A Turnover in the Radio Light Curve of GW170817

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

来源：Astrophysical Journal Letters, 2018, 858(2): L15.

DOI：10.3847/2041-8213/aac105

<jats:title>Abstract</jats:title>
<jats:p>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<jats:sup>50</jats:sup> 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.</jats:p>

• 出版日期2018-5-10