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

TL;DR

This study uses a decade of ANTARES neutrino telescope data to observe the Sun's cosmic ray shadow, confirming the detector's angular resolution and pointing accuracy with a statistical significance of 3.7 sigma.

Contribution

It provides the first detailed analysis of the Sun shadow effect with ANTARES data, validating the detector's performance and calibration methods.

Findings

Sun shadow observed with 3.7 sigma significance

Angular resolution estimated at 0.59 degrees

No systematic pointing shift detected

Abstract

ANTARES is the largest undersea neutrino telescope and it has been taking data in its final configuration for more than ten years. On their journey to the Earth, cosmic rays can be absorbed by celestial objects, like the Sun, leading to a deficit in the atmospheric muon flux measured by the ANTARES detector, 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 $3.7\sigma$ and the estimated angular resolution value of the ANTARES telescope for downward-going muons is $0.59^{\circ} \pm 0.10^{\circ}$, which 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 consistent with the expectations.