Spatially inhomogeneous acceleration of electrons in solar flares

Abstract

The imaging spectroscopy capabilities of the Reuven Ramaty high energy solar spectroscopic imager (RHESSI) enable the examination of the accelerated electron distribution throughout a solar flare region. In particular, it has been revealed that the energisation of these particles takes place over a region of finite size, sometimes resolved by RHESSI observations. In this paper, we present, for the first time, a spatially distributed acceleration model and investigate the role of inhomogeneous acceleration on the observed X-ray emission properties. We have modelled transport explicitly examining scatter-free and diffusive transport within the acceleration region and compare with the analytic leaky-box solution. The results show the importance of including this spatial variation when modelling electron acceleration in solar flares. The presence of an inhomogeneous, extended acceleration region produces a spectral index that is, in most cases, different from the simple leaky-box prediction. In particular, it results in a generally softer spectral index than predicted by the leaky-box solution, for both scatter-free and diffusive transport, and thus should be taken into account when modelling stochastic acceleration in solar flares.

10 pages, submitted to Astronomy and Astrophysics Journal

References in corpus (6)

• Relations between concurrent hard X-ray sources in solar flares
• The Formation of Kappa-Distribution Accelerated Electron Populations in Solar Flares
• Stereoscopic electron spectroscopy of solar hard X-ray flares with a single spacecraft
• On the variation of solar flare coronal x-ray source sizes with energy
• Numerical consideration of quasilinear electron cloud dynamics in plasma
• Measurements of electron anisotropy in solar flares using albedo with RHESSI X-ray data

Cited by in corpus (6)

• The Spatial and Temporal Variations of Turbulence in a Solar Flare
• A count-based imaging model for the Spectrometer/Telescope for Imaging X-rays (STIX) in Solar Orbiter
• Accelerated particle beams in a 3D simulation of the quiet Sun
• Spectral and Imaging Diagnostics of Spatially-Extended Turbulent Electron Acceleration and Transport in Solar Flares
• Flare-accelerated Electrons in the Kappa Distribution from X-Ray Spectra with the Warm-Target Model
• Time-dependent Turbulent Electron Acceleration and Transport in Solar Flares