Newly-Discovered Anomalies in Galactic Cosmic Rays: Time for Exotic Scenarios?

Abstract

Recent observations of galactic cosmic rays (CR) in the 1-500 GeV energy range have revealed striking deviations from what deemed "standard." The anomalies cut across hadronic and leptonic CRs. I discuss findings that challenge physical mechanisms long held responsible for the CR production in galactic supernova remnants (SNR). I also consider some new physics of particle acceleration in SNR shocks that is not part of conventional models but may explain the anomalies. However, a possible 20-30\% excess remains unaccounted for in the $e^{+}/e^{+}$ ratio over the range of a few 100 GeV. If not explained by future models, it suggests an additional source of positrons such as a dark matter decay/annihilation or pulsar contribution. Earlier efforts to explain both the $e^{+}/e^{-}$ and $p$/He anomalies with the "standard" models by adjusting the SNR environmental parameters and multiple sources are critically assessed.

Cosmic Rays beyond the Standard Model, San Vito, 2016, http://www.crbtsm.eu/, conference paper

References in corpus (11)

• Observation of an anomalous positron abundance in the cosmic radiation
• A Theory of Dark Matter
• Cosmic-Ray Proton and Helium Spectra from the First CREAM Flight
• The origin of the positron excess in cosmic rays
• Simulations and Theory of Ion Injection at Non-relativistic Collisionless Shocks
• Testing astrophysical models for the PAMELA positron excess with cosmic ray nuclei
• The origin of cosmic rays: Explosions of massive stars with magnetic winds and their supernova mechanism
• Cosmic Ray Origins: An Introduction
• Origin of the Proton-to-Helium Ratio Anomaly in Cosmic Rays
• Plus Charge Prevalence in Cosmic Rays: Room for Dark Matter in the Positron Spectrum
• On the Structure and Scale of Cosmic Ray Modified Shocks

Cited by in corpus (4)

• Cosmic ray production in supernovae
• On the origin of observed cosmic ray spectrum below 100 TV
• Cosmic Ray Spectrum Steepening in Supernova Remnants -- I. Loss-Free Self-Similar Solution
• Steepening of Cosmic Ray Spectra in Shocks with Varying Magnetic Field Direction