The cosmic $e^\pm$ anomaly

TL;DR

This paper uses Bayesian analysis of cosmic ray data to identify and characterize an anomalous electron-positron flux component, revealing a significant deviation from background predictions and exploring potential sources.

Contribution

It introduces a method to extract the anomalous cosmic $e^$ flux and assesses its origin, providing new insights into cosmic ray anomalies.

Findings

Significant tension between $e^$ flux and other cosmic ray data.

Detected a statistically significant excess in Fermi-LAT $e^-+e^+$ data.

Proposed potential sources for the anomalous $e^$ flux.

Abstract

Via a Bayesian likelihood analysis using 219 recent cosmic ray spectral data points we extract the anomalous part of the cosmic $e^\pm$ flux. First we show that a significant tension exists between the $e^\pm$ related and the rest of the fluxes. Interpreting this tension as the presence of an anomalous component in the $e^\pm$ related data, we then infer the values of selected cosmic ray propagation parameters excluding the anomalous data sample from the analysis. Based on these values we calculate background predictions with theoretical uncertainties for PAMELA and Fermi-LAT. We find a statistically significant deviation between the Fermi-LAT $e^-+e^+$ data and the predicted background even when (systematic) uncertainties are taken into account. Identifying this deviation as an anomalous $e^\pm$ contribution, we make an attempt to distinguish between various sources that may be responsible for the anomalous $e^\pm$ flux.