Extreme Plasmas Near Pulsars and Strange Stars

Abstract

Pulsars are fast rotating neutron stars with extremely strong magnetic fields (∼ 109 – 1013 G) at their surface. Current models for the generation of coherent radio emission of pulsars require formation of electron‐positron pairs in pulsar magnetospheres. Such pair plasma may be created via conversion of γ‐rays into electron‐positron pairs in a strong magnetic field. Generation of γ‐rays and creation of pair plasma in the magnetospheres of pulsars are discussed. Plasma instabilities in the magnetized pair plasma are reviewed. Bare strange stars, which are entirely made of deconfined quarks, may be extremely powerful sources of pair plasma. In this case, electron‐positron pairs are created in a thin layer with a very strong electric field at the quark surface. The luminosity of a bare strange star in pairs is a function of the surface temperature, and it may be as high as ∼ 1051 – 1052 ergs s−1 at the moment of the strange star formation when the surface temperature may be ∼ a few × 1010 K or even higher. Creation of electron‐positron pairs at the surface of bare strange stars and physical processes in the outflowing pair plasma are discussed.