TY - JOUR
T1 - Hierarchical binary black hole mergers in globular clusters
T2 - Mass function and evolution with redshift
AU - Torniamenti, Stefano
AU - Mapelli, Michela
AU - Périgois, Carole
AU - Arca Sedda, Manuel
AU - Artale, Maria Celeste
AU - Dall'Amico, Marco
AU - Vaccaro, Maria Paola
N1 - Publisher Copyright:
© The Authors 2024.
PY - 2024/8/1
Y1 - 2024/8/1
N2 - Hierarchical black hole (BH) mergers are one of the most straightforward mechanisms producing BHs inside and above the pair-instability mass gap. We investigated the impact of globular cluster (GC) evolution on hierarchical mergers, accounting for the uncertainties related to BH mass pairing functions on the predicted primary BH mass, mass ratio, and spin distribution. We find that the evolution of the host GC quenches the hierarchical BH assembly at the third generation, mainly due to cluster expansion powered by a central BH subsystem. Hierarchical mergers match the primary BH mass distribution from GW events for m1 > 50 M⊙ regardless of the assumed BH pairing function. At lower masses, however, different pairing functions lead to dramatically different predictions on the primary BH mass merger-rate density. We find that the primary BH mass distribution evolves with redshift, with a larger contribution from mergers with m1 ≥30 M⊙ for z ≥2. Finally, we calculate the mixing fraction of binary black holes (BBHs) from GCs and isolated binary systems. Our predictions are very sensitive to the spins, which favor a large fraction (> 0.6) of BBHs born in GCs in order to reproduce misaligned spin observations.
AB - Hierarchical black hole (BH) mergers are one of the most straightforward mechanisms producing BHs inside and above the pair-instability mass gap. We investigated the impact of globular cluster (GC) evolution on hierarchical mergers, accounting for the uncertainties related to BH mass pairing functions on the predicted primary BH mass, mass ratio, and spin distribution. We find that the evolution of the host GC quenches the hierarchical BH assembly at the third generation, mainly due to cluster expansion powered by a central BH subsystem. Hierarchical mergers match the primary BH mass distribution from GW events for m1 > 50 M⊙ regardless of the assumed BH pairing function. At lower masses, however, different pairing functions lead to dramatically different predictions on the primary BH mass merger-rate density. We find that the primary BH mass distribution evolves with redshift, with a larger contribution from mergers with m1 ≥30 M⊙ for z ≥2. Finally, we calculate the mixing fraction of binary black holes (BBHs) from GCs and isolated binary systems. Our predictions are very sensitive to the spins, which favor a large fraction (> 0.6) of BBHs born in GCs in order to reproduce misaligned spin observations.
KW - Black hole physics
KW - Galaxies: star clusters: general
KW - Gravitational waves
KW - Stars: black holes
KW - Stars: kinematics and dynamics
UR - http://www.scopus.com/inward/record.url?scp=85201714059&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202449272
DO - 10.1051/0004-6361/202449272
M3 - Article
AN - SCOPUS:85201714059
SN - 0004-6361
VL - 688
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A148
ER -