In this paper, we present rapid follow-up observations of the short GRB 201006A, consistent with being a compact binary merger, using the LOw Frequency ARray (LOFAR). We have detected a candidate 5.6σ, short, coherent radio flash at 144 MHz at 76.6 mins post-GRB with a 3σ duration of 38 seconds. This radio flash is 27 arcsec offset from the GRB location, which has a probability of occurring by chance of ∼0.05% (3.8σ) when accounting for measurement uncertainties. Despite the offset, we show that the probability of finding an unrelated transient within 40 arcsec of the GRB location is <10−6 and conclude that this is a candidate radio counterpart to GRB 201006A. We performed image plane dedispersion and the radio flash is tentatively (2.4σ) shown to be highly dispersed, allowing a distance estimate, corresponding to a redshift of 0.58±0.06. The corresponding luminosity of the event at this distance is 6.7−4.4+6.6×1032 erg s−1 Hz−1. If associated with GRB 201006A, this emission would indicate prolonged activity from the central engine that is consistent with being a newborn, supramassive, likely highly magnetised, millisecond spin neutron star (a magnetar).
@article{arxiv.2312.04237,
title = {A candidate coherent radio flash following a neutron star merger},
author = {A. Rowlinson and I. de Ruiter and R. L. C. Starling and K. M. Rajwade and A. Hennessy and R. A. M. J. Wijers and G. E. Anderson and M. Mevius and D. Ruhe and K. Gourdji and A. J. van der Horst and S. ter Veen and K. Wiersema},
journal= {arXiv preprint arXiv:2312.04237},
year = {2024}
}