GRB 070311: a common origin for the prompt and afterglow emission

GRB 070311 was a long burst that triggered INTEGRAL. We present prompt γ‐ray, early NIR/optical, late optical and X‐ray data on this burst and its afterglow. Interestingly, the H‐band light curve acquired with REM exhibits two pulses at 80 and 140 s after the peak of the γ‐ray burst, with possible evidence for a contemporaneous faint γ‐ray tail. The late optical and X‐ray afterglow underwent a rebrightening between 3×104 and 2×105 s after the burst with energy comparable with that of the prompt emission extrapolated in the X‐ray band. After fitting the early γ‐ray and optical light curves, we modelled the time profile of the late rebrightening as the time‐rescaled version of the prompt γ‐ray pulse over an underlying power law. This result supports a common origin for both prompt and late X‐ray/optical afterglow rebrightening of GRB 070311 within the external shock scenario.