The Effect of Primordial Non-Gaussianities on the Seeds of Super-Massive Black Holes

TL;DR

This paper investigates how primordial non-Gaussianities influence the formation of seeds for super-massive black holes, finding current observational bounds limit their impact compared to cosmic string loops.

Contribution

It provides an analysis of the effects of primordial non-Gaussianities on black hole seed formation within the standard cosmological model, highlighting their limited role.

Findings

Primordial non-Gaussianities constrained by current bounds do not significantly increase seed abundance.

Cosmic string loops may have a more substantial role in seeding super-massive black holes.

Standard Gaussian perturbations are insufficient to explain high-redshift SMBH seeds.

Abstract

The origin of the seeds which develop into the observed super-massive black holes at high redshifts may be hard to interpret in the context of the standard $\Lambda CDM$ of early universe cosmology based on Gaussian primordial perturbations. Here we consider the modification of the halo mass function obtained by introducing skewness and kurtosis of the primordial fluctuations. We show that such primordial non-Gaussianities constrained by the current observational bounds on the nonlinearity parameters of $f_{NL}$ and $g_{NL}$ are not effective at greatly increasing the number density of seeds which could develop into super-massive black holes at high redshifts. This is to be contrasted with the role which cosmic string loops could play in seeding super-massive black holes.