Neutron stars are basically giant traps for dark matter, which keeps them weirdly warm long after they should’ve cooled down.
arXiv · March 13, 2026 · 2603.11458
Why it matters
Researchers found that the extreme conditions of a supernova produce dark matter that gets caught in the star's gravity. These trapped particles eventually collide and release energy, potentially creating a heat source that astronomers could use to finally 'see' dark matter by looking for stars that refuse to cool.
From the abstract
Every neutron star is born in the process of core-collapse supernova explosion that, for a brief moment, reproduces conditions of the early Universe with temperatures $T\sim O(30\rm\,MeV)$. We calculate the production of Dark Matter $\chi$ from the SM particles in such events, SM $\to\chi\bar\chi$, for the freeze-in range of couplings, $\alpha_{\rm FI} \sim O(10^{-26}) $, finding that $O(10^{-6})$ $\chi$'s per nucleon is produced. The strong gravitational potential well of the neutron star retai