A candidate coherent radio flash following a neutron star merger
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 being co-located with the GRB 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 $6.7^{+6.6}_{-4.4} \times 10^{32}$ 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).
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Author affiliation
College of Science & Engineering Physics & AstronomyVersion
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