Volume 369, Number 2, April II 2001
|Page(s)||694 - 705|
|Published online||15 April 2001|
Large scale magnetic fields and their dissipation in GRB fireballs
Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching bei München, Germany
Corresponding author: H. C. Spruit, firstname.lastname@example.org
Accepted: 17 January 2001
We consider possible geometries of magnetic fields in GRB outflows, and their evolution with distance from the source. For magnetically driven outflows, with an assumed ratio of magnetic to kinetic energy density of order unity, the field strengths are sufficient for efficient production of γ-rays by synchrotron emission in the standard internal shock scenario, without the need for local generation of small scale fields. In these conditions, the MHD approximation is valid to large distances (1019 cm). In outflows driven by nonaxisymmetric magnetic fields, changes of direction of the field cause dissipation of magnetic energy by reconnection. Much of this dissipation takes place outside the photosphere of the outflow, and can convert a significant fraction of the magnetic energy flux into radiation.
Key words: gamma-ray bursts / magnetic fields / radiation mechanisms: nonthermal / shock waves
© ESO, 2001
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.