Modelling GRB021004 by multiple energy injections

GRB021004 is one of the best sampled gamma-ray bursts (GRB) todate, however the nature of its light curve is still being debated. A compilation of multiwavelength (from radio to X-rays) observations, including unpublished optical/near-infrared and millimetre observations, is used to fit a model based on 7 refreshed shocks that took place during the evolution of the afterglow. They imply a total energy release of ∼ 8 × 1051 erg. Analysis of the late photometry reveals that the GRB021004 host is a low extinction (AV ∼ 0.1) starburst galaxy with MB � −22.0

GRB 021004 modelled by multiple energy injections

GRB 021004 is one of the best sampled gamma-ray bursts (GRB) to date, although the nature of its light curve is still being debated. Here we present a large amount (107) of new optical, near-infrared (NIR) and millimetre observations, ranging from 2 hours to more than a year after the burst. Fitting the multiband data to a model based on multiple energy injections suggests that at least 7 refreshed shocks took place during the evolution of the afterglow, implying a total energy release (collimated within an angle of 1.8 deg) of ~ 8x10^51 erg. Analysis of the late photometry reveals that the GRB 021004 host is a low extinction (Av ~ 0.1) starburst galaxy with M_B ~ -22.0.Comment: 9 pages, 5 figures, accepted for publication in A&A