UC Riverside

We explore the connection between supermassive black hole (SMBH) formation and self-interacting dark matter in the early universe. Observations reveal SMBHs with $\sim10^9~{\rm M}_\odot$ masses when the universe was only $6\%$ of its current age. Our scenario involves self-interacting dark matter halos undergoing gravothermal instability, forming seed black holes, to account for their existence. In particular, baryonic matter in protogalaxies accelerates halo evolution. We further examine the angular momentum dissipation and conditions for dynamical (general relativistic) instability. We also explore quantum instability in self-gravitating thermal systems, emphasizing quantum degeneracy pressure's role in black hole formation. Additionally, we study spike mass density distribution in a scalar field dark halo, considering self-interaction and relativistic Bondi accretion onto non-spinning black holes. For primordial black holes (PBHs) as dark matter, we compare merger rates of PBH binaries to extremely mass ratio inspirals into SMBHs, which are detectable with gravitational wave technology.