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An Intermediate-Mass Binary Star Origin of Long Gamma-ray Bursts

Speaker Dr. Herbert Lau
Affiliation Centre for Stellar and Planetary Astrophysics, Monash University, Australia
Date December 21, 2009 (Mon)
Time 11:00a.m. - 12:00 n.n.
Venue Room 522, 5/F, Chong Yuet Ming Physics Building, HKU

Abstract:

The stellar origin of gamma-ray bursts can be explained by the rapid release of energy in a highly collimated, extremely relativistic jet. This in turn appears to require a rapidly spinning highly magnetised stellar core that collapses into a magnetic neutron star or a black hole within a relatively massive envelope. To satisfy all these requirements we hypothesize a binary star model that ends with the merging of an oxygen neon white dwarf with the carbon/oxygen core of a naked helium star at the end of a common envelope phase of evolution. The rapid spin and high magnetic field are a natural consequence of such a merging. The evolution that leads to these progenitors is convoluted and so naturally occurs only very rarely. To test the hypothesis we evolve a population of progenitors and find that the rate is as required.

 

Coffee and tea will be served 20 minutes prior to the seminar.