Gravitational Waves from Black Holes in Merging Ultra-Dwarf Galaxies

Understand

The origin of the black-hole:black-hole mergers discovered through gravitational waves with for example the LIGO/Virgo collaboration are a mystery.

• We investigate the idea that some of these black holes originate from the centers of extremely low-mass ultra-dwarf galaxies that have merged together in the distant past at $z>1$.
• Extrapolating the central black hole to stellar mass ratio suggests that the black holes in these mergers could arise from galaxies of masses $\sim 10^{5} - 10^{6}$ M$_{\odot}\,$.
• We investigate whether these galaxies merge enough, or too much, to be consistent with the observed GW rate of $\sim 9.7-101$ Gpc$^{-3}$ yr$^{-1}$ using the latest LIGO/Virgo results.