General Considerations

Type II and Type Ib supernovae are thought to be produced by a gravitational core-collapse of massive progenitor stars with a mass $M_{\star} \gtrsim 8~M_{\odot}$.

Baade and Zwicky were first to connect supernova explosions with neutron star formation in 1934 [#!baade!#], and the theory that describes neutrino bursts implicated by supernovae and neutron stars has been developed especially during the last four decades. The phenomenon of the supernova touches several fields of physics, from nuclear to plasma physics and hydrodynamics, from astrophysics and stellar theory to neutrino physics. The explosion mechanism of a supernova develops in different stages, from the progenitor star formation to the collapse phase triggering the supernova onset and liberating the emergent neutrino burst, which precedes the emission of the light.

The gravitational energy liberated by core collapse is estimated to be

$$\Delta E_{G} = -{\left({\frac {GM_{core}^{2}}{R_{Fe~core}}} ... ...re}^{2}}{R_{Neutro~Star}}} \right)} \sim O(10^{53}) {\rm erg}.$$ (3)

which represents the difference in the binding energy between the core and the growing neutron star [#!suzuki!#,#!burrows!#]. The second term is dominant, due to the tiny neutron star radius (10 km only). This incredible amount of energy is distributed in different forms as follows. The optical emission which corresponds to the total light radiated, amounts to only $\sim 0.01$ % of the gravitational energy, i.e. $E_{rad}$ is of $O(10^{49})$ erg. The kinetic energy of the debris is just 1 % of the gravitational energy, i.e. $E_{rad}$ is of $O(10^{51})$ erg. Full 99 % of the released energy is emitted in form of neutrinos, $E_{\nu}$ is of $O(10^{53})$ erg [#!burrows!#]. In contrast to the thermonuclear explosion, here neutrinos play the fundamental role. Because of the profound opacity of the dense core to light, the neutrinos are the only messengers, which give us the possibility to `see' directly the supernova core.