GRB 000926 and its optical afterglow: Another evidence for non-isotropic emission
Abstract
CCD Johnsons BV and Cousins RI photometric magnitudes are determined for 20 stars in the field of GRB 000926. Using them as calibrators, B and R band light curves are constructed of the afterglow from ours and other published observations. They show a steepening of the flux decay, from a decay constant of 1.4+/-0.1 to 2.6+/-0.06 at about 1.7 days after the burst. Attributing this break to the onset of sideways expansion of a jet-like ejecta, we estimate an initial jet opening angle of ~0.14 radian, and a burst energy of ~10^51 erg. We construct the X-ray-optical-near infrared spectrum of the afterglow and derive a spectral index of ~ -0.9. From the spectrum we also estimate that the source has a rather large intrinsic extinction, amounting to E(B-V)=0.36+/-0.02.
Cite
@article{arxiv.astro-ph/0010212,
title = {GRB 000926 and its optical afterglow: Another evidence for non-isotropic emission},
author = {R. Sagar and S. B. Pandey and V. Mohan and D. Bhattacharya and A. J. Castro-Tirado},
journal= {arXiv preprint arXiv:astro-ph/0010212},
year = {2007}
}
Comments
13 pages, 3 figures, accepted for publication in Bull. Astr. Soc. India