Secondary Production as the Origin for the Cosmic Ray Positron Excess

TL;DR

This paper proposes that the observed cosmic ray positron excess can be explained by secondary production processes, without invoking dark matter or exotic mechanisms, supported by a new propagation scenario consistent with observations.

Contribution

It introduces a novel cosmic ray propagation scenario based on recent astrophysical data, demonstrating that secondary production accounts for the positron excess.

Findings

The scenario matches observed positron flux data.

Secondary production explains the excess without dark matter.

The approach is consistent across heuristic and diffusion-reacceleration models.

Abstract

The Alpha Magnetic Spectrometer has released high-precision data for cosmic rays, and has verified an excess of positrons relative to expectations from cosmic ray interactions in the interstellar medium. An exciting and well-known possibility for the excess is production of electron-positron pairs by annihilating dark matter particles in the halo of the Galaxy. We have constructed a new scenario for propagation of cosmic rays, based on the 2000 SMILI results and various other astrophysics observations and measurements, in which the positron excess is due to secondary production. The scenario is studied from a simple heuristic perspective, and also within the constraints of a diffusion-reacceleration model using GALPROP. The conclusions of each approach agree with one another, showing that the scenario agrees well with the observed positron flux, without any need for dark matter or other exotic production mechanisms.