{
  "id": "2411.07459",
  "version": "v1",
  "published": "2024-11-12T00:51:49.000Z",
  "updated": "2024-11-12T00:51:49.000Z",
  "title": "The long-term variability of a population of ULXs monitored by Chandra",
  "authors": [
    "Hannah P. Earnshaw",
    "Gauri Patti",
    "Murray Brightman",
    "Rajath Sathyaprakash",
    "Dominic J. Walton",
    "Felix Fuerst",
    "Timothy P. Roberts",
    "Fiona A. Harrison"
  ],
  "comment": "7 pages, 4 figures, to be published in Proceedings of the XMM-Newton Workshop 2024 \"The X-ray Mysteries of Neutron Stars and White Dwarfs\", Astronomische Nachrichten, in press",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "We present preliminary results of a Chandra Large Program to monitor the ultraluminous X-ray source (ULX) populations of three nearby, ULX-rich galaxies over the course of a year, finding the ULX population to show a variety of long-term variability behaviours. Of a sample of 36 ULXs, some show persistent or moderately variable flux, often with a significant relationship between hardness and luminosity, consistent with a supercritically accreting source with varying accretion rates. Six show very high-amplitude variability with no strong relationship between luminosity and hardness, though not all of them show evidence of any long-term periodicity, nor of the bimodal distribution indicative of the propeller effect. We find evidence of additional eclipses for two previously-identified eclipsing ULXs. Additionally, many sources that were previously identified as ULXs in previous studies were not detected at ULX luminosities during our monitoring campaign, indicating a large number of transient ULXs.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-11-12T00:51:49.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "population",
      "chandra large program",
      "long-term variability behaviours",
      "luminosity",
      "additional eclipses"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}