Semi-analytical model of cosmic ray electron transport

TL;DR

This paper extends an analytical cosmic ray electron transport model to better understand the leptonic spectrum in the galaxy, explaining observed anomalies with additional sources and providing constraints on the interstellar medium.

Contribution

It introduces a numerical extension to an existing analytical model, incorporating secondary and additional symmetric sources to explain cosmic ray electron observations.

Findings

Secondary production alone cannot explain PAMELA and Fermi data.

An additional symmetric source of e+ and e- is necessary.

The model constrains properties of the interstellar medium.

Abstract

We present a numerical extension to the analytical propagation model introduced in Hein and Spanier (2008) to describe the leptonic population in the galactic disc. The model is used to derive a possible identification of the components that contribute to the leptonic cosmic ray spectrum, as measured by PAMELA, Fermi and HESS, with an emphasis on secondary e+ - e- production in collisions of cosmic ray particles with ambient interstellar medium (ISM). We find that besides secondaries, an additional source symmetric in e+ and e- production is needed to explain both the PAMELA anomaly and the Fermi bump, assuming a power-law primary electron spectrum. Our model also allows us to derive constraints for some properties of the ISM.