"Discrepant hardenings" in cosmic ray spectra: a first estimate of the effects on secondary antiproton and diffuse gamma-ray yields

TL;DR

Recent cosmic ray data suggest spectral hardening at TeV energies, which significantly impacts secondary antiproton and gamma-ray yields, affecting astrophysical models and dark matter search backgrounds.

Contribution

This study provides the first estimate of how spectral hardening in cosmic rays alters secondary particle production, highlighting the importance of intrinsic spectral features.

Findings

Spectral modifications cause ~30% increase in antiproton flux near 1 TeV.

Diffuse gamma-ray yields can increase by similar factors at ~300 GeV.

Implications for astrophysical parameter estimation and dark matter background modeling.

Abstract

Recent data from CREAM seem to confirm early suggestions that primary cosmic ray (CR) spectra at few TeV/nucleon are harder than in the 10-100 GeV range. Also, helium and heavier nuclei spectra appear systematically harder than the proton fluxes at corresponding energies. We note here that if the measurements reflect intrinsic features in the interstellar fluxes (as opposed to local effects) appreciable modifications are expected in the sub-TeV range for the secondary yields, such as antiprotons and diffuse gamma-rays. Presently, the ignorance on the origin of the features represents a systematic error in the extraction of astrophysical parameters as well as for background estimates for indirect dark matter searches. We find that the spectral modifications are appreciable above 100 GeV, and can be responsible for ~30% effects for antiprotons at energies close to 1 TeV or for gamma's at energies close to 300 GeV, compared to currently considered predictions based on simple extrapolation of input fluxes from low energy data. Alternatively, if the feature originates from local sources, uncorrelated spectral changes might show up in antiproton and high-energy gamma-rays, with the latter ones likely dependent from the line-of-sight.