Astro2020 Science White Paper: Radio Counterparts of Compact Object Mergers in the Era of Gravitational-Wave Astronomy

TL;DR

Enhancing GHz radio arrays to be ten times more sensitive will significantly advance multi-messenger astrophysics by enabling detailed studies of neutron star merger ejecta and progenitors alongside gravitational wave observations.

Contribution

This paper advocates for next-generation GHz radio arrays with 10x improved sensitivity to unlock new scientific opportunities in multi-messenger astrophysics.

Findings

Next-generation GHz radio arrays can probe relativistic jets and ejecta in neutron star mergers.

Improved radio sensitivity will enable detailed host galaxy studies of merger progenitors.

Enhanced arrays will complement gravitational wave detectors in the era of advanced multi-messenger astronomy.

Abstract

GHz radio astronomy has played a fundamental role in the recent dazzling discovery of GW170817, a neutron star (NS)-NS merger observed in both gravitational waves (GWs) and light at all wavelengths. Here we show how the expected progress in sensitivity of ground-based GW detectors over the next decade calls for U.S.-based GHz radio arrays to be improved beyond current levels. We discuss specifically how several new scientific opportunities would emerge in multi-messenger time-domain astrophysics if a next generation GHz radio facility with sensitivity and resolution $10\times$ better than the current Jansky Very Large Array (VLA) were to work in tandem with ground-based GW detectors. These opportunities include probing the properties, structure, and size of relativistic jets and wide-angle ejecta from NS-NS mergers, as well as unraveling the physics of their progenitors via host galaxy studies.