Binary black holes in the pair-instability mass gap. (arXiv:1911.01434v1 [astro-ph.HE])

Binary black holes in the pair-instability mass gap. (arXiv:1911.01434v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Carlo_U/0/1/0/all/0/1">Ugo N. Di Carlo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mapelli_M/0/1/0/all/0/1">Michela Mapelli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bouffanais_Y/0/1/0/all/0/1">Yann Bouffanais</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Giacobbo_N/0/1/0/all/0/1">Nicola Giacobbo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bressan_S/0/1/0/all/0/1">Sandro Bressan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spera_M/0/1/0/all/0/1">Mario Spera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Haardt_F/0/1/0/all/0/1">Francesco Haardt</a>

Pair instability (PI) and pulsational PI prevent the formation of black holes
(BHs) with mass $gtrsim{}60$ M$_odot$ from single star evolution. Here, we
investigate the possibility that BHs with mass in the PI gap form via stellar
mergers and multiple stellar mergers, facilitated by dynamical encounters in
young star clusters. We ran 6000 simulations with the direct N-body code
NBODY6++GPU coupled with the population synthesis code MOBSE. We find that up
to $sim{}5$% of all simulated BHs have mass in the PI gap, depending on
progenitor’s metallicity (this formation channel is more efficient in
metal-poor star clusters). BHs with mass in the PI gap are initially single BHs
but can efficiently acquire companions through dynamical exchanges. We find
that up to $sim{}2$% of all binary BH (BBH) mergers have at least one
component in the PI mass gap. We predict that up to $sim{}9$% of all BBHs
detectable by advanced LIGO and Virgo at their design sensitivity have at least
one component in the PI mass gap.

Pair instability (PI) and pulsational PI prevent the formation of black holes
(BHs) with mass $gtrsim{}60$ M$_odot$ from single star evolution. Here, we
investigate the possibility that BHs with mass in the PI gap form via stellar
mergers and multiple stellar mergers, facilitated by dynamical encounters in
young star clusters. We ran 6000 simulations with the direct N-body code
NBODY6++GPU coupled with the population synthesis code MOBSE. We find that up
to $sim{}5$% of all simulated BHs have mass in the PI gap, depending on
progenitor’s metallicity (this formation channel is more efficient in
metal-poor star clusters). BHs with mass in the PI gap are initially single BHs
but can efficiently acquire companions through dynamical exchanges. We find
that up to $sim{}2$% of all binary BH (BBH) mergers have at least one
component in the PI mass gap. We predict that up to $sim{}9$% of all BBHs
detectable by advanced LIGO and Virgo at their design sensitivity have at least
one component in the PI mass gap.

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