Magnetic fields of the early universe created black holes ⚡ экспресс
A new post-inflationary mechanism is proposed for amplifying primordial curvature perturbations on small scales — a key condition for forming a significant number of primordial black holes. The amplification occurs during the kinetic dominance (stiff expansion) era and stems from the vector component of the electromagnetic energy-momentum tensor, tied to primordial magnetic fields. First-order vector metric perturbations remain roughly constant throughout kination, acting as a steady nonlinear source for second-order scalar perturbations. It is shown that the curvature perturbations induced by the vector mode are amplified near the infrared boundary of the kination regime and have a power spectrum P_R(k) ∝ k^{-5}. As a specific scenario, magnetic field generation via the Ratra mechanism is considered; calculations indicate that the resulting primordial black holes could account for a substantial fraction of dark matter.
Shortly after the Big Bang, magnetic fields acted like a spoon, stirring spacetime and creating eddies. These eddies turned into clumps that collapsed into black holes — primordial, born without stars. Stephen Hawking and others considered them a possible explanation for dark matter. New work shows that such holes could have arisen due to magnetic fields during the era of rapid expansion. The eddies accumulated energy until they collapsed in on themselves. Their total mass is comparable to all dark matter. And one such hole could weigh as much as a mountain but be the size of an atom — if it passed through a planet, no one would notice.
🎯 A primordial black hole can weigh as much as a mountain but be the size of an atom.