ELECTRON AND POSITRON PAIR PRODUCTION IN GRAVITATIONAL COLLAPSES

Abstract

Neutral stellar cores at or over nuclear densities are described by positive charged baryon cores and negative charged electron gas since they possess different masses and interactions (equations of state). Based on a simplified model of spherically collapsing cores, we approximately integrate the Einstein-Maxwell equations and the equations for the particle number and energy-momentum conservation. It is shown that in gravitational collapse, electron-positron pairs are produced and gravitational energy is converted to electron-positron energy, which might account for the energy source of gamma-ray bursts. Introduction. In the gravitational collapse of neutral stellar cores at densities compara- ble to the nuclear density, complex dynamical processes are expected to take place. These involve both macroscopic processes such as gravitational and hydrodynamical processes, as well as microscopic processes due to the strong and electroweak interactions. The time and length scales of macroscopic processes are much larger than those of the microscopic processes. Despite the existence of only a few exact solutions of Einstein's equations for simplified cases, macroscopic processes can be studied rather well by numerical algorithms. In both analytical solutions and numerical simulations, microscopic processes are approxi- mately treated as local and instantaneous processes which are effectively represented by a model-dependent parameterized equation of state (EOS). We call this approximate locality. In these approaches, it is rather difficult to simultaneously analyze both macroscopic and microscopic processes charactgerized by such different time and length scales. Applying approximate locality to electric processes, as required by the charge conservation, one is led to local neutrality: positive and negative charge densities are exactly equal over