Thermodynamic Evolution of Flaring Loops with Non-local Thermal Transport

TL;DR

This study compares classical, flux-limited, and non-local thermal transport models in simulating flaring solar coronal loops, revealing that non-local models like SNB produce more realistic, hotter, and less dense loop evolutions with distinct observational signatures.

Contribution

It introduces the application of the SNB non-local thermal transport model to solar flare loop simulations, demonstrating its differences from classical and flux-limited models and emphasizing its importance for realistic modeling.

Findings

SNB model yields higher temperatures and lower densities in loops.

Non-local transport produces more localized and intense temperature peaks.

Flare light curves are smoother with lower peak amplitudes in SNB simulations.

Abstract

Hot solar coronal loops, such as flaring loops, reach temperatures where the thermal transport becomes non-local. This occurs when the mean-free-path of electrons can no longer be assumed to be small. Using a modified version of the Lare2d code, we study the evolution of flare-heated coronal loops under three thermal transport models: classical Spitzer-Harm (SH), a flux-limited local model (FL), and the non-local Schurtz-Nicolai-Basquet (SNB) model. The SNB model is used extensively in laser-plasma studies. It has been benchmarked against accurate non-local Vlasov-Fokker-Planck models and proven to be the most accurate non-local model which can be applied on fluid time-scales. Analysis of the density-temperature evolution cycles near the loop apex reveals a distinct evolutionary path for the SNB model, with higher temperatures and lower densities than local models. During energy deposition, the SNB model produces a more localised and intense temperature peak at the apex due to heat flux suppression, which also reduces chromospheric evaporation and results in lower post-flare densities. EUV emission synthesis shows that the SNB model yields flare light curves with lower peak amplitudes and smoother decay phases. We also find that non-local transport affects equilibrium loop conditions, producing hotter and more rarefied apexes. These findings emphasise the need to account for non-local conduction in dynamic solar phenomena and highlight the potential of the SNB model for improving the realism of flare simulations. Flux-limited conduction models cannot reproduce the results of non-local transport covered by the SNB model.