TY - JOUR
T1 - Late-time radio observations of the short GRB 200522A
T2 - Constraints on the magnetar model
AU - Bruni, G.
AU - O'connor, B.
AU - Matsumoto, T.
AU - Troja, E.
AU - Piran, T.
AU - Piro, L.
AU - Ricci, R.
N1 - Publisher Copyright:
© 2021 Oxford University Press. All rights reserved.
PY - 2021/7/1
Y1 - 2021/7/1
N2 - GRB 200522A 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 data set 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 GRB 200522A, carried out with the Karl G. Jansky Very Large Array at 288 d after the burst. For kilonova ejecta with energy Eej≈ 1053erg, as expected for a long-lived magnetar remnant, we can already rule out ejecta masses Mej≲ 0.03M⊙for the most likely range of circumburst densities n ≳ 10-3cm-3. Observations on timescales of ≈3-10 yr after the merger will probe larger ejecta masses up to Mej∼0.1M⊙, providing a robust test to the magnetar scenario.
AB - GRB 200522A 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 data set 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 GRB 200522A, carried out with the Karl G. Jansky Very Large Array at 288 d after the burst. For kilonova ejecta with energy Eej≈ 1053erg, as expected for a long-lived magnetar remnant, we can already rule out ejecta masses Mej≲ 0.03M⊙for the most likely range of circumburst densities n ≳ 10-3cm-3. Observations on timescales of ≈3-10 yr after the merger will probe larger ejecta masses up to Mej∼0.1M⊙, providing a robust test to the magnetar scenario.
KW - Gamma-ray bursts: individual: GRB 200522A
KW - Stars: magnetars
KW - Stars: neutron
UR - http://www.scopus.com/inward/record.url?scp=85107880824&partnerID=8YFLogxK
U2 - 10.1093/mnrasl/slab046
DO - 10.1093/mnrasl/slab046
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AN - SCOPUS:85107880824
SN - 1745-3925
VL - 505
SP - L41-L45
JO - Monthly Notices of the Royal Astronomical Society: Letters
JF - Monthly Notices of the Royal Astronomical Society: Letters
IS - 1
ER -