Characteristics of acoustic-wave heating in simulations of the quiet Sun chromosphere

TL;DR

This study uses 3D radiative MHD simulations to analyze how acoustic waves dissipate energy and contribute to heating the quiet Sun chromosphere, highlighting the importance of wave steepening and shock formation.

Contribution

It provides a detailed analysis of acoustic wave dissipation characteristics and their role in chromospheric heating, including the dependence on height and magnetic field configuration.

Findings

Acoustic waves with frequencies near the cut-off efficiently heat the chromosphere.

Wave steepening into shocks occurs at specific heights and frequencies.

Propagating wave flux correlates with viscous dissipation.

Abstract

Understanding energy transfer through the chromosphere is paramount to solving the coronal heating problem. We investigated the energy dissipation of acoustic waves in the chromosphere of the quiet Sun using 3D radiative magnetohydrodynamic (rMHD) simulations. We analysed the characteristics of acoustic-wave heating and its dependence on height and magnetic field configuration. We find the typical heights where acoustic waves steepen into shocks and the frequencies and wavenumbers that most efficiently dissipate wave energy through this steepening. We combined a comprehensive large-scale analysis, spanning the entirety of the simulations for several solar hours, with a detailed view of an individual shock. We find that the flux of propagating acoustic waves correlates closely with viscous dissipation in the chromosphere above the temperature minimum. Acoustic waves with frequencies close to the acoustic cut-off frequency can efficiently heat the quiet Sun chromosphere at the plasma-$\beta$ = 1 interface and play an important role in the chromospheric energy balance.