Scaler rates from the Pierre Auger Observatory: a new proxy of solar activity

Abstract

The modulation of low-energy galactic cosmic rays reflects interplanetary magnetic field variations and can provide useful information on solar activity. An array of ground-surface detectors can reveal the secondary particles, which originate from the interaction of cosmic rays with the atmosphere. In this work, we present an investigation of the low-threshold rate (scaler) time series recorded in 16 years of operation by the Pierre Auger Observatory surface detectors in Malargue, Argentina. Through an advanced spectral analysis, we detected highly statistically significant variations in the time series with periods ranging from the decadal to the daily scale. We investigate their origin, revealing a direct connection with solar variability. Thanks to their intrinsic very low noise level, the Auger scalers allow a thorough and detailed investigation of the galactic cosmic-ray flux variations in the heliosphere at different timescales and can, therefore, be considered a new proxy of solar variability.

arXiv comment18 pages, 5 figures, accepted for publication in The Astrophysical Journal

References in corpus (18)

• The Pierre Auger Cosmic Ray Observatory
• Solar Modulation of Cosmic Rays
• The Surface Detector System of the Pierre Auger Observatory
• Magnetic Rossby waves in the solar tachocline and Rieger-type periodicities
• Rossby waves in "shallow water" magnetohydrodynamics
• Calibration of the Surface Array of the Pierre Auger Observatory
• The Search for the Sidereal and Solar Diurnal Modulations in the Total MACRO Muon Data Set
• Rieger-type periodicity during solar cycles 14-24: estimation of dynamo magnetic field strength in the solar interior
• The behaviour of galactic cosmic ray intensity during solar activity cycle 24
• Solar Energetic Particle Spectrum on 13 December 2006 Determined by IceTop
• An Analysis of Apparent r-Mode Oscillations in Solar Activity, the Solar Diameter, the Solar Neutrino Flux, and Nuclear Decay Rates, with Implications Concerning the Solar Internal Structure and Rotation, and Neutrino Processes
• The scaler mode in the Pierre Auger Observatory to study heliospheric modulation of cosmic rays
• Magneto-Rossby waves in the solar tachocline and the annual variations in solar activity
• Reconstruction of Events Recorded with the Surface Detector of the Pierre Auger Observatory
• Indications of r-mode Oscillations in SOHO/MDI Solar Radius Measurements
• Recurrence of galactic cosmic rays intensity and anisotropy in solar minima 23/24 and 24/25 by ACE/CRIS, STEREO, SOHO/EPHIN and neutron monitors. Fourier and wavelet analysis. Dedicated to the Memory of Michael Alania
• Differential rotation of the solar corona: A new data-adaptive multiwavelength approach
• Analytic modeling of recurrent Forbush decreases caused by corotating interaction regions