On the solar origin of the signal at 220.7microHz: A possible component of a g mode?

TL;DR

This study investigates a persistent signal at 220.7 microHz in helioseismic data, providing evidence it originates from the Sun and may be linked to a g-mode component, advancing understanding of solar internal oscillations.

Contribution

The paper presents the first analysis confirming the solar origin of the 220.7 microHz signal and its potential as a g-mode component, using multi-instrument data and statistical validation.

Findings

The 220.7 microHz signal is unlikely to be instrumental noise.

The signal has a solar origin based on VIRGO and SoHO data.

Monte Carlo simulations confirm the signal's significance at over 99% confidence.

Abstract

Gravity modes in the Sun have been the object of a long and difficult search in recent decades. Thanks to the data accumulated with the last generation of instruments (BiSON, GONG and three helioseismic instruments aboard SoHO), scientists have been able to find signatures of their presence. However, the individual detection of such modes remains evasive. In this article, we study the signal at 220.7 microHz which is a peak that is present in most of the helioseismic data of the last 10 years. This signal has already been identified as being one component of a g-mode candidate detected in the GOLF Doppler velocity signal. The nature of this peak is studied in particular using the VIRGO/SPM instrument aboard SoHO. First we analyse all the available instrumental data of VIRGO and SoHO (housekeeping) to reject any possible instrumental origin. No relation was found, implying that the signal has a solar origin. Using Monte Carlo simulations, we find, with more than 99% confidence level, that the signal found in VIRGO/SPM is very unlikely to be due to pure noise.