Related papers: A universal threshold for primordial black hole fo…
We show why the threshold for primordial black hole formation is universal (independent from the shape of the perturbation) when expressed in terms of the volume averaged compaction function. The proof is rooted in the self-similarity of…
We consider black holes which form from an initially spherically symmetric super-Hubble perturbation of a cosmological background filled by a perfect fluid $p=w \rho$ with $w\in (0,1]$. Previous work has shown that when $w = 1/3$…
Primordial black holes may have formed in the radiative era of the early Universe from the collapse of large enough amplitude perturbations of the metric. These correspond to non linear energy density perturbations characterized by an…
Primordial black holes could have been formed in the early universe from non linear cosmological perturbations re-entering the cosmological horizon when the Universe was still radiation dominated. Starting from the shape of the power…
First results of a numerical investigation of primordial black hole formation in the radiation dominated phase of the Early Universe are presented. The simulations follow the gravitational collapse of three different families of…
We numerically simulate the formation of Primordial Black Holes (PBHs) in a radiation-dominated Universe under the assumption of spherical symmetry, driven by the collapse of adiabatic fluctuations, for different curvature profiles $\zeta$.…
We consider the formation of primordial black holes (PBHs), during the radiation-dominated Universe, generated from the collapse of super-horizon curvature fluctuations that are overlapped with others on larger scales. Using a set of…
We show that the abundance of primordial black holes, if formed through the collapse of large fluctuations generated during inflation and unless the power spectrum of the curvature perturbation is very peaked, is always dominated by the…
We provide evidence for a correspondence between the formation of black holes and the stability of circular null geodesics around the collapsing perturbation. We first show that the critical threshold of the compaction function to form a…
Based on a physical argument, we derive a new analytic formula for the amplitude of density perturbation at the threshold of primordial black hole formation in the universe dominated by a perfect fluid with the equation of state $p=w\rho…
We show that the threshold to form a black hole, in an asymptotically flat and radiation-dominated Friedman-Robertson-Walker (FRW) Universe, is not solely (mainly) determined by the behaviour of the compaction function at its extrema, as…
In this work, we have performed numerical simulations of primordial black hole (PBH) formation in the Friedman-Lema\^itre-Robertson-Walker universe filled by radiation fluid, introducing the local-type non-Gaussianity to the primordial…
We propose a geometrical origin for the Shibata-Sasaki compaction function, which is known to be a reliable indicator of primordial black hole formation at least during radiation domination. In the long-wavelength limit, we identify it with…
We study formation of black holes in the Friedmann universe. We present a formulation of the Einstein equations under the constant mean curvature time-slicing condition. Our formalism not only gives us the analytic solution of the…
Shibata and Sasaki [arXiv:gr-qc/9905064] introduced the so-called compaction function. Since then, it has been empirically established that the maximum value of this function (or its volume-averaged counterpart) in the long-wavelength…
Supersymmetric extensions of the standard model generically predict that in the early universe a scalar condensate can form and fragment into Q-balls before decaying. If the Q-balls dominate the energy density for some period of time, the…
Primordial black holes (PBHs) can form in the early Universe via the collapse of large density perturbations. There are tight constraints on the abundance of PBHs formed due to their gravitational effects and the consequences of their…
Within the framework that primordial black holes are formed by the direct gravitational collapse of large primordial density perturbations in the radiation dominated stage, we derive the threshold of the density contrast for the formation…
A common mechanism to form primordial black holes in the early universe is by enhancing at small-scales the scalar perturbations generated during inflation. If these fluctuations have a large enough amplitude, they may collapse into…
In certain two-dimensional models, collapsing matter forms a black hole if and only if the incoming energy flux exceeds the Hawking radiation rate. Near the critical threshold, the black hole mass is given by a universal formula in terms of…