Escape speed of stellar clusters from multiple-generation black-hole mergers in the upper mass gap. (arXiv:1906.05295v1 [astro-ph.HE])

Escape speed of stellar clusters from multiple-generation black-hole mergers in the upper mass gap. (arXiv:1906.05295v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gerosa_D/0/1/0/all/0/1">Davide Gerosa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Berti_E/0/1/0/all/0/1">Emanuele Berti</a>

Pair instabilities in supernovae might prevent the formation of black holes
with masses between ~50 $M_odot$ and ~130 $M_odot$. Multiple generations of
black-hole mergers provide a possible way to populate this “mass gap” from
below. However this requires an astrophysical environment with a sufficiently
large escape speed to retain merger remnants, and prevent them from being
ejected by gravitational-wave recoils. We show that, if the mass gap is indeed
populated by multiple mergers, the observation of a single black-hole binary
component in the mass gap implies that its progenitors grew in an environment
with escape speed $v_{rm esc} gtrsim 50$ km/s. This is larger than the escape
speeds of most globular clusters, requiring denser and heavier environments
such as nuclear star clusters or disks-assisted migration in galactic nuclei.

Pair instabilities in supernovae might prevent the formation of black holes
with masses between ~50 $M_odot$ and ~130 $M_odot$. Multiple generations of
black-hole mergers provide a possible way to populate this “mass gap” from
below. However this requires an astrophysical environment with a sufficiently
large escape speed to retain merger remnants, and prevent them from being
ejected by gravitational-wave recoils. We show that, if the mass gap is indeed
populated by multiple mergers, the observation of a single black-hole binary
component in the mass gap implies that its progenitors grew in an environment
with escape speed $v_{rm esc} gtrsim 50$ km/s. This is larger than the escape
speeds of most globular clusters, requiring denser and heavier environments
such as nuclear star clusters or disks-assisted migration in galactic nuclei.

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