Powering GRBs: Blandford-Znajek mechanism Vs. neutrino heating
by
Ivan Zalamea(Dept of Astronomy, Stockholm University)
→
Europe/Stockholm
FA31
FA31
Description
Observations of gamma ray bursts (GRBs) imply the emission of 10^(48--52) erg in about 0.1--100 seconds. The short temporal variability on the light curve of these bursts (~ ms) and the typical energy of the observed photons (~ MeV) require a compact region and also radiating matter moving with ultra-relativistic speeds. Leading theories to explain the formation of an ultra-relativistic outflow invoke the presence of a central black hole and at least one of the following two ingredients: a hyper-accreting disc or a large-scale and strong magnetic field. In the talk, an overview of GBR observations will be followed by a description of the main characteristics of competing theories for GRB central engines. We will set an upper limit to the power available via the Blandford-Znajek mechanism assuming that the large scale magnetic field is sustained by an accretion disc. From such a disc we expect the release of large fluxes of neutrinos and antineutrinos. We will then compare the power available from neutrino annihilation to the power available from the Blandford-Znajek mechanism.
