Determination of transport coefficients by coronal seismology of flare-induced slow-mode waves: Numerical parametric study of 1D loop model

TL;DR

This paper develops a new coronal seismology method to determine transport coefficients in hot plasma loops by analyzing wave properties, revealing suppression of thermal conduction and enhancement of viscosity during a solar flare event.

Contribution

The study introduces a two-step seismology technique to quantify thermal conduction suppression and viscosity enhancement in flaring loops using 1D MHD modeling and observational data.

Findings

Thermal conduction is suppressed by a factor of about 3.

Viscosity is enhanced by a factor of 10.

The method accurately reproduces observed wave excitation times.

Abstract

Recent studies of a flaring loop oscillation event on 2013 December 28 observed by the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO) have revealed the suppression of thermal conduction and significant enhancement of compressive viscosity in hot ($\sim$10 MK) plasma. In this study we aim at developing a new coronal seismology method for determining the transport coefficients based on a parametric study of wave properties using a 1D nonlinear MHD loop model in combination with the linear theory. The simulations suggest a two-step scheme: we first determine the effective thermal conduction coefficient from the observed phase shift between temperature and density perturbations as this physical parameter is insensitive to the unknown viscosity; then from the loop model with the obtained thermal conduction coefficient, we determine the effective viscosity coefficient from the observed decay time using the parametric modeling. With this new seismology technique we are able to quantify the suppression of thermal conductivity by a factor of about 3 and the enhancement of viscosity coefficient by a factor of 10 in the studied flaring loop. Using the loop model with these refined transport coefficients, we study the excitation of slow magnetoacoustic waves by launching a flow pulse from one footpoint. The simulation can self-consistently produce the fundamental standing wave on a timescale in agreement with the observation.