Physics Nature Is Weird

Some neutron stars might be hiding a secret core of dark matter, which would explain why they’re so impossibly huge.

March 25, 2026

Original Paper

Analyzing Fermionic Dark Matter scenarios with anomalous compact objects

Yaiza Cano, Jose Manuel Alarcón

arXiv · 2603.22490

The Takeaway

Scientists found that 'anomalous' compact objects in space that don't fit current physics models can be perfectly explained if they contain a small amount of dark matter. This means dark matter isn't just a ghost-like substance in the void, but can actively cluster inside stars and change how they behave.

From the abstract

In this paper, we consider three compact objects (HESS J1731-347, PSR J1231-1411, XTE J1814-338) with anomalous mass-radius relation to analyze the possibility of being dark matter admixed neutron stars. We try to infer the dark matter particle properties, under the assumption of behaving as a free Fermi gas. The main novelty relies on the use of a baryonic equation of state obtained from first principles in the whole density range, that allows to eliminate the model dependence of the baryonic p