Positron excess in the center of the Milky Way from short-lived $\beta^+$ emitting isotopes

TL;DR

This paper suggests that short-lived positron-emitting isotopes produced by cosmic ray interactions could significantly explain the observed 511 keV gamma-ray excess in the Milky Way's center.

Contribution

It introduces a novel explanation for the positron excess involving extsuperscript{pos}-emitting isotopes from cosmic ray interactions, which was not previously considered.

Findings

extsuperscript{pos}-emitting isotopes can account for up to several tens of percent of positron production.

The proposed mechanism provides a plausible source for the observed gamma-ray excess.

Cosmic ray interactions with light nuclei are a significant contributor to positron production in the galactic center.

Abstract

Observations of the INTEGRAL satellite revealed the presence of yet unexplained excess in the central region of the Galaxy at the energies around 511 keV. These gamma-rays are produced in the process of positron annihilation, the needed rate is around $10^{42}~\mathrm{s^{-1}}$. In this short paper it is shown that \pos -emitting isotopes that are formed in interactions of subrelativistic cosmic rays (CRs) with light nuclei (CNONe) can account for a considerable fraction -- up to several tens of percent -- of $e^{+}$ production rate in the central region.