{
  "id": "2205.06696",
  "version": "v1",
  "published": "2022-05-13T15:05:17.000Z",
  "updated": "2022-05-13T15:05:17.000Z",
  "title": "Black Hole Spin Measurements Based on a Thin Disc Model with Finite Thickness I. An example study of MCG-06-30-15",
  "authors": [
    "Jiachen Jiang",
    "Askar B. Abdikamalov",
    "Cosimo Bambi",
    "Christopher S. Reynolds"
  ],
  "comment": "15 pages, 14 figures, accepted for publication in MNRAS",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We present a re-analysis of the XMM-Newton and NuSTAR observing campaign for the well-studied, X-ray-bright AGN MCG-06-30-15. In particular, we consider a disc model with finite thickness. By fitting the disc reflection spectra in the data, we obtain a black hole spin of 0.87--0.99 (90\\% confidence range) after taking the thickness of the disc into consideration. Spectral models with a grid of mass accretion rate from 0 to $30\\%\\dot{M}_{\\rm Edd}$ are calculated for MCG-06-30-15. This result is obtained by considering a free disc reflection fraction parameter $f_{\\rm refl}$ and is consistent with previous measurements based on razor-thin disc models. Besides, an isotropic, point-like geometry, i.e. the `lamppost' geometry, is assumed for the corona in our model. We find that such a geometry overestimates $f_{\\rm refl}$ in the data. Therefore, thin disc models with consistent `lamppost' values of $f_{\\rm refl}$ provide a worse fit than ones with a free $f_{\\rm refl}$ parameter. We discuss possible reasons for the discrepancy between the observed and theoretical values of $f_{\\rm refl}$ at the end of the paper. Modifications for the over-simplified lamppost model might be needed when the thickness of the thin disc is considered in future work.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-05-13T15:05:17.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "black hole spin measurements",
      "thin disc model",
      "finite thickness",
      "example study",
      "free disc reflection fraction parameter"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 15,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}