{
  "id": "2505.02596",
  "version": "v1",
  "published": "2025-05-05T12:04:48.000Z",
  "updated": "2025-05-05T12:04:48.000Z",
  "title": "The Secular Periodic Evolution of X-ray Quasi-periodic Eruptions Driven by Star-disc Collisions",
  "authors": [
    "Jiajun Xian",
    "Fupeng Zhang",
    "Liming Dou",
    "Zhining Chen"
  ],
  "comment": "20 pages, 6 figures, accepted for publication in Astrophysical Journal",
  "categories": [
    "astro-ph.HE",
    "astro-ph.GA"
  ],
  "abstract": "We study the secular periodic evolution of quasi-periodic eruptions (QPEs) for GSN069 and eRO-QPE2 assuming that they are driven by star-disc collisions. We set up numerical simulations and compared them with the observed periodic decay of $\\sim -3160\\pm720$ s yr$^{-1}$ in GSN069 and $\\sim -370\\pm40$ s yr$^{-1}$ in eRO-QPE2. We find that: (1) Stellar mass black holes are unlikely the orbiters in these two sources, as their periodic decay are on the order of $<10$ s yr$^{-1}$; (2) A naked degenerate core (including white dwarf) is unlikely the orbiter in GSN069, as the decay is on the order of $<200$ s yr$^{-1}$. However, it is possible in eRO-QPE2, although the required surface density of the accretion disc is relatively high (e.g., $\\Sigma\\gtrsim10^7\\sim 10^8$ g cm$^{-2}$); (3) Both the orbiters in GSN069 and eRO-QPE2 can be solar-like main-sequence stars (MSs). However, each collision can lead to gradual ablation of the stellar envelope in the order of $10^{-5}\\sim 10^{-3}M_\\odot$. To reproduce the observed decay while surviving for $\\gtrsim 3$ yr, the surface density of the disc needs to be within a certain range. For example, given a $1M_\\odot$ MS orbiter the surface density of the disc gas should be in the range of $3\\times10^5\\sim 2\\times10^6$g cm$^{-2}$ for GSN069 or $5\\times10^4\\sim 10^6$ g cm$^{-2}$ for eRO-QPE2. In both of these two sources, the MS can not survive for more than $\\sim 12$ yr. We expect that future observations of these two sources can help to distinguish whether the orbiters are degenerated compact objects or gaseous stars.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2025-05-05T12:04:48.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "x-ray quasi-periodic eruptions driven",
      "secular periodic evolution",
      "star-disc collisions",
      "surface density",
      "periodic decay"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 20,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}