Roman Space Telescope to Detect Hidden Neutron Stars via Microlensing

A study published in *Astronomy & Astrophysics* shows that NASA's upcoming Nancy Grace Roman Space Telescope could identify dozens of isolated neutron stars in the Milky Way. The telescope will use gravitational microlensing—monitoring the temporary brightening and tiny positional shift of background stars when a massive object passes in front—to detect objects that are otherwise invisible.

By measuring both photometric brightening and astrometric deflection with high precision, Roman can not only confirm the presence of a neutron star but also estimate its mass. This capability may reveal the mass distribution of neutron stars, clarify the gap between neutron‑star and black‑hole masses, and improve understanding of the high‑velocity "kicks" neutron stars receive at birth. The planned Galactic Bulge Time‑Domain Survey will monitor millions of stars, allowing researchers to start spotting promising events shortly after commissioning.

The findings suggest that, despite only a few thousand neutron stars having been detected so far (mostly as pulsars), the Roman telescope could dramatically expand the sample, providing new insights into stellar evolution, supernova mechanisms, and extreme matter physics.