Gamma-ray emission from strongly magnetized pulsars

TL;DR

This paper explores how strong magnetic fields in pulsars lead to the formation of bound electron-positron pairs, significantly increasing gamma-ray emission and potentially explaining observed luminosities.

Contribution

It introduces a model where bound pair creation in strong magnetic fields enhances gamma-ray emission from pulsars, differing from conventional free pair models.

Findings

Bound pairs do not screen electric fields, increasing energy output.

Modified polar gap power can match observed gamma-ray luminosities.

The process may account for a substantial fraction of pulsar spin-down power.

Abstract

In a strong magnetic field, B > 4x10^{12} G, gamma-rays emitted nearly along curved field lines adiabatically convert into bound electron-positron pairs (positronium atoms) rather that decaying into free pairs. This process may modify the polar gaps of strong magnetized pulsars. Unlike free pairs, such bound pairs do not screen the electric field component along the magnetic field in the polar gaps. As a result the total power carried away by both relativistic particles and radiation, from the polar gap into the pulsar magnetosphere, may increase significantly (up to a few tens times) in comparison with the conventional polar gap models where creation of bound pairs is ignored, and it may be a substantial fraction of the spin-down power. We demonstrate that the total power of the modified polar gaps may be enough to explain the observed non-thermal luminosities of all known strongly magnetized, gamma-ray pulsars.