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Title: Illuminating massive black holes with white dwarfs: orbital dynamics and high-energy transients from tidal interactions

White dwarfs (WDs) can be tidally disrupted only by massive black holes (MBHs) with masses less than ∼10{sup 5} M {sub ☉}. These tidal interactions feed material to the MBH well above its Eddington limit, with the potential to launch a relativistic jet. The corresponding beamed emission is a promising indication of an otherwise quiescent MBH of relatively low mass. We show that the mass transfer history, and thus the light curve, is quite different when the disruptive orbit is parabolic, eccentric, or circular. The mass lost each orbit exponentiates in the eccentric-orbit case, leading to the destruction of the WD after several tens of orbits. We examine the stellar dynamics of clusters surrounding MBHs to show that single-passage WD disruptions are substantially more common than repeating encounters. The 10{sup 49} erg s{sup –1} peak luminosity of these events makes them visible to cosmological distances. They may be detectible at rates of as many as tens per year by instruments like Swift. In fact, WD-disruption transients significantly outshine their main-sequence star counterparts and are the tidal interaction most likely to be detected arising from MBHs with masses less than 10{sup 5} M {sub ☉}. The detection or nondetection of suchmore » WD-disruption transients by Swift is, therefore, a powerful tool to constrain the lower end of the MBH mass function. The emerging ultralong gamma-ray burst class of events all have peak luminosities and durations reminiscent of WD disruptions, offering a hint that WD-disruption transients may already be present in existing data sets.« less
Authors:
; ;  [1] ;  [2] ;  [3]
  1. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
  2. Astronomy Department, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)
Publication Date:
OSTI Identifier:
22370523
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BLACK HOLES; COSMIC GAMMA BURSTS; DETECTION; EMISSION; GALAXY NUCLEI; INTERACTIONS; LUMINOSITY; MAIN SEQUENCE STARS; MASS TRANSFER; ORBITS; RELATIVISTIC RANGE; TRANSIENTS; VISIBLE RADIATION; WHITE DWARF STARS