Merging massive black holes: the right place and the right time

TL;DR

This paper investigates the origins of merging black holes detected by LIGO/Virgo, linking their formation to galaxy properties and evolution, and uses simulations to understand their black hole populations.

Contribution

It combines galaxy formation models with binary population synthesis to predict black hole merger rates and explores galaxy types influencing black hole progenitors.

Findings

Merger signals mainly originate from massive galaxies at star formation peaks.

Recent dwarf galaxy star formation also contributes significantly.

Hydrodynamic simulations provide insights into black hole populations in different galaxy types.

Abstract

The LIGO/Virgo detections of gravitational waves from merging black holes of $\simeq$ 30 solar mass suggest progenitor stars of low metallicity (Z/Z$_{\odot} \lesssim 0.3$). In this talk I will provide constrains on where the progenitors of GW150914 and GW170104 may have formed, based on advanced models of galaxy formation and evolution combined with binary population synthesis models. First I will combine estimates of galaxy properties (star-forming gas metallicity, star formation rate and merger rate) across cosmic time to predict the low redshift BBH merger rate as a function of present day host galaxy mass, formation redshift of the progenitor system and different progenitor metallicities. I will show that the signal is dominated by binaries formed at the peak of star formation in massive galaxies with and binaries formed recently in dwarf galaxies. Then, I will present what very high resolution hydrodynamic simulations of different galaxy types can learn us about their black hole populations.