DOI

https://doi.org/10.48717/9qp4-ga70

Project

RM016

Title

RM016A

Abstract

On Thursday 15 October 2020, a new gamma-ray burst (GRB) was discovered by Swift/BAT: GRB 201015A. Right after the detection, the field was monitored with different multiwavelength observations that already produced interesting conclusions: GRB 201015A appears to be a luminous short GRB (although some results point at the same time to a long GRB origin), more than thousand times more luminous than the first neutron star merger GW 170817, and likely the first short GRB ever detected up to TeV energies. Remarkably, GRB 201015A has already been detected at radio frequencies (1.4 days post-burst) with a flux density larger than the peak emission reported in GW 170817, that occured ∼ 100 days post-burt. And this becomes even more remarkable considering that its luminosity distance is 2.3 Gpc, almost 60 times farther than the 40 Mpc of GW 170817. The only approach to unveil the nature of the radio afterglow is to conduct VLBI observations that would allow us to determine its proper motion (and source compactness). We request up to four EVN+eMERLIN observations on GRB 201015A at 5 GHz (one out-of-session, as soon as possible; three during regular e-EVN sessions) to constrain the physical properties of this event. A direct comparison with GW 170817 would provide valuable information about the parameter space of short GRBs and how the environment properties affect to the evolution of the radio afterglow.