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Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE,General Relativity and Quantum Cosmology, gr-qc
Abstract:
Sub-solar mass black hole binaries, due to their light mass, would have to be
primordial in origin instead of the result of stellar evolution. Soon after
formation in the early Universe, primordial black holes can form binaries after
decoupling from the cosmic expansion. Alternatively, primordial black holes as
dark matter could also form binaries in the late Universe due to dynamical
encounters and gravitational-wave braking. A significant feature for this
channel is the possibility that some sources retain non-zero eccentricity in
the LIGO/Virgo band. Assuming all dark matter is primordial black holes with a
delta function mass distribution, $1M_\odot-1M_\odot$ binaries formed in this
late Universe channel can be detected by Advanced LIGO and Virgo with at their
design sensitivities with a rate of $\mathcal{O}(1)$/year, where $12\%(3\%)$
events have eccentricity at gravitational-wave frequency 10 Hz,
$e^\mathrm{10Hz}\geq0.01(0.1)$, and non-detection can constrain the binary
formation rate within this model. Third generation detectors would be expected
to detect sub-solar mass eccentric binaries as light as $0.01 M_\odot$ within
this channel, if they account for the majority of the dark matter. Furthermore,
we use simulated gravitational-wave data to study the ability to search for
eccentric gravitational-wave signals using quasi-circular waveform template
bank with Advanced LIGO design sensitivity. Assuming binaries with a delta
function mass of $0.1(1)M_\odot$ and the eccentricity distribution derived from
this late Universe formation channel, for a match-filtering targeted search,
$41\%(6\%)$ of the signals would be missed compared to ideal detection rate due
to the mismatch in the gravitational-wave signal from eccentricity.
