Identifying Acoustic Wave Sources on the Sun. II. Improved Filter Techniques for Source Wavefield Seismology

TL;DR

This paper enhances an acoustic-source filter for helioseismology, enabling precise detection of wavefronts and source depths, which allows detailed 3D imaging of subsurface solar structures on very small scales.

Contribution

The paper introduces an improved filter technique that refines source discrimination and depth estimation, advancing ultra-local helioseismic analysis capabilities.

Findings

Robust 3D helioseismic inversions for subsurface flows and sound speed are achievable.

Filter refinement allows discrimination of acoustic-source depths.

Demonstrated effectiveness using MURaM simulation data.

Abstract

In this paper we refine a previously developed acoustic-source filter (Bahauddin & Rast 2021), improving its reliability and extending its capabilities. We demonstrate how to fine-tune the filter to meet observational constraints and to focus on specific wavefront speeds. This refinement enables discrimination of acoustic-source depths and tracking of local-source wavefronts, thereby facilitating ultra-local helioseismology on very small scales. By utilizing the photospheric Doppler signal from a subsurface source in a MURaM simulation, we demonstrate that robust ultra-local three-dimensional helioseismic inversions for the granular flows and sound speed to depths of at least 80 km below the photosphere are possible. The capabilities of the National Science Foundation's new Daniel K. Inouye Solar Telescope (DKIST) will enable such measurements of the real Sun.