Change search
ReferencesLink to record
Permanent link

Direct link
Stockholm University, Faculty of Science, Department of Astronomy.
2008 (English)In: The Astrophysical Journal, Vol. 672Article in journal (Refereed) Published
Abstract [en]

The optical-UV component in GRB 060218 is assumed to be due to optically thick cyclotron emission. The key aspect of this model is the high temperature of the absorbing electrons. The heat input derives from nuclei accelerated in semirelativistic internal shocks, like in ordinary gamma-ray bursts. Coulomb collisions transfer part of that energy to electrons. Inverse Compton cooling on the X-ray photons leads to electron temperatures around ~100 keV. Such a high brightness temperature for the optical-UV emission implies an emitting area roughly equal to that of the thermal X-ray component. This suggests a model in which the radio, optical-UV, and thermal X-ray emission are closely related. Although the optical-UV and thermal X-ray emission are two separate spectral components, it is argued that they both come from the photosphere of a quasi-spherical, continuous outflow, whose interaction with the circumstellar medium gives rise to the radio emission. The properties of GRB 060218, as measured in the comoving frame, are similar to those of ordinary gamma-ray bursts; i.e., the main difference is the much lower value of the bulk Lorentz factor in GRB 060218. The cyclotron absorption implies a magnetic field in rough equipartition with the matter energy density in the outflow. Hence, the magnetic field could have a dynamically important role, possibly with a magnetar as the central engine.

Place, publisher, year, edition, pages
2008. Vol. 672
Keyword [en]
gamma rays: bursts, magnetic fields, radiation mechanisms: nonthermal, radiation mechanisms: thermal
URN: urn:nbn:se:su:diva-17264OAI: diva2:183785
Available from: 2009-01-12 Created: 2009-01-12 Last updated: 2009-11-13Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Björnsson, Claes-Ingvar
By organisation
Department of Astronomy

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 31 hits
ReferencesLink to record
Permanent link

Direct link