Astrophys. J. 711, 517–531 (2010)

Mysterious radio signals could be coming from a large but quiet population in the Milky Way: old, slow-spinning neutron stars.

As many as one billion ancient neutron stars — the remnants of exploded stars — are thought to be scattered around the Galaxy, but only a tiny fraction can be easily detected. Eran Ofek at the California Institute of Technology in Pasadena and his colleagues follow up on the recent discovery of weak radiowave emissions, lasting hours to days, of unknown origin.

The researchers present infrared observations that rule out other objects — such as supernovae, quasars and pulsars — as sources. Old neutron stars offer insight into the Milky Way's history and, the authors suggest, would be easier to track down if they did prove to be the radio emitters.