Multi-Color Observations of the GRB000926 Afterglow
Abstract
We present multi-color light-curves of the optical afterglow of GRB 000926. Beginning ~1.5 days after the burst, the light-curves of this GRB steepen measurably. The existence of such achromatic breaks are usually taken to be an important observational signature that the ejecta are not expanding isotropically, but rather have a collimated jet-like geometry. If we interpret the data in this context, we derive an opening angle of 5 degrees, which reduces the energy release compared to an isotropic model by a factor of ~275, to 1.7 x 10^51 erg. To fit the data with a simple jet model requires extinction along the line of sight. The derived A_V is in the range 0.11 - 0.82 mag, depending on the adopted extinction law and whether the electrons giving rise to the optical emission are undergoing synchrotron cooling or not. Since this is in excess of the expected extinction from our Galaxy, we attribute this to the GRB host. We note that this extinction is typical of a galactic disk, and therefore the event likely took place in the disk of its host.
Keywords
Cite
@article{arxiv.astro-ph/0012303,
title = {Multi-Color Observations of the GRB000926 Afterglow},
author = {P. A. Price and F. A. Harrison and T. J. Galama and D. E. Reichart and T. S. Axelrod and E. J. Berger and J. S. Bloom and J. Busche and T. Cline and A. Diercks and S. G. Djorgovski and D. A. Frail and A. Gal-Yam and J. Halpern and J. A. Holtzman and M. Hunt and K. Hurley and B. Jacoby and R. Kimble and S. R. Kulkarni and N. Mirabal and G. Morrison and E. Ofek and O. Pevunova and R. Sari and B. P. Schmidt and D. Turnshek and S. Yost},
journal= {arXiv preprint arXiv:astro-ph/0012303},
year = {2009}
}
Comments
4 pages, 2 figures, 2 tables. Accepted for publication in ApJ Letters