A search for evidence of solar rotation in Super-Kamiokande solar neutrino dataset

TL;DR

This study applies advanced periodogram analysis to Super-Kamiokande solar neutrino data to search for evidence of solar rotation, confirming a peak at 9.42/year but with marginal significance, indicating the need for more data.

Contribution

It introduces a combined statistical approach using Lomb-Scargle periodogram, bootstrap FAP, and BIC to evaluate potential solar rotation signals in neutrino data.

Findings

Peak at 9.42/year confirmed, corresponding to 38.75 days.

Significance of the peak is marginal, with FAP around 1.5%.

More data needed to confirm the persistence of the signal.

Abstract

We apply the generalized Lomb-Scargle (LS) periodogram, proposed by Zechmeister and Kurster, to the solar neutrino data from Super-Kamiokande (Super-K) using data from its first five years. For each peak in the LS periodogram, we evaluate the statistical significance in two different ways. The first method involves calculating the False Alarm Probability (FAP) using non-parametric bootstrap resampling, and the second method is by calculating the difference in Bayesian Information Criterion (BIC) between the null hypothesis, viz. the data contains only noise, compared to the hypothesis that the data contains a peak at a given frequency. Using these methods, we scan the frequency range between 7-14 cycles per year to look for any peaks caused by solar rotation, since this is the proposed explanation for the statistically significant peaks found by Sturrock and collaborators in the Super-K dataset. From our analysis, we do confirm that similar to Sturrock et al, the maximum peak occurs at a frequency of 9.42/year, corresponding to a period of 38.75 days. The FAP for this peak is about 1.5% and the difference in BIC (between pure white noise and this peak) is about 4.8. We note that the significance depends on the frequency band used to search for peaks and hence it is important to use a search band appropriate for solar rotation. However, the significance of this peak based on the value of BIC is marginal and more data is needed to confirm if the peak persists and is real.