What Can DKIST/DL-NIRSP Tell Us About Quiet-Sun Magnetism?

TL;DR

This study evaluates DKIST/DL-NIRSP's ability to diagnose quiet-Sun magnetism by synthesizing and analyzing high-resolution spectropolarimetric data, revealing the potential and limitations in estimating magnetic energy fluxes.

Contribution

The paper demonstrates the effectiveness of DL-NIRSP in estimating large-scale velocity fields and Poynting flux in quiet-Sun regions using realistic simulations and assesses the impact of observational parameters.

Findings

Unsigned Poynting flux estimates account for over 50% of the true flux.

Net Poynting flux is significantly underestimated, mainly due to horizontal motion underestimation.

Velocity estimation accuracy depends on temporal resolution.

Abstract

Quiet-Sun regions cover most of the Sun's surface; its magnetic fields contribute significantly to the solar chromospheric and coronal heating. However, characterizing the magnetic fields of the quiet Sun is challenging due to their weak polarization signal. The 4-m \textit{Daniel K. Inouye Solar Telescope} (\textit{DKIST}) is expected to improve our understanding of the quiet-Sun magnetism. In this paper, we assess the diagnostic capability of the Diffraction-Limited Near Infrared Spectropolarimeter (DL-NIRSP) instrument on \textit{DKIST} on the energy transport processes in the quiet-Sun photosphere. To this end, we synthesize high-resolution, high-cadence Stokes profiles of the \ion{Fe}{1} 630~nm lines using a realistic magnetohydrodynamic simulation, degrade them to emulate the \textit{DKIST}/DL-NIRSP observations, and subsequently infer the vector magnetic and velocity fields. For the assessment, we first verify that a widely used flow-tracking algorithm, Differential Affine Velocity Estimator for Vector Magnetograms, works well for estimating the large-scale ($> 200$ km) photospheric velocity fields with these high-resolution data. We then examine how the accuracy of inferred velocity depends on the temporal resolution. Finally, we investigate the reliability of the Poynting flux estimate and its dependence on the model assumptions. The results suggest that the unsigned Poynting flux, estimated with existing schemes, can account for about $71.4\%$ and $52.6\%$ of the reference ground truth at $\log \tau =0.0$ and $\log \tau = -1$. However, the net Poynting flux tends to be significantly underestimated. The error mainly arises from the underestimated contribution of the horizontal motion. We discuss the implications on \textit{DKIST} observations.