Detectable radio flares following gravitational waves from mergers of binary neutron stars

Compact binary mergers are the main sources targeted by ground-based gravitational wave detectors. Numerical simulations suggest that these mergers eject energetic sub-relativistic — or even relativistic — outflows. The interaction of such outflows with the surrounding interstellar medium would create a long-lasting radio signal. Ehud Nakar and Tsvi Piran report calculations showing that mildly relativistic outflows would produce radio flares with peak emission at 1.4 gigahertz that persist at detectable levels for weeks, out to a redshift of 0.1. The radio transient RT 19870422 has the properties predicted by their model and its most probable origin is a compact binary merger.