Cosmic String Loops Collapsing to Black Holes

Abstract

We examine the question of collapse of Turok's two-parameter family of cosmic strings. We first perform a classification of the strings according to the specific time(s) at which the minimal string size is reached during one period. We then obtain an exact analytical expression for the probability of collapse to black holes for the Turok strings. Our result has the same general behavior as previously obtained in the literature but we find, in addition, a numerical prefactor that changes the result by three orders of magnitude. Finally we show that our careful computation of the prefactor helps to understand the discrepancy between previously obtained results and, in particular, that for "large" values of Gµ, there may not even be a discrepancy. We also give a simple physical argument that can immediately rule out some of the previously obtained results. * Electronic address: rnh@fysik.ou.dk † Electronic address: inane@fysik.sdu.dk ‡ Electronic address: all@fysik.ou.dk

Cosmological Formation of (2 + 1)-Dimensional Soliton Structures in Models Possessing Potentials with Local Peaks

“…Thus, even inflaton fields could lead to a formation of solitons. This to be checked in similar models to avoid overproduction in the early Universe and possible subsequent production of primordial black holes [12,16,21].…”

“…Moreover, it might affect the following evolution of the Universe if its abundance is significant enough [13,14]. Collapse of domain walls and strings might lead to primordial black holes (PBHs) formation [15][16][17][18][19][20] or even clusters of PBHs [21,22] having a lot of astrophysical evidences. Whether primordial black holes could significantly contribute to dark matter is a widely-discussed question [23].…”

Primordial black hole formation with full numerical relativity

“…Various formation mechanisms could be relevant for PBHs [27,28]. These mechanisms include the formation of PBHs during inflation [29][30][31][32], the collision of bubbles that result from first order phase transitions [33][34][35][36][37][38][39][40][41][42], the collapse of cosmic strings [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60], the collapse of domain walls produced during a second order phase transition [61][62][63][64][65][66], the collapse of a scalar condensate in the early universe [67][68][69][70] and specific baryogenesis scenarios [71][72][73][74]…”

Comment on “Formation of primordial black holes by cosmic strings”

“…On the other hand, for some other particular examples, it seemed that the conclusions (2)-(3) were indeed correct. Thus to clarify the situation, we did a complete re-analysis of the problem (see [4] for the details) using both analytical and numerical methods. This led to a precise classification of the Turok-strings, and a subsequent subdivision into 3 different families (see Fig.…”

“…This is the most relevant region for string collapse since it includes the circular string (α = β = 0), and string collapse is only to be expected for low angular momentum near-circular strings. In any case, in the region I, it is easy to derive the exact analytical expression for the minimal string size [4]:…”