# Non-Gaussian Formation of Primordial Black Holes: Effects on the Threshold

## TL;DR

This paper studies how intrinsic non-Gaussianity affects the formation threshold of primordial black holes, finding that the threshold is relatively robust against non-linearities and small non-Gaussian effects.

## Contribution

It provides a detailed analysis of the impact of non-Gaussianity on the critical threshold for primordial black hole formation, showing minimal effect from non-linearities.

## Key findings

- The threshold $\delta_c$ changes by a few percent due to non-Gaussianity.
- The threshold remains robust against small local primordial non-Gaussianity.
- Non-linear relations introduce minor corrections to black hole formation criteria.

## Abstract

Primordial black holes could have been formed in the early universe from sufficiently large cosmological perturbations re-entering the horizon when the Universe is still radiation dominated. These originate from the spectrum of curvature perturbations generated during inflation at small-scales. Because of the non-linear relation between the curvature perturbation $\zeta$ and the overdensity $\delta\rho$, the formation of the primordial black holes is affected by intrinsic non-Gaussianity even though the curvature perturbation is Gaussian. We investigate the impact of this non-Gaussianity on the critical threshold $\delta_c$ which measures the excess of mass of the perturbation, finding a relative change with respect to the value obtained using a linear relation between $\zeta$ and $\delta\rho$, of a few percent. This shows that the value of the critical threshold is rather robust against non-linearities. The same holds also when cosmologically interesting values of local primordial non-Gaussianity are added to the curvature perturbation.