Axion and the Supermassive Black Holes at high $z$

TL;DR

This paper explores how ultra-light axion dark matter could explain the early formation of supermassive black holes at high redshift and potentially account for observed nano-Hz gravitational waves.

Contribution

It introduces the idea that axion dark matter's self-interactions can resolve the angular momentum and formation timing issues of SMBHs.

Findings

Axion DM's self-interaction may facilitate early SMBH formation.

Ultra-light axion around 10^{-21} eV could generate nano-Hz gravitational waves.

The model links dark matter properties with gravitational wave observations.

Abstract

Axion dark matter (DM) is studied on the formation of supermassive black holes (SMBHs) at high red shift $z$. It is shown that the attractive self interaction of this DM may solve the tension between the high angular momentum of SMBH and its early time formation. We consider the ultra-light axion DM around $O(10^{-21})$ eV as its origin, which may also cause nano-Hz stochastic gravitational wave background recently observed.