Cosmic Ray Electrons, Positrons and the Synchrotron emission of the Galaxy: consistent analysis and implications

TL;DR

This paper performs a comprehensive analysis of cosmic ray electrons, positrons, and galactic synchrotron emission to understand their sources, propagation, and implications for dark matter, revealing a suppressed low-energy electron spectrum and constraining cosmic-ray distribution height.

Contribution

It provides a consistent multichannel analysis using the DRAGON code, constrains the interstellar electron spectrum, and sets limits on the cosmic-ray scale height, impacting dark matter research.

Findings

Electron source spectrum is a power-law with index -2.5 above 4 GeV.

Below 4 GeV, the spectrum is suppressed and dominated by secondary particles.

The cosmic-ray scale height is constrained to be greater than 2 kpc.

Abstract

A multichannel analysis of cosmic ray electron and positron spectra and of the diffuse synchrotron emission of the Galaxy is performed by using the DRAGON code. This study is aimed at probing the interstellar electron source spectrum down to E ~ 1 GeV and at constraining several propagation parameters. We find that above 4 GeV the electron source spectrum is compatible with a power-law of index -2.5. Below 4 GeV instead it must be significantly suppressed and the total lepton spectrum is dominated by secondary particles. The positron spectrum and fraction measured below a few GeV are consistently reproduced only within low reacceleration models. We also constrain the scale-height zt of the cosmic-ray distribution using three independent (and, in two cases, original) arguments, showing that values of z_t < 2 kpc are excluded. This result may have strong implications for particle dark matter searches.