Temporal Intermittency of Energy Dissipation in Magnetohydrodynamic Turbulence

TL;DR

This paper investigates the temporal intermittency of energy dissipation in MHD turbulence through numerical simulations, revealing power-law distributions of flare events and their significance in space and astrophysical phenomena.

Contribution

It introduces a detailed analysis of four-dimensional spatiotemporal structures of energy dissipation, highlighting their complex nature and scaling relations in MHD turbulence.

Findings

Power-law distribution of dissipated energy with index ~ -1.75

Temporal asymmetry of flare events as cascade signature

Robust scaling relations in complex flare structures

Abstract

Energy dissipation in magnetohydrodynamic (MHD) turbulence is known to be highly intermittent in space, being concentrated in sheet-like coherent structures. Much less is known about intermittency in time, another fundamental aspect of turbulence which has great importance for observations of solar flares and other space/astrophysical phenomena. In this Letter, we investigate the temporal intermittency of energy dissipation in numerical simulations of MHD turbulence. We consider four-dimensional spatiotemporal structures, "flare events", responsible for a large fraction of the energy dissipation. We find that although the flare events are often highly complex, they exhibit robust power-law distributions and scaling relations. We find that the probability distribution of dissipated energy has a power law index close to -1.75, similar to observations of solar flares, indicating that intense dissipative events dominate the heating of the system. We also discuss the temporal asymmetry of flare events as a signature of the turbulent cascade.