The bump in the afterglow of GRB 050525A: SN or light echo?

摘要

We present VLT observations of GRB 050525A at, z = 0.606. We find that the early-time light curve is well described by a broken power law with a break at t ~ 0.3 d after the burst. About ~ 5d after the burst, a flattening is apparent, followed by a further dimming. Both the magnitude and the shape of the light curve suggest that a supernova 1998bw-like was emerging during the late decay of the afterglow. Alternative explanations, like a light echo component, are not completely ruled out by our data.