The optical rebrightening of GRB100814A: an interplay of forward and reverse shocks?

Massimiliano De Pasquale, N. P. M. Kuin, S. Oates, S. Schulze, Z. Cano, C. Guidorzi, A. Beardmore, P. A. Evans, Z. L. Uhm, B. Zhang, M. Page, S. Kobayashi, A. Castro-Tirado, J. Gorosabel, T. Sakamoto, T. Fatkhullin, S. B. Pandey, M. Im, P. Chandra, D. Frail, H. Gao, D. Kopač, Y. Jeon, C. Akerlof, K. Y. Huang, S. Pak, W. -K. Park, A. Gomboc, A. Melandri, S. Zane, C. G. Mundell, C. J. Saxton, S. T. Holland, F. Virgili, Y. Urata, I. Steele. D. Bersier, N. Tanvir, V. V. Sokolov, A. S. Moskvitin

Published 2013-12-05, updated 2015-01-27Version 2

We present a wide dataset of gamma-ray, X-ray, UVOIR, and radio observations of the Swift GRB100814A. At the end of the slow decline phase of the X-ray and optical afterglow, this burst shows a sudden and prominent rebrightening in the optical band only, followed by a fast decay in both bands. The optical rebrightening also shows chromatic evolution. Such a puzzling behaviour cannot be explained by a single component model. We discuss other possible interpretations, and we find that a model that incorporates a long-lived reverse shock and forward shock fits the temporal and spectral properties of GRB100814A the best.