Tidal Disruption of a Main-Sequence Star by an Intermediate-Mass Black
Hole: A Bright Decade
release_oos4bexe7rd2rp3yit2kcvshiu
by
Jin-Hong Chen
2018
Abstract
There has been suggestive evidence of intermediate-mass black holes (IMBHs;
10^3-5 M_sun) existing in some globular clusters (GCs) and dwarf galaxies,
but IMBHs as a population remain elusive. As a main-sequence star passes too
close by an IMBH it might be tidally captured and disrupted. We study the
long-term accretion and observational consequence of such tidal disruption
events. The disruption radius is hundreds to thousands of the BH's
Schwarzschild radius, so the circularization of the falling-back debris stream
is very inefficient due to weak general relativity effects. Due to this and a
high mass fallback rate, the bound debris initially goes through a 10 yr long
super-Eddington accretion phase. The photospheric emission of the outflow
ejected during this phase dominates the observable radiation and peaks in the
UV/optical bands with a luminosity of 10^42 erg/s. After the accretion rate
drops below the Eddington rate, the bolometric luminosity follows the
conventional t^-5/3 power-law decay, and X-rays from the inner accretion disk
start to be seen. Modeling the newly reported IMBH tidal disruption event
candidate 3XMM J2150-0551, we find a general consistency between the data and
predictions. The search for these luminous, long-term events in GCs and nearby
dwarf galaxies could unveil the IMBH population.
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