{
  "id": "1907.03034",
  "version": "v1",
  "published": "2019-07-05T22:22:39.000Z",
  "updated": "2019-07-05T22:22:39.000Z",
  "title": "Partial Stellar Disruption by a Supermassive Black Hole: Is the Lightcurve Really Proportional to $t^{-9/4}$?",
  "authors": [
    "Eric R. Coughlin",
    "C. J. Nixon"
  ],
  "comment": "7 pages, 2 figures, submitted to ApJL",
  "categories": [
    "astro-ph.GA",
    "astro-ph.HE"
  ],
  "abstract": "The tidal disruption of a star by a supermassive black hole, and the subsequent accretion of the disrupted debris by that black hole, offers a direct means to study the inner regions of otherwise-quiescent galaxies. These tidal disruption events (TDEs) are being discovered at an ever-increasing rate. We present a model for the evolution of the tidally-disrupted debris from a partial TDE, in which a stellar core survives the initial tidal encounter and continues to exert a gravitational influence on the expanding stream of tidally-stripped debris. We use this model to show that the asymptotic fallback rate of material to the black hole in a partial TDE scales as $\\propto t^{-2.26\\pm0.01}$, and is effectively independent of the mass of the core that survives the encounter; we also estimate the rate at which TDEs approach this asymptotic scaling as a function of the core mass. These findings suggest that the late-time accretion rate onto a black hole from a TDE either declines as $t^{-5/3}$ if the star is completely disrupted or $t^{-9/4}$ if a core is left behind. We emphasize that previous investigations have not recovered this result due to the assumption of a Keplerian energy-period relationship for the debris orbits, which is no longer valid when a surviving core generates a time-dependent, gravitational potential. This dichotomy of fallback rates has important implications for the characteristic signatures of TDEs in the current era of wide-field surveys.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-07-05T22:22:39.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "supermassive black hole",
      "partial stellar disruption",
      "lightcurve really proportional",
      "partial tde",
      "fallback rate"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}