Deep ATCA and VLA Radio Observations of Short-GRB Host Galaxies. Constraints on Star Formation Rates, Afterglow Flux, and Kilonova Radio Flares

Klose, S.S.KloseNicuesa Guelbenzu, A. M.A. M.Nicuesa GuelbenzuMichałowski, M. J.M. J.MichałowskiHUNT, Leslie KippLeslie KippHUNTHartmann, D. H.D. H.HartmannGreiner, J.J.GreinerROSSI, AndreaAndreaROSSIPalazzi, E.E.PalazziBernuzzi, S.S.Bernuzzi2021-01-082021-01-0820190004-637Xhttp://hdl.handle.net/20.500.12386/29625We report the results of an extensive radio-continuum observing campaign of host galaxies of short gamma-ray bursts (GRBs). The goal of this survey was to search for optically obscured star formation, possibly indicative of a population of young short-GRB progenitors. Our sample comprises the hosts and host-galaxy candidates of 16 short-GRBs from 2005 to 2015, corresponding to roughly one-third of the presently known ensemble of well-localized short bursts. Eight GRB fields were observed with ATCA (at 5.5 and 9.0 GHz), and eight fields with the VLA (mostly at 5.5 GHz). The observations typically achieved a 1σ rms of 5-8 μJy. In most cases, they were performed years after the corresponding burst. No new short-GRB host with optically obscured star formation was found. Only one host galaxy was detected: that of GRB 100206A at z = 0.407. However, its starburst nature was already known from optical/IR data. Its measured radio flux can be interpreted as being due to a star formation rate of about 60 M ☉ yr-1. This is in good agreement with earlier expectations based on the observed broad-band spectral energy distribution of this galaxy. The 15 nondetections constrain the SFRs of the suspected host galaxies and provide upper limits on late-time luminosities of the associated radio afterglows and predicted kilonova radio flares. The nondetection of radio emission from GRB explosion sites confirms the intrinsically low luminosity of short-GRB afterglows and places significant constraints on the parameter space of magnetar-powered radio flares. Luminous radio flares from fiducial massive magnetars have not been found.STAMPAenDeep ATCA and VLA Radio Observations of Short-GRB Host Galaxies. Constraints on Star Formation Rates, Afterglow Flux, and Kilonova Radio FlaresArticle10.3847/1538-4357/ab528a2-s2.0-85077302422000506012000100https://iopscience.iop.org/article/10.3847/1538-4357/ab528a2019ApJ...887..206KFIS/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