GRB990712: First Indication of Polarization Variability in a Gamma-ray Burst Afterglow
Abstract
We report the detection of significant polarization in the optical afterglow of GRB990712 on three instances 0.44, 0.70 and 1.45 days after the gamma-ray burst, with (P, theta) being (2.9% +- 0.4%, 121.1 degr +- 3.5 degr), (1.2% +- 0.4%, 116.2 degr +- 10.1 degr) and (2.2% +- 0.7%, 139.2 degr +- 10.4 degr) respectively. The polarization is intrinsic to the afterglow. The degree of polarization is not constant, and smallest at the second measurement. The polarization angle does not vary significantly during these observations. We find that none of the existing models predict such polarization variations at constant polarization angle, and suggest ways in which these models might be modified to accommodate the observed behavior of this afterglow.
Cite
@article{arxiv.astro-ph/0007015,
title = {GRB990712: First Indication of Polarization Variability in a Gamma-ray Burst Afterglow},
author = {E. Rol and R. A. M. J. Wijers and P. M. Vreeswijk and L. Kaper and T. J. Galama and J. van Paradijs and C. Kouveliotou and N. Masetti and E. Pian and E. Palazzi and F. Frontera and E. P. J. van den Heuvel},
journal= {arXiv preprint arXiv:astro-ph/0007015},
year = {2009}
}
Comments
10 pages including 6 figures, accepted by ApJ. Uses aastex 5.0