Thermalization of electron-positron plasma with quantum degeneracy

TL;DR

This study investigates how electron-positron-photon plasmas reach thermal equilibrium, emphasizing the role of quantum degeneracy and relativistic effects, using detailed QED-based collision calculations.

Contribution

It provides a comprehensive relativistic Boltzmann analysis including quantum corrections and exact QED matrix elements for all relevant interactions.

Findings

Binary interactions dominate in non-relativistic regime, leading to kinetic equilibrium.

Triple interactions are crucial in relativistic regime, preventing kinetic equilibrium.

Quantum degeneracy significantly influences the thermalization process.

Abstract

The non-equilibrium electron-positron-photon plasma thermalization process is studied using relativistic Boltzmann solver, taking into account quantum corrections both in non-relativistic and relativistic cases. Collision integrals are computed from exact QED matrix elements for all binary and triple interactions in the plasma. It is shown that in non-relativistic case (temperatures $k_B T\leq 0.3 m_e c^2$) binary interaction rates dominate over triple ones, resulting in establishment of the kinetic equilibrium prior to final relaxation towards the thermal equilibrium, in agreement with the previous studies. On the contrary, in relativistic case (final temperatures $k_B T\geq 0.3 m_e c^2$) triple interaction rates are fast enough to prevent the establishment of kinetic equilibrium. It is shown that thermalization process strongly depends on quantum degeneracy in initial state, but does not depend on plasma composition.