Bonn 2020 – scientific programme

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T: Fachverband Teilchenphysik

T 29: Cosmic rays I

T 29.3: Talk

Tuesday, March 31, 2020, 17:30–17:45, H-HS XII

Comparing the Cosmic-Ray Sun Shadow in Seven Years of IceCube Data with the Solar Cycle and Solar Magnetic Field Models — Frederik Tenholt, Julia Becker Tjus, and •Johan Wulff for the IceCube collaboration — Theoretische Physik IV, Ruhr-Universität Bochum, 44780 Bochum

Measuring the temporal variation of the cosmic-ray Sun shadow has been shown to be a useful tool for assessing different solar magnetic field models.

In this talk, seven years of IceCube data are compared to solar activity and solar magnetic field models. For the first time, such models have been compared quantitatively to IceCube data on the event rate level. Moreover, the energy-dependence of the Sun shadow in IceCube has been studied for the first time and is compared to recent predictions.

Using the sunspot number as an indicator of solar activity, an anti-correlation between Sun shadow strength and solar activity is found to be likely. By modeling cosmic-ray propagation in the solar magnetic field and comparing the predicted Sun shadow to the measured one, two different models of the coronal magnetic field are tested. In agreement with the data, both models predict a weakening of the shadow in times of high solar activity. Assuming only statistical uncertainties, however, tensions on the order of 3 σ remain. In times of high solar activity, there is a small indication that the shadowing effect increases with increasing cosmic-ray energy, which is in agreement with a recent prediction.