Some of the heaviest, densest objects in the universe might have popped into existence at the very start of time, way before the first star was even born.
April 13, 2026
Original Paper
Primordial Neutron Stars
arXiv · 2604.08651
The Takeaway
We used to think neutron stars were just the "corpses" left behind when giant stars die. This theory suggests they could be primordial fossils from the Big Bang itself, rewriting the history of how matter formed.
From the abstract
We propose a novel cosmological scenario in which baryonic neutron stars could plausibly form in the early universe. If baryogenesis initially produces an excessively-large baryon asymmetry, $Y_B \gg 10^{-10},$ the baryonic mass inside the horizon can exceed the minimum neutron star mass before big bang nucleosynthesis (BBN). While this large asymmetry is present, non-relativistic baryons can dominate the universe and enhanced density perturbations on small scales can gravitationally collapse Hu