Astron. Astrophys. Suppl. Ser. 138, 405-406

Testing for synchrotron self-absorption in GRB 970111

A. Crider and E.P. Liang

Send offprint request: A. Crider
(acrider@spacsun.rice.edu)
(liang@spacun.rice.edu)

Department of Space Physics and Astronomy, 6100 S. Main, Rice University, Houston, TX 77005-1892, U.S.A.

Received December 18, 1998; accepted January 28, 1999

Abstract:

The time-resolved spectra of several gamma-ray bursts have shown that near the beginning of the burst, some absorption mechanism makes the spectra inconsistent with the simple optically-thin synchrotron shock model. We fit GRB 970111, which shows strong evidence for such absorption, with a synchrotron shock spectra suffering self-absorption. The synchrotron self-absorption shape does fit the BATSE time-evolving spectra, although it may be inconsistent with BeppoSAX WFC data. If the turnover just below the spectral break is due to synchrotron self-absorption, a magnetic field strength of $4 \ 10^7~{\rm G}$ is required.

Key words: gamma-rays: bursts -- gamma-rays: observations -- radiation mechanisms: non-thermal -- techniques: spectroscopic