Gravitational-wave sources from mergers of binary black-holes catalyzed by fly-bys interactions in the field. (arXiv:1902.01864v1 [astro-ph.SR])

Gravitational-wave sources from mergers of binary black-holes catalyzed by fly-bys interactions in the field. (arXiv:1902.01864v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Michaely_E/0/1/0/all/0/1">Erez Michaely</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Perets_H/0/1/0/all/0/1">Hagai B. Perets</a>

Several scenarios were suggested for the origins of gravitational-wave (GW)
sources from mergers of stellar binary black holes (BBHs). Here we propose a
novel origin through catalyzed formation of GW-sources from ultra-wide binaries
in the field. Such binaries experience perturbations from random stellar
fly-bys which excite their eccentricities. Once a wide-binary is driven to a
sufficiently small peri-center approach, GW-emission becomes significant, and
the binary inspirals and merges. We derive an analytic model and verify it with
numerical calculation to compute the merger rate to be $sim10{rm times
f_{wide},{rm Gpc}^{-3}yr^{-1}}$ ($f_{{rm wide}}$ is the fraction of wide
BH-binaries), which is comparable to the observationally inferred rate. The
observational signatures from this channel include spin-orbit misalignment;
preference for high mass-ratio BBH; preference for high velocity-dispersion
host-galaxies; and a uniform delay-time distribution.

Several scenarios were suggested for the origins of gravitational-wave (GW)
sources from mergers of stellar binary black holes (BBHs). Here we propose a
novel origin through catalyzed formation of GW-sources from ultra-wide binaries
in the field. Such binaries experience perturbations from random stellar
fly-bys which excite their eccentricities. Once a wide-binary is driven to a
sufficiently small peri-center approach, GW-emission becomes significant, and
the binary inspirals and merges. We derive an analytic model and verify it with
numerical calculation to compute the merger rate to be $sim10{rm times
f_{wide},{rm Gpc}^{-3}yr^{-1}}$ ($f_{{rm wide}}$ is the fraction of wide
BH-binaries), which is comparable to the observationally inferred rate. The
observational signatures from this channel include spin-orbit misalignment;
preference for high mass-ratio BBH; preference for high velocity-dispersion
host-galaxies; and a uniform delay-time distribution.

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