Kavli Affiliate: Gordan Krnjaic
| 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 constraints from
CMB spectral distortions. These limits can be avoided, however, if the
distribution of primordial curvature perturbations is highly non-Gaussian.
After quantifying the departure from Gaussianity needed to evade these bounds,
we explore a model of multi-field inflation — a non-minimal, self-interacting
curvaton model — which has all the necessary ingredients to yield such
dramatic non-Gaussianities. We leave the detailed model building and numerics
to a future study, however, as our goal is to highlight the challenges
associated with forming SMBHs from direct collapse and to identify features
that a successful model would need to have. This study is particularly timely
in light of recent observations of high-redshift massive galaxy candidates by
the James Webb Space Telescope as well as evidence from the NANOGrav experiment
for a stochastic gravitational wave background consistent with SMBH mergers.
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