Millimetre Observations of Gamma-ray Bursts at IRAM

¹ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
² Institute de Radioastronomie Milimetrique (IRAM), Saint Martin d'Hères, France
³ Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, India
⁴ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
⁵ Unidad Asociada CSIC-UPV/EHU, Departamento de Física Aplicada I, Escuela T. Superior de Ingeniería, Bilbao, Spain
⁶ Ikerbasque, Basque Foundation for Science, Alameda de Urquijo 36-5, 48008 Bilbao, Spain
⁷ Nikolaev Astronomical Observatory, University of Nikolaev, Ukraine
⁸ Universidad de Jaén, Spain
⁹ ESAC, Robledo de Chavela, Madrid, Spain

Abstract

Since 1997, and following our detection of the first mm afterglow, we have followed-up 70 GRBs, mainly with the IRAMś Plateau de Bure Interferometer, what can be considered as the IRAM Legacy GRB Sample. 66 events were observed at 3 mm, with 19 of them being detected (with another 3 having marginal detections). 32 GRBs were followed up at 1 mm, with 6 of them being detected. Redshifts for the GRB afterglows lie in the range z = 0.03–8.3, with measured flux densities (at 3 mm) varying between 0.25 and 60 mJy (but usually <1.5 mJy) with first observations taking place around 1–2 days after the GRB. Forward shock emission expleains the observations with the exception of one particular case (GRB 090423 at z = 8.2) for which reverse shock emission is required.