{
  "id": "2308.01841",
  "version": "v1",
  "published": "2023-08-03T16:05:58.000Z",
  "updated": "2023-08-03T16:05:58.000Z",
  "title": "Universality of coronal properties in accreting black holes across mass and accretion rate",
  "authors": [
    "Sudip Chakraborty",
    "Ajay Ratheesh",
    "Francesco Tombesi",
    "Rodrigo Nemmen",
    "Srimanta Banerjee"
  ],
  "comment": "9 pages, 3 figures. Shortened abstract. Accepted for publication in A&A Letters",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Through their radio loudness, lack of thermal UV emission from the accretion disk and power-law dominated spectra, Low Luminosity AGN (LLAGN) display similarity with the hard state of stellar-mass black hole X-Ray Binaries (BHBs). In this work we perform a systematic hard X-ray spectral study of a carefully selected sample of unobscured LLAGN using archival $NuSTAR$ data, to understand the central engine properties in the lower accretion regime. We analyze the $NuSTAR$ spectra of a sample of 16 LLAGN. We model the continuum emission with detailed Comptonization models. We find a strong anti-correlation between the optical depth and the electron temperature of the corona, previously also observed in the brighter Seyferts. This anti-correlation is present irrespective of the shape of the corona, and the slope of this anti-correlation in the log space for LLAGN (0.68-1.06) closely matches that of the higher accretion rate Seyferts (0.55-1.11) and hard state of BHBs ($\\sim$0.87). This anti-correlation may indicate a departure from a fixed disk-corona configuration in radiative balance. Our result, therefore, demonstrates a possible universality in Comptonization processes of black hole X-ray sources across multiple orders of magnitude in mass and accretion rate.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-08-03T16:05:58.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "accretion rate",
      "accreting black holes",
      "coronal properties",
      "stellar-mass black hole x-ray binaries",
      "systematic hard x-ray spectral study"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}