Late-time radio observations of the short GRB200522A: constraints on the magnetar model
Date Issued
2021
Author(s)
Abstract
GRB200522A is a short duration gamma-ray burst (GRB) at redshift $z$=0.554
characterized by a bright infrared counterpart. A possible, although not
unambiguous, interpretation of the observed emission is the onset of a luminous
kilonova powered by a rapidly rotating and highly-magnetized neutron star,
known as magnetar. A bright radio flare, arising from the interaction of the
kilonova ejecta with the surrounding medium, is a prediction of this model.
Whereas the available dataset remains open to multiple interpretations (e.g.
afterglow, r-process kilonova, magnetar-powered kilonova), long-term radio
monitoring of this burst may be key to discriminate between models. We present
our late-time upper limit on the radio emission of GRB200522A, carried out with
the Karl G. Jansky Very Large Array at 288 days after the burst. For kilonova
ejecta with energy $E_{\rm ej} \approx 10^{53} \rm erg$, as expected for a
long-lived magnetar remnant, we can already rule out ejecta masses $M_{\rm ej}
\lesssim0.03 \mathrm{M}_\odot$ for the most likely range of circumburst
densities $n\gtrsim 10^{-3}$ cm$^{-3}$. Observations on timescales of
$\approx$3-10 yr after the merger will probe larger ejecta masses up to $M_{\rm
ej} \sim 0.1 \mathrm{M}_\odot$, providing a robust test to the magnetar
scenario.
Volume
505
Issue
1
Start page
L41
Issn Identifier
1745-3925
Rights
open.access
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