A Radio Counterpart to a Neutron Star Merger

Creators: Hallinan, G.; Corsi, A.; Mooley, K. P.; Hotokezaka, K.; Nakar, E.; Kasliwal, M. M.; Kaplan, D. L.; Frail, D. A.; Myers, S. T.; Murphy, T.; De, K.; Dobie, D.; Allison, J. R.; Bannister, K. W.; Bhalerao, V.; Chandra, P.; Clarke, T. E.; Giacintucci, S.; Ho, A. Y. Q.; Horesh, A.; Kassim, N. E.; Kulkarni, S. R.; Lenc, E.; Lockman, F. J.; Lynch, C.; Nichols, D.; Nissanke, S.; Palliyaguru, N.; Peters, W. M.; Piran, T.; Rana, J.; Sandler, E. M.; Singer, L. P.

Abstract

Gravitational waves have been detected from a binary neutron star merger event, GW170817. The detection of electromagnetic radiation from the same source has shown that the merger occurred in the outskirts of the galaxy NGC 4993, at a distance of 40 megaparsecs from Earth. We report the detection of a counterpart radio source that appears 16 days after the event, allowing us to diagnose the energetics and environment of the merger. The observed radio emission can be explained by either a collimated ultrarelativistic jet, viewed off-axis, or a cocoon of mildly relativistic ejecta. Within 100 days of the merger, the radio light curves will enable observers to distinguish between these models, and the angular velocity and geometry of the debris will be directly measurable by very long baseline interferometry.

Additional Information

© 2017 American Association for the Advancement of Science. Received 17 September 2017; accepted 9 October 2017; published online 16 October 2017. G.H., A.C., and K.P.M. acknowledge the support and dedication of the staff of the National Radio Astronomy Observatory and particularly thank the VLA director, M. McKinnon, as well as A. Mioduszewski and the VLA schedulers, for making the VLA campaign possible. We thank the staff of the GMRT that made these observations possible. The GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. The Australia Telescope Compact Array is part of the Australia Telescope National Facility, which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We thank the Green Bank Observatory for their rapid response to our Director's Discretionary Time GBT proposal. The National Radio Astronomy Observatory and the Green Bank Observatory are facilities of the National Science Foundation operated under a cooperative agreement by Associated Universities Inc. Supported by NSF award AST-1654815 (G.H.); NSF CAREER award 1455090 "Radio and gravitational-wave emission from the largest explosions since the Big Bang" (A.C. and N.P.); the Oxford Centre for Astrophysical Surveys, funded through the Hintze Family Charitable Foundation (K.P.M.); ERC starting grant GRB/SN and ISF grant 1277/13 (E.N.); the Government of India Department of Science and Technology via SwarnaJayanti Fellowship awards DST/SJF/PSA-01/2014-15 (P.C.); the I-Core Program of the Planning and Budgeting Committee and the Israel Science Foundation (A.H.); Australian Research Council grant FT150100099 (T.M.); the GROWTH (Global Relay of Observatories Watching Transients Happen) project, funded by NSF under PIRE grant 1545949; NSF grant AST-1412421 (D.L.K.); Advanced ERC grant TReX (T.P.); the Science and Engineering Research Board, Department of Science and Technology, India, for the GROWTH-India project (V.B.); and NSF Graduate Research Fellowship DGE-1144469 (A.Y.Q.H.). GROWTH is a collaborative project of the California Institute of Technology, University of Maryland–College Park, University of Wisconsin–Milwaukee, Texas Tech University, San Diego State University, Los Alamos National Laboratory, Tokyo Institute of Technology, National Central University (Taiwan), Indian Institute of Astrophysics (India), Inter-University Center for Astronomy and Astrophysics (India), Weizmann Institute of Science (Israel), Oskar Klein Centre at Stockholm University (Sweden), Humboldt University (Germany), and Liverpool John Moores University (UK). This work is part of the research program Innovational Research Incentives Scheme (Vernieuwingsimpuls), financed by the Netherlands Organization for Scientific Research through NWO VIDI grant 639.042.612-Nissanke and NWO TOP grant 62002444-Nissanke. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics in 3D (ASTRO 3D), project CE170100013, and by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), project CE110001020. Basic research in radio astronomy at the Naval Research Laboratory (NRL) is funded by 6.1 Base funding. Construction and installation of VLITE was supported by NRL Sustainment Restoration and Maintenance funding. The VLA data reported in this paper are available from G.H. upon request.

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