": "2016-08-04T19:47:51.000Z",
  "title": "Controversy of the GRO J1655-40 black hole mass and spin estimates and its possible solutions",
  "authors": [
    "Zdeněk Stuchlík",
    "Martin Kološ"
  ],
  "comment": "10 pages, 3 figures, 2 tables",
  "journal": "The Astrophysical Journal, Volume 825, Issue 1, article id. 13, pp. (2016)",
  "doi": "10.3847/0004-637X/825/1/13",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Estimates of the black hole mass $M$ and dimensionless spin $a$ in the microquasar GRO J1655-40 implied by strong gravity effects related to the timing and spectral measurements are controversial, if the mass restriction determined by the dynamics related to independent optical measurements, $M_{\\rm opt}=(5.4\\pm0.3) M_{\\odot}$, are applied. The timing measurements of twin high-frequency (HF) quasiperiodic oscillations (QPOs) with frequency ratio $3:2$ and the simultaneously observed low-frequency (LF) QPO imply the spin in the range $a\\in(0.27-0.29)$ if models based on the frequencies of the geodesic epicyclic motion are used to fit the timing measurements, and correlated creation of the twin HF QPOs and the LF QPO at a common radius is assumed. On the other hand, the spectral continuum method implies $a\\in(0.65-0.75)$, and the Fe-line-profile method implies $a\\in(0.94-0.98)$. This controversy can be cured, if we abandon the assumption of the occurrence of the twin HF QPOs and the simultaneously observed LF QPO at a common radius. We demonstrate that the epicyclic resonance model of the twin HF QPOs is able to predict the spin in agreement with the Fe-profile method, but no model based on the geodesic epicyclic frequencies can be in agreement with the spectral continuum method. We also show that the non-geodesic string loop oscillation model of twin HF QPOs predicts spin $a>0.3$ under the optical measurement limit on the black hole mass, in agreement with both the spectral continuum and Fe-profile methods.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-08-04T19:47:51.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "black hole mass",
      "spin estimates",
      "string loop oscillation model",
      "spectral continuum method",
      "measurement"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}