Catastrogenesis: DM, GWs, and PBHs from ALP string-wall networks

Abstract

Axion-like particles (ALPs), a compelling candidate for dark matter (DM), are the pseudo Nambu-Goldstone bosons of a spontaneously and explicitly broken global U(1) symmetry. When the symmetry breaking happens after inflation, the ALP cosmology predicts the formation of a string-wall network which must annihilate early enough, producing gravitational waves (GWs) and primordial black holes (PBHs), as well as non-relativistic ALPs. We call this process catastrogenesis. We show that, under the generic assumption that the potential has several degenerate minima, GWs from string-wall annihilation at temperatures below 100 eV could be detected by future CMB and astrometry probes, for ALPs with mass from 10-16 to 106 eV. In this case, structure formation could limit ALPs to constitute a fraction of the DM and the annihilation would produce mostly “stupendously large” PBHs. For larger annihilation temperatures, ALPs can constitute 100% of DM, and the annihilation could produce supermassive black holes with a mass of up to 109 M ⊙ as found at the center of large galaxies. Therefore our model can solve two mysteries, the nature of the DM and the origin of these black holes.

Primordial black hole dark matter from catastrogenesis with unstable pseudo-Goldstone bosons

“…[6,[19][20][21]), bubble collisions [22,23], the collapse of cosmic strings [24], scalar field dynamics [25][26][27][28], long-range interactions [29], and collapse of domain walls [30,31] or vacuum bubbles [32,33] in multi-field inflationary scenarios. We propose here a novel production scenario for asteroid-mass PBHs based on the mechanism we have dubbed catastrogenesis in our previous work [34]. Our mechanism does not depend on inflationary physics, nor on primordial density perturbations, and crucially it can be linked to other unsolved problems in particle physics, e.g.…”

“…Majorons could decay mostly into two relatively heavy right-handed neutrinos, which in turn decay very fast into pions, charged fermion pairs, and active neutrinos. Therefore, such pGBs cannot be the DM in the models we consider, but catastrogenesis [34] may lead to a different DM candidate, namely PBHs. We consider explicit breaking potentials which admit a number N > 1 of minima along the orbit of vacua.…”

“…The cosmological problem is solved by adding an additional explicit breaking in the Lagrangian [81][82][83], possibly due to the effect of Planck suppressed operators [34,84,85], which produces an energy difference (a bias) between the minima that leads to a unique vacuum. As first proposed in 1974 in ref.…”

V.2.5 Gelegenheitsgedichte

“…Note that string-wall networks with N > 1 can have spherically collapsing closed walls leading to the formation of potentially over-abundant primordial black holes (PBH) [207][208][209]. Reference [210] points out that more numerical simulations are needed in order to conclusively treat this effect and further mentions that the presence of angular momentum could lead to a sufficient deviation from the spherical symmetry impeding the PBH formation. Since here the rotating Diraxion background constitutes a source of angular momentum.…”

Primordial black holes from D-parity breaking in SO(10) grand unified theory

“…They may play an important role in the generation of cosmological structures. The PBH formation scenarios rely on the collapse of inhomogeneities [14] which has been more recently treated in [15], while PBH formation from the collapse of topological defects has also been proposed (see for instance [16,17]). In this paper we study the formation of PBHs from the collapse of topological pseudo-defect domain walls that form in the course of spontaneous gauge symmetry breaking phase transition.…”