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要旨

We present the first search for gravitational waves from sub-solar mass
compact-binary mergers which allows for non-negligible orbital eccentricity.
Sub-solar mass black holes are a signature of primordial origin black holes,
which may be a component of dark matter. To produce binary coalescences,
primordial black holes may form close binaries either in the early universe or
more recently through dynamical interactions. A signature of dynamical
formation would be the observation of non-circularized orbits. We search for
black hole mergers where the primary mass is $0.1-7 M_{\odot}$ and the
secondary mass is $0.1-1 M_{\odot}$. We allow for eccentricity up to $\sim0.3$
at a dominant-mode gravitational-wave frequency of 10 Hz for binaries with at
least one component with mass $>0.5 M_{\odot}$. We find no convincing
candidates in the public LIGO data. The two most promising candidates have a
false alarm rate of 1 per 3 and 4 years, respectively, which combined is only a
$\sim 2.4\sigma$ deviation from the expected Poisson rate. Given the marginal
statistical significance, we place upper limits on the rate of sub-solar mass
mergers under the assumption of a null observation and compare how these limits
may inform the possible dark matter contribution.