Primordial Black Holes Formed during Magneto-Hydrodynamic Turbulence in Early Universe as Dominant Part of Dark Matter

Abstract: Primordial black holes (PBH) offer a compelling candidate for dark matter. Within the framework of the Standard Model, the production of PBHs through well-tested physical processes is highly worthy of investigations. This work highlights the role of turbulences in the very early universe in sustaining intense and persistent fluctuations of energy or mass density, which could provide a natural mechanism for PBH formations in the primordial universe. We analyze the mass range and abundance of PBHs produced in the magnetohydrodynamic turbulence induced by the first-order electroweak phase transition. Remarkably, without invoking any new physics beyond the Standard Model, we find that the mass range of the produced PBHs falls within the only allowed "asteroid mass" window, and within natural parameter regions their abundance can be sufficiently large. These findings strongly suggest that PBHs produced in the magnetohydrodynamic turbulence in the early universe could comprise the dominant part of dark matter.