The afterglow onset for GRB060418 and GRB060607A
Abstract
Gamma-ray burst are thought to be produced by highly relativistic outflows. Although upper and lower limits for the outflow initial Lorentz factor are available, observational efforts to derive a direct determination of have so far failed or provided ambiguous results. As a matter of fact, the shape of the early-time afterglow light curve is strongly sensitive on which determines the time of the afterglow peak, i.e. when the outflow and the shocked circumburst material share a comparable amount of energy. We now comment early-time observations of the near-infrared afterglows of GRB 060418 and GRB 060607A performed by the REM robotic telescope. For both events, the afterglow peak was singled out and allowed us to determine the initial fireball Lorentz, .
Cite
@article{arxiv.0710.0727,
title = {The afterglow onset for GRB060418 and GRB060607A},
author = {S. Covino and S. D. Vergani and D. Malesani and E. Molinari and P. D'Avanzo and G. Chincarini and F. M. Zerbi and L. A. Antonelli and P. Conconi and V. Testa and G. Tosti and F. Vitali and F. D'Alessio and G. Malaspina and L. Nicastro and E. Palazzi and D. Guetta and S. Campana and P. Goldoni and N. Masetti and E. J. A. Meurs and A. Monfardini and L. Norci and E. Pian and S. Piranomonte and D. Rizzuto and M. Stefanon and L. Stella and G. Tagliaferri and P. A. Ward and G. Ihle and L. Gonzalez and A. Pizarro and P. Sinclair and J. Valenzuela},
journal= {arXiv preprint arXiv:0710.0727},
year = {2012}
}
Comments
This contribution is part of the proceedings of the Frascati Workshop 2007, edited by F. Giovannelli and L. Sabau-Graziati, published in a special volume of the Chinese Journal of Astronomy and Astrophysics (ChJAA)