Supermassive Primordial Black Holes From Inflation

Kavli Affiliate: Albert Stebbins

| First 5 Authors: Dan Hooper, Aurora Ireland, Gordan Krnjaic, Albert Stebbins,

| Summary:

There is controversy surrounding the origin and evolution of our universe’s
largest supermassive black holes (SMBHs). In this study, we consider the
possibility that some of these black holes formed from the direct collapse of
primordial density perturbations. Since the mass of a primordial black hole is
limited by the size of the cosmological horizon at the time of collapse, these
SMBHs must form rather late, and are naively in conflict with CMB spectral
distortion constraints. Such limits, however, can be avoided if the
distribution of primordial curvature perturbations is highly non-Gaussian. In
this study, we present a model of multi-field inflation — the curvaton model
supplemented with self-interactions — which can viably yield such dramatic
non-Gaussinities. Furthermore, we calculate the maximal abundance of black
holes that can be generated in this scenario and find this to be consistent
with the observed population of high-redshift SMBHs. This result is
particularly timely in light of recent evidence from the NANOGrav experiment
for a stochastic gravitational wave background consistent with SMBH mergers.

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