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Published May 10, 2018 | Published + Submitted
Journal Article Open

A Turnover in the Radio Light Curve of GW170817


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 × 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.

Additional Information

© 2018 The American Astronomical Society. Received 2018 March 18; revised 2018 April 26; accepted 2018 April 27; published 2018 May 9. We thank P. Chang for helpful discussions. T.M. acknowledges the support of the Australian Research Council through grant FT150100099. A.C. acknowledges support from the NSF CAREER award #1455090. Part of this research was conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020. Part of this work was supported by the Global Relay of Observatories Watching Transients Happen (GROWTH) project funded by the National Science Foundation under PIRE grant No. 1545949. D.K. was additionally supported by by NSF grant AST-1412421. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. K.P.M. is currently a Jansky Fellow of the National Radio Astronomy Observatory. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. Facilities: ATCA - Australia Telescope Compact Array, VLA - Very Large Array. Software: Astropy (The Astropy Collaboration et al. 2018), MIRIAD (Sault et al. 1995), DIFMAP (Shepherd 1997), CASA (McMullin et al. 2007).

Attached Files

Published - Dobie_2018_ApJL_858_L15.pdf

Submitted - 1803.06853.pdf


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August 19, 2023
October 18, 2023