Evidence for a Time Lag in Solar Modulation of Galactic Cosmic Rays

Abstract

The solar modulation effect of cosmic rays in the heliosphere is an energy-, time-, and particle-dependent phenomenon which arises from a combination of basic particle transport processes such as diffusion, convection, adiabatic cooling, and drift motion. Making use of a large collection of time-resolved cosmic-ray data from recent space missions, we construct a simple predictive model of solar modulation which depends on direct solar-physics inputs: the number of solar sunspots and the tilt angle of the heliospheric current sheet. Under this framework, we present calculations of cosmic-ray proton spectra, positron/electron and antiproton/proton ratios and their time dependence in connection with the evolving solar activity. We report evidence for a time-lag $\Delta T=8.1\pm 1.2$ months, between solar activity data and cosmic-ray flux measurements in space, which reflects the dynamics of the formation of the modulation region. This result enables us to forecast the cosmic-ray flux near Earth well in advance by monitoring solar activity

Published as gold open access in ApJ Letters

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Cited by in corpus (20)

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• HelMod in the works: from direct observations to the local interstellar spectrum of cosmic-ray electrons
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• Testing diffusion of cosmic rays in the heliosphere with proton and helium data from AMS
• Numerical modeling of cosmic rays in the heliosphere: Analysis of proton data from AMS-02 and PAMELA
• Studies on cosmic ray nuclei with Voyager, ACE and AMS-02: I. local interstellar spectra and solar modulation
• Time and Charge-Sign Dependence of the Heliospheric Modulation of Cosmic Rays
• Dark Matter Search in Space: Combined Analysis of Cosmic Ray Antiproton-to-Proton Flux Ratio and Positron Flux Measured by AMS-02
• Numerical modeling of cosmic-ray transport in the heliosphere and interpretation of the proton-to-helium ratio in Solar Cycle 24
• Temporal evolution and rigidity dependence of the solar modulation lag of Galactic cosmic rays
• Local interstellar spectra and solar modulation of cosmic ray electrons and positrons
• Modulation of cosmic ray anti-protons in the heliosphere: simulations for a solar cycle
• Data driven analysis of cosmic rays in the heliosphere: diffusion of cosmic protons
• Galactic Cosmic Rays at Mars and Venus: Temporal Variations from Hours to Decades Measured as the Background Signal of Onboard Micro-Channel Plates
• Observation of a time lag in solar modulation of cosmic rays in the heliosphere
• Propagation Times and Energy Losses of Cosmic Protons and Antiprotons in Interplanetary Space
• Puzzling Variation of Gamma Rays from the Sun over the Solar Cycle Revealed with Fermi-LAT
• Solar modulation of cosmic proton and helium with AMS-02
• Temporal Correlation between Positive-Charged Cosmic Ray Flux and Solar Polar Field Variation: Insights from Delayed Modulation Analysis
• Precision measurement of the cosmic-ray electron and positron fluxes as a function of time and energy with the Alpha Magnetic Spectrometer on the International Space Station