[OKC-CosmologyGravity] TODAY at 13.15: Presentation by Marit Sandstad on Primordial Black Holes; 132.028 (Nordita main/east building)

[Florian Kühnel]

Dear All,

Today at 13.15 we will have our Marit Sandstad talking about recent work (by her, Cornelius Rampf (ICG Portsmouth), and myself) on primordial black holes (see: http://arxiv.org/abs/1512.00488 ):

Speaker:
Marit Sandstad (Nordita)

Time:
13.15

Place:
132.028 (Nordita main/east building)

Title:
Effects of Critical Collapse on Primordial Black-Hole Mass Spectra

Abstract:
Particularities of the early-Universe physics — such as bumpy features in the inflationary power spectrum or phase transition — may lead to the production of primordial black holes. If the primordial black holes are sufficiently large, they can provide a dark-matter candidate, otherwise the effects of their evaporation can have very large observational signatures. Hence comparison between predictions and observational bounds for primordial black holes are of great interest in cosmology. Primordial black holes are generally thought to form when density perturbations that exceed a threshold value re-enter the horizon and collapse into a black hole. In a first approximation this is assumed to result in primordial black holes of horizon mass M_H. However, it has been known since the late nineties that the collapse obeys a critical scaling, M = k M_H ( delta - delta_c )^gamma, where delta and delta_c are the density contrast and its threshold value, respectively, and k and gamma are constants. The effects of this scaling has been considered negligible or degenerate with other effects in the literature. In this talk I will show the results of our recent re-analysis in the context of several models of primordial black-hole formation. Comparing these results to the current status of observational bounds, we argue that the critical collapse should be taken properly into account in any comparison of a particular model to observations.


See you there!

Florian



P.S.: As usual, there will be coffee afterwards.



____________________________________________
Dr. Florian Kühnel

Postdoctoral Researcher

The Oskar Klein Centre for Cosmoparticle Physics,
Department of Physics, Stockholm University,
AlbaNova, SE-106 91 Stockholm, Sweden
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