Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SDSSJ092712.65+294344.0: a candidate massive black hole binary   In this Letter we explore the hypothesis that the quasar
SDSSJ092712.65+294344.0 is hosting a massive black hole binary embedded in a
circumbinary disc. The lightest, secondary black hole is active, and gas
orbiting around it is responsible for the blue-shifted broad emission lines
with velocity off-set of 2650 km/s, relative to the galaxy rest frame. As the
tidal interaction of the binary with the outer disc is expected to excavate a
gap, the blue-shifted narrow emission lines are consistent with being emitted
from the low-density inhomogeneous gas of the hollow region. From the
observations we infer a binary mass ratio q ~ 0.3, a mass for the primary of M1
~ 2 billion Msun and a semi-major axis of 0.34 pc, corresponding to an orbital
period of 370 years. We use the results of cosmological merger trees to
estimate the likely-hood of observing SDSSJ092712.65+294344.0 as recoiling
black hole or as a binary. We find that the binary hypothesis is preferred
being one hundred times more probable than the ejection hypothesis. If
SDSSJ092712.65+294344.0 hosts a binary, it would be the one closest massive
black hole binary system ever discovered.

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The categories of this paper are: cond-mat
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The categories of this paper are: math-ph
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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: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: q-bio
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The categories of this paper are: math