Simulation of Primordial Black Holes with large negative non-Gaussianity

Abstract

In this work, we have performed numerical simulations of primordial black\nhole (PBH) formation in the Friedman-Lema\\^itre-Robertson-Walker universe\nfilled by radiation fluid, introducing the local-type non-Gaussianity to the\nprimordial curvature fluctuation. We have compared the numerical results from\nsimulations with previous analytical estimations on the threshold value for PBH\nformation done in the previous paper arXiv:2109.00791, particularly for\nnegative values of the non-linearity parameter $f_{\\rm NL}$. Our numerical\nresults show the existence of PBH formation of (the so-called) type I also in\nthe case $f_{\\rm NL} \\lesssim -0.336$, which was not found in the previous\nanalytical expectations using the critical averaged compaction function. In\nparticular, although the universal value for the averaged critical compaction\nfunction $\\bar{\\mathcal{C}}_{c}=2/5$ found previously in the literature is not\nsatisfied for all the profiles considered in this work, an alternative direct\nanalytical estimate has been found to be roughly accurate to estimate the\nthresholds, which gives the value of the critical averaged density with a few\n$\\%$ deviation from the numerical one for $f_{\\rm NL}\\gtrsim -1$.\n