Primordial black holes do not (yet) constrain the primordial power spectrum [CEA]

http://arxiv.org/abs/1611.10069


Primordial black holes (PBHs) are thought to have formed from extremely overdense regions that reentered the horizon after the end of inflation if there was sufficient power in primordial perturbations on specific scales. The existence (and abundance) of PBHs is therefore governed by the inflationary power spectrum. So far no primordial black holes have been observed, and instead, increasingly stringent bounds on their existence at different scales have been set. Up until recently this has been exploited in attempts to constrain parts of the inflationary power spectrum that are unconstrained by the cosmic microwave background and other cosmological observations. In this letter we point out that this simple translation of the PBH constraints into constraints on the primordial power spectrum is inaccurate as it fails to take into account realistic aspects of the PBH formation and evolution process. We show this by displaying a concrete example of a power spectrum that is seemingly in conflict with the constraints imposed on the power spectrum, but, when subjected to the well-studied critical-collapse effect, leads to a mass spectrum which is allowed by the PBH non-observations used to constrain the same power spectrum.

Read this paper on arXiv…

Y. Akrami, F. Kuhnel and M. Sandstad
Thu, 1 Dec 16
2/75

Comments: 4 pages, 1 figure