Impact of low-frequency p modes on the inversions of the internal rotation of the Sun

TL;DR

This study analyzes how low-frequency solar p-mode data, obtained via the collapsogram technique from GONG and MDI observations, influence the accuracy of inverting the Sun's internal rotation profile.

Contribution

It introduces the use of the collapsogram method to measure low-frequency p-mode parameters and assesses their impact on solar rotation inversions.

Findings

Low-frequency p-modes can be reliably measured down to ~850 μHz.

Including low-frequency modes affects the inversion results of the Sun's internal rotation.

Differences between GONG and MDI data influence the inversion outcomes.

Abstract

We used the m-averaged spectrum technique ("collapsogram") to extract the low-frequency solar p-mode parameters of low- and intermediate-angular degrees (l \leq 35) in long time series of GONG and MDI observations. Rotational splittings and central frequencies have been measured down to ~850\muHz, including predicted modes which have not been measured previously. Both GONG and MDI frequency splitting data sets were numerically inverted to extract the internal solar rotation rate. The impact of the very low-frequency observables and the differences between GONG and MDI data sets on the inversion results are also analyzed.