Bruni, GabrieleGabrieleBruniO'Connor, B.B.O'ConnorMatsumoto, T.T.MatsumotoTroja, E.E.TrojaPiran, T.T.PiranPIRO, LUIGILUIGIPIRORICCI, ROBERTOROBERTORICCI2022-03-282022-03-2820211745-3925http://hdl.handle.net/20.500.12386/31982GRB200522A 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.STAMPAenArticle10.1093/mnrasl/slab0462-s2.0-85107880824http://arxiv.org/abs/2105.01440v1https://academic.oup.com/mnrasl/article/505/1/L41/6271321?login=trueFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation