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The University of Southampton
STAG Research Centre

Gravity seminar - Davide Gerosa Seminar

20 February 2020
Building 54, room 7033 (7C)

For more information regarding this seminar, please email Oscar Dias at .

Event details

Title: Multiple generations of black-hole mergers to pinpoint their astrophysical origin

Abstract: Pair instabilities in supernovae might prevent the formation of black holes with masses between ∼50 and ∼130 solar masses. 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 a single LIGO/Virgo observation of a black hole in the pair-instability mass gap implies that its progenitors grew in an environment with escape speed >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. A single detection in the mass gap would also hint at the existence of a much larger population of first-generation events from the same environment, thus providing a tool to disentangle the contribution of different formation channels to the observed merger rate. Furthermore, we predict this population of higher generation black holes to have a distinctive spin distribution that will allow solid identification.

Speaker information

Davide Gerosa, Birmingham.

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