A Turnover in the Radio Light Curve of GW170817

Dougal Dobie, David L. Kaplan, Tara Murphy, Emil Lenc, Kunal P. Mooley, Christene Lynch, Alessandra Corsi, Dale Frail, Mansi Kasliwal, Gregg Hallinan

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79 Scopus citations


We present 2-9 GHz radio observations of GW170817 covering the period 125-200 days post-merger, taken with the Australia Telescope Compact Array (ATCA) and the Karl G. Jansky Very Large Array (VLA). Our observations demonstrate that the radio afterglow peaked at 149 ±2 days post-merger and is now declining in flux density. We see no evidence for evolution in the radio-only spectral index, which remains consistent with optically thin synchrotron emission connecting the radio, optical, and X-ray regimes. The peak implies a total energy in the synchrotron-emitting component of a few × 1050 erg. The temporal decay rate is most consistent with mildly or non-relativistic material and we do not see evidence for a very energetic off-axis jet, but we cannot distinguish between a lower-energy jet and more isotropic emission.

Original languageEnglish
Article numberL15
JournalAstrophysical Journal Letters
Issue number2
StatePublished - May 10 2018


  • gravitational waves
  • radio continuum: stars
  • stars: neutron


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