{
  "id": "2401.14091",
  "version": "v1",
  "published": "2024-01-25T11:12:21.000Z",
  "updated": "2024-01-25T11:12:21.000Z",
  "title": "Rapid evolution of the recurrence time in the repeating partial tidal disruption event eRASSt J045650.3-203750",
  "authors": [
    "Zhu Liu",
    "Taeho Ryu",
    "A. J. Goodwin",
    "A. Rau",
    "D. Homan",
    "M. Krumpe",
    "A. Merloni",
    "I. Grotova",
    "G. E. Anderson",
    "A. Malyali",
    "J. C. A. Miller-Jones"
  ],
  "comment": "12 pages, 5 figures, submitted to A&A",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "In this letter, we present the results from further X-ray and UV observations of the nuclear transient eRASSt J045650.3-203750 (hereafter J0456-20). We detected five repeating X-ray and UV flares from J0456-20, making it one of the most promising repeating partial tidal disruption event (pTDE) candidates. More importantly, we also found rapid changes in the recurrence time $T_\\text{recur}$ of the X-ray flares by modelling the long-term X-ray light curve of J0456-20. $T_\\text{recur}$ first decreased rapidly from about 300 days to around 230 days. It continued to decrease to around 190 days with an indication of a constant $T_\\text{recur}$ evidenced from the latest three cycles. Our hydrodynamic simulations suggest that, in the repeating pTDE scenario, such rapid evolution of $T_\\text{recur}$ could be reproduced if the original star is a $1~\\mathrm{M}_\\odot$ main-sequence star near the terminal age and loses nearly 80-90% of its mass during the initial encounter with a supermassive black hole (SMBH) of mass around $10^5~\\mathrm{M}_\\odot$. The inferred mass loss of 0.8-0.9 $\\mathrm{M}_\\odot$ is higher than the estimated value of around 0.12 $\\mathrm{M}_\\odot$ from observation, which could be explained if the radiation efficiency is low (i.e. $\\ll0.1$). Our results indicate that repeating pTDEs could be effective tools to explore the dynamics around supermassive black holes beyond our own Galaxy.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-01-25T11:12:21.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "repeating partial tidal disruption event",
      "tidal disruption event erasst j045650",
      "partial tidal disruption event erasst",
      "recurrence time",
      "rapid evolution"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}