Pair emission from bare magnetized strange stars

The dominant emission from bare strange stars is thought to be electron-positron pairs, produced through spontaneous pair creation (SPC) in a surface layer of electrons tied to the star by a superstrong electric field. The positrons escape fr eely, but the electrons are directed towards the star and quickly fill all available states, such t hat their degeneracy suppresses further SPC. An electron must be reflected and gain energy in orde r to escape, along with the positron. Each escaping electron leaves a hole that is immediately filled by another electron through SPC. We discuss the collisional processes that produce escaping electrons. When the Landau quantization of the motion perpendicular to the magnetic field is taken into account, electron-electron collisions can lead to an escaping elect ron only through a multi-stage process involving higher Landau levels. Although the available estimates of the collision rate are deficient in several ways, it appears that the rate is too low f or electron-electron collisions to be effective. A simple kinetic model for electron-quark collisions leads to an estimate of the rate of pair production that is analogous to thermionic e mission, but the work function is poorly determined.