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arXiv · 1803.06853

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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Abstract

We present 2-9 GHz radio observations of GW170817 covering the period 125-200 days post-merger, taken with the Australia Telescope Compact Array and the Karl G. Jansky Very Large Array. Our observations demonstrate that the radio afterglow peaked at $149\pm2$ 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 ${\rm few}\times 10^{50}\,$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.

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Dougal Dobie, David L. Kaplan, Tara Murphy, Emil Lenc, Kunal P. Mooley, Christene Lynch, Alessandra Corsi, Dale Frail, Mansi Kasliwal, Gregg Hallinan. 2018-03-19. A turnover in the radio light curve of GW170817. https://doi.org/10.3847/2041-8213%2Faac105

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