Speaker: German Lugones
Instituto de Astronomia, Geofisica e Ciencias Atmosfericas (Sao Paulo, Brazil)

``Quark matter, supernovae and gamma ray bursts''


Although more than three decades of theoretical research and hard 
numerical modeling have been invested, the mechanism that causes 
the explosion of  massive stars is still not completely understood. 
This suggests missing  physics, possibly related with a transition 
to quark phases during the deleptonization phase of proto-neutron stars. 
In the first part of the seminar a brief review of the present status 
of the standard model of core  collapse supernovae and protoneutron 
star formation is presented. Then we  discuss some properties of matter 
at very high densities, the transition  to deconfined quark phases 
in supernovae and protoneutron stars, the effects of the transition in the
 explosion mechanism, and the possible production of gamma ray bursts.
An interesting feature of the transition is that the influence of the
magnetic field expected to be present in neutron star interiors has a
dramatic effect on the propagation of the combustion front, generating a
strong acceleration of the flame in the polar direction. This results in
a (transitory) strong asymmetry in the geometry of the just formed core
of hot quark matter. This geometrical asymmetry gives rise to a bipolar 
emission of the thermal neutrino-antineutrino pairs produced in the process
of quark matter formation. Further annihilation into electron-positron
pairs just above the polar caps, gives rise to a relativistic fireball, 
thus providing a suitable explanation for the inner engine of short gamma
ray bursts.