Bonn 2020 – scientific programme
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T: Fachverband Teilchenphysik
T 29: Cosmic rays I
T 29.4: Talk
Tuesday, March 31, 2020, 17:45–18:00, H-HS XII
The cosmic-ray shadow of the Sun and its temporal variation - lessons learned from simulations — •Julia Becker Tjus1, Paolo Desiati2, Niklas Döpper1, Horst Fichtner1, Jens Kleimann1, and Frederik Tenholt1 — 1Theoretische Physik IV, Ruhr-Universität Bochum, 44780 Bochum — 2UW Madison, Wisconsin, USA
While cosmic rays show a high level of isotropy when they arrive at Earth, two sinks have been identified by different observatories: the Moon and the Sun. Moon shadow measurements, on the one hand, are typically used for pointing calibrations and angular resolution estimates of the instruments. The Sun shadow, on the other hand, has been shown to change with time, revealing a correlation with the 22-year cycle of the solar magnetic activity and, in turn, the solar magnetic field.
In this contribution, we present simulations of the cosmic-ray Sun shadow for which we apply a back-tracking approach for the particle propagation around the Sun. We show how the shadow projected at Earth changes with time. In addition, we investigate the energy dependence of the depth of the shadow. We show that it changes significantly when comparing years of low solar activity to those of high solar activity. We discuss the implications for future measurements with cosmic-ray detectors and the physics to be learned from such measurements.