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Published November 10, 2016 | Published + Submitted
Journal Article Open

Radio Counterparts of Compact Binary Mergers Detectable in Gravitational Waves: A Simulation for an Optimized Survey


Mergers of binary neutron stars and black hole–neutron star binaries produce gravitational-wave (GW) emission and outflows with significant kinetic energies. These outflows result in radio emissions through synchrotron radiation. We explore the detectability of these synchrotron-generated radio signals by follow-up observations of GW merger events lacking a detection of electromagnetic counterparts in other wavelengths. We model radio light curves arising from (i) sub-relativistic merger ejecta and (ii) ultra-relativistic jets. The former produce radio remnants on timescales of a few years and the latter produce γ-ray bursts in the direction of the jet and orphan-radio afterglows extending over wider angles on timescales of weeks. Based on the derived light curves, we suggest an optimized survey at 1.4 GHz with five epochs separated by a logarithmic time interval. We estimate the detectability of the radio counterparts of simulated GW-merger events to be detected by advanced LIGO and Virgo by current and future radio facilities. The detectable distances for these GW merger events could be as high as 1 Gpc. Around 20%–60% of the long-lasting radio remnants will be detectable in the case of the moderate kinetic energy of 3 · 10^(50) erg and a circum-merger density of 0.1 cm^(-3) or larger, while 5%–20% of the orphan-radio afterglows with kinetic energy of 1048 erg will be detectable. The detection likelihood increases if one focuses on the well-localizable GW events. We discuss the background noise due to radio fluxes of host galaxies and false positives arising from extragalactic radio transients and variable active galactic nuclei, and we show that the quiet radio transient sky is of great advantage when searching for the radio counterparts.

Additional Information

© 2016 The American Astronomical Society. Received 2016 May 30; revised 2016 August 25; accepted 2016 September 3; published 2016 November 8. This work was supported by the I-CORE Program of the Planning and Budgeting Committee and The Israel Science Foundation (grant No 1829/12) and by an ISF-CNSF grant. SMN acknowledges generous support from the Radboud University Excellence Fellowship. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We are very grateful to Dale Frail for a careful reading of the manuscript and for initially encouraging us to embark on this project. We thank Keith Bannister, Paz Beniamin, Robert Braun, Jess Broderick, Aaron Chippendale, Assaf Horesh, Rob Fender, Jason Hessels, David Kaplan, Mansi Kasliwal, Shri Kulkarni, Duncan Lorimer, Kunal Mooley, Tara Murphy, Steve Myers, and Antonia Rowlinson for useful discussions. We thank the anonymous referee for suggestions that improved our work.

Attached Files

Published - Hotokezaka_2016_ApJ_831_190.pdf

Submitted - 1605.09395v2.pdf


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