Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultraluminous X-ray Sources as Intermediate Mass Black Holes Fed by
  Tidally Captured Stars   The nature of ultraluminous X-ray sources (ULXs) is presently unknown. A
possible explanation is that they are accreting intermediate mass black holes
(IBHs) that are fed by Roche lobe overflow from a tidally captured stellar
companion. We show that a star can circularize around an IBH without being
destroyed by tidal heating (in contrast to the case of M_bh> 10^6 M_sun massive
black holes in galactic centers, where survival is unlikely). We find that the
capture and circularization rate is of the order of 5 \times 10^-8 yr^-1,
almost independently of the cluster's relaxation time. We follow the luminosity
evolution of the binary system during the main sequence Roche lobe overflow
phase and show it can maintain ULX-like luminosities for >10 Myr. In
particular, we show that the ULX in the young cluster MGG-11 in star-burst
galaxy M82, which possibly harbors an IBH, is well explained by this mechanism,
and we predict that \gtrsim 10% of similar clusters with IBHs have a tidally
captured circularized star. The cluster can evaporate on a time-scale shorter
than the lifetime of the binary. This raises the possibility of a ULX that
outlives its host cluster, or even lights up only after the cluster has
evaporated, in agreement with observations of host-less ULXs.

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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: math
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The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: cond-mat
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The categories of this paper are: physics
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The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: hep-lat