Extracting the size of the cosmic electron-positron anomaly

TL;DR

This paper uses Bayesian analysis of cosmic ray data to identify and quantify an anomalous electron-positron component, revealing a significant deviation from background predictions and suggesting a potential new physics signal.

Contribution

The study introduces a Bayesian likelihood method to isolate the cosmic electron-positron anomaly and quantifies its size within a propagation model framework.

Findings

Detected a significant deviation in electron-positron fluxes from background predictions.

Identified the anomalous component as a potential new physics signal.

Compared the anomaly with theoretical models predicting such excesses.

Abstract

We isolated the anomalous part of the cosmic electron-positron flux within a Bayesian likelihood analysis. Using 219 recent cosmic ray spectral data points, we inferred the values of selected cosmic ray propagation parameters. In the context of the propagation model coded in GalProp, we found a significant tension between the electron positron related and the rest of the fluxes. Interpreting this tension as the presence of an anomalous component in the electron-positron related data, we calculated background predictions for PAMELA and Fermi-LAT based on the non-electron-positron related fluxes. We found a deviation between the data and the predicted background even when uncertainties, including systematics, were taken into account. We identified this deviation with the anomalous electron-positron contribution. We briefly compared this model independent signal to some theoretical results predicting such an anomaly.