Annihilation of positrons from $^{22}$Na in novae

TL;DR

This paper investigates how magnetic fields in novae affect the escape and annihilation of positrons from $^{22}$Na, revealing that strong magnetic fields can prolong the 511 keV emission significantly.

Contribution

It is the first study to analyze the impact of magnetic fields on positron escape and annihilation flux evolution in novae.

Findings

Magnetic fields of about 10^6 G can significantly impede positron escape.

Strong magnetic fields can extend the duration of 511 keV emission to hundreds of days.

Magnetic effects are crucial for understanding nova gamma-ray signals.

Abstract

We explore for the first time effects of the magnetic field on the escape of $^{22}$Na positrons and on the flux evolution of annihilation 511 keV line in novae. It is shown that for the white dwarf magnetic field of $\sim 10^6$ G the field of the expanding nova shell is able to significantly impede positrons escape and increase the time of the nova emission in 511keV up to hundreds days.