{
  "id": "2301.04002",
  "version": "v1",
  "published": "2023-01-10T14:49:52.000Z",
  "updated": "2023-01-10T14:49:52.000Z",
  "title": "X-ray Polarimetry for Black Hole Spin Measurements]{X-ray Polarimetry as a Tool to Measure the Black Hole Spin in Microquasars: Simulations of IXPE Capabilities",
  "authors": [
    "Romana Mikusincova",
    "Michal Dovciak",
    "Michal Bursa",
    "Niccolo Di Lalla",
    "Giorgio Matt",
    "Jiri Svoboda",
    "Roberto Taverna",
    "Wenda Zhang"
  ],
  "comment": "11 pages, 10 figures",
  "doi": "10.1093/mnras/stad077",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Measurements of the angular momentum (spin) of astrophysical black holes are extremely important, as they provide information on the black hole formation and evolution. We present simulated observations of a X-ray binary system with the Imaging X-ray Polarimetry Explorer (IXPE), with the aim to study the robustness of black hole spin and geometry measurements using X-ray polarimetry. As a representative example, we used the parameters of GRS 1915+105 in its former unobscured, soft state. In order to simulate the polarization properties, we modeled the source emission with a multicolor blackbody accounting for thermal radiation from the accretion disk, including returning radiation. Our analysis shows that the polarimetric observations in the X-ray waveband will be able to estimate both spin and inclination of the system with a good precision (without returning radiation we obtained for the lowest spin $\\Delta a \\leq 0.4$ (0.4/0.998 $\\sim$ 40 \\%) for spin and $\\Delta i \\leq 30^\\circ$ (30$^\\circ$/70$^\\circ$ $\\sim$ 43\\%) for inclination, while for the higher spin values we obtained $\\Delta a \\leq 0.12$ ($\\sim$ 12 \\%) for spin and $\\Delta i \\leq 20^\\circ$ ($ \\sim $ 29\\%) for inclination, within 1$ \\sigma $ errors). When focusing on the case of returning radiation and treating inclination as a known parameter, we were able to successfully reconstruct spin and disk albedo in $\\Delta a \\leq 0.15$ ($\\sim$ 15 \\%) interval and $\\Delta$ albedo $\\leq 0.45$ (45 \\%) intervals within 1$ \\sigma $ errors. We conclude that X-ray polarimetry will be a useful tool to constrain black hole spins, in addition to timing and spectral-fitting methods.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-01-10T14:49:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "black hole spin measurements",
      "ixpe capabilities",
      "returning radiation",
      "microquasars",
      "inclination"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 11,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}