Astrophysical models for the origin of the positron "excess"

TL;DR

This paper reviews astrophysical models explaining the positron excess observed in cosmic ray spectra, summarizing data, proposed explanations, and future testing prospects.

Contribution

It provides a comprehensive overview of current astrophysical explanations for the positron excess and discusses future experimental tests.

Findings

Summary of cosmic ray positron data features

Comparison of different astrophysical models

Discussion of future observational diagnostics

Abstract

Over the last three years, several satellite and balloon observatories have suggested intriguing features in the cosmic ray lepton spectra. Most notably, the PAMELA satellite has suggested an "anomalous" rise with energy of the cosmic ray positron fraction. In this article, we summarize the global picture emerging from the data and recapitulate the main features of different types of explanations proposed. The perspectives in testing different scenarios as well as inferring some astrophysical diagnostics from current/near future experiments are also discussed.