Observation of the cosmic ray shadow of the Sun with the ANTARES neutrino telescope

The ANTARES neutrino telescope is operating in the Mediterranean Sea in its full configuration since 2008. On their journey to the Earth, cosmic rays (CRs) can be absorbed by celestial objects, like the Sun, leading to a deficit in atmospheric muons produced by CR interactions from the solid angle region covered by the Sun, the so-called Sun “shadow” effect. This phenomenon can be used to evaluate fundamental telescope characteristics: the detector angular resolution and pointing accuracy. This work describes the study of the Sun “shadow” effect using the ANTARES data collected between 2008 and 2017. The statistical significance of the Sun shadow observation is 3.7σ and the estimated angular resolution value of the ANTARES telescope for downward-going muons is 0.59◦ ± 0.10◦. This result is consistent with the expectations obtained from the Monte Carlo simulations and also with the estimation from the Moon "shadow" analysis of 2007-2016 years. No evidence of systematic pointing shift is found and the resulting pointing accuracy is in agreement with the expectations.