English

Peaks and primordial black holes: the effect of non-Gaussianity

Cosmology and Nongalactic Astrophysics 2023-10-26 v3

Abstract

In light of recent developments in the field, we re-evaluate the effect of local-type non-Gaussianity on the primordial black hole (PBH) abundance (and consequently, upon constraints on the primordial power spectrum arising from PBHs). We apply peaks theory to the full, non-linear compaction, finding that, whilst the effect of non-Gaussianity is qualitatively similar to previous findings, the effect is much less significant. It is found the non-Gaussianity parameters fNLlocalf_\mathrm{NL}^\mathrm{local} and gNLlocalg_\mathrm{NL}^\mathrm{local} typically need to be approximately 1 or 2 orders of magntiude larger respectively to have a similar to that previously found. The effect will be to weaken the dependance of PBH constraints on the primordial power spectrum on the non-Gaussianity parameters, as well as to dramatically weaken constraints on the non-Gaussianity parameters (and/or PBH abundance) arising from the non-observation of dark matter isocurvature modes. We also consider the correlation between the curvature perturbation ζ\zeta and the compaction CC, finding that, whilst PBHs may form at rare peaks in CC these do not necessarily correspond to rare peaks in ζ\zeta - casting some doubt on many of the existing calculations of the PBH abundance.

Keywords

Cite

@article{arxiv.2201.13345,
  title  = {Peaks and primordial black holes: the effect of non-Gaussianity},
  author = {Sam Young},
  journal= {arXiv preprint arXiv:2201.13345},
  year   = {2023}
}

Comments

18 pages, 3 figures (plus appendices: 4 pages, 2 figures). V2 and V3: updated to match published version, minor changes and corrections