2021/05/04 by G. Bruni, B. O'Connor, Brendan O’Connor +7 · 1 citation
Physics and Astronomy · #Afterglow #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Ejecta #Galaxy #Gamma-ray burst #Gamma-ray bursts and supernovae #Kilonova #Magnetar #Neutron star #Physics #Pulsars and Gravitational Waves Research #Redshift #Supernova #astro-ph.HE
paper · pdf · doi:10.1093/mnrasl/slab046
Accepted for publication on MNRAS letters
arxiv created 2021/05/04 · openalex publication_date 2021/05/05 · arxiv updated 2021/05/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT 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 ≈ 1053 \rm erg, as expected for a long-lived magnetar remnant, we can already rule out ejecta masses M\rm ej\lesssim 0.03 M_\odot for the most likely range of circumburst densities n ≳ 10−3 cm−3. Observations on timescales of ≈ 3–10 yr after the merger will probe larger ejecta masses up to Mej ∼ 0.1 M⊙, providing a robust test to the magnetar scenario.