{
  "id": "2401.12860",
  "version": "v1",
  "published": "2024-01-23T15:51:49.000Z",
  "updated": "2024-01-23T15:51:49.000Z",
  "title": "X-Ray Variability of SDSS Quasars Based on the SRG/eROSITA All-Sky Survey",
  "authors": [
    "S. A. Prokhorenko",
    "S. Yu. Sazonov",
    "M. R. Gilfanov",
    "S. A. Balashev",
    "I. F. Bikmaev",
    "A. V. Ivanchik",
    "P. S. Medvedev",
    "A. A. Starobinsky",
    "R. A Sunyaev"
  ],
  "comment": "Accepted for publication in MNRAS, 19 pages, 5 tables, 15 figures",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We examine the long-term (rest-frame time scales from a few months to $\\sim 20$ years) X-ray variability of a sample of 2344 X-ray bright quasars from the SDSS DR14Q Catalogue, based on the data of the SRG/eROSITA All-Sky Survey complemented for $\\sim 7$% of the sample by archival data from the XMM-Newton Serendipitous Source Catalogue. We characterise variability by a structure function, $SF^2(\\Delta t)$. We confirm the previously known anti-correlation of the X-ray variability amplitude with luminosity. We also study the dependence of X-ray variability on black hole mass, $M_{\\rm BH}$, and on an X-ray based proxy of the Eddington ratio, $\\lambda_{\\rm X}$. Less massive black holes prove to be more variable for given Eddington ratio and time scale. X-ray variability also grows with decreasing Eddington ratio and becomes particularly strong at $\\lambda_{\\rm X}$ of less than a few per cent. We confirm that the X-ray variability amplitude increases with increasing time scale. The $SF^2(\\Delta t)$ dependence can be satisfactorily described by a power law, with the slope ranging from $\\sim 0$ to $\\sim 0.4$ for different ($M_{\\rm BH}$, $\\lambda_{\\rm X}$) subsamples (except for the subsample with the lowest black hole mass and lowest Eddington ratio, where it is equal to $1.1\\pm 0.4$)",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-01-23T15:51:49.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "srg/erosita all-sky survey",
      "sdss quasars",
      "eddington ratio",
      "time scale",
      "lowest black hole mass"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 19,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}