Probing the Darkest Bursts with Radio Observations

Author: Alexander J. van der Horst

Abstract: Since their discovery 15 years ago, the GRB sub-class of dark bursts has received quite a lot of attention. This is caused by the fact that the lack or faintness of the optical emission is most likely due to either a high redshift or an unusually large amount of extinction in the host galaxy. If the optical darkness of a GRB is caused by the latter, the amount of extinction can be determined by means of broadband modeling of its radio and X-ray emission. However, the number of GRBs for which this is possible is very low. In this talk I will present and discuss radio observations with WSRT and the AMI Large Array of GRB 111215A, and the broadband modeling of the complete data set available for this GRB, which is among the darkest bursts ever found. I will also put this in context of population of dark bursts as a whole, and in particular those detected at radio wavelengths.