Electron Power-Law Spectra in Solar and Space Plasmas

Abstract

Particles are accelerated to very high, non-thermal energies in solar and space plasma environments. While energy spectra of accelerated electrons often exhibit a power law, it remains unclear how electrons are accelerated to high energies and what processes determine the power-law index δ . Here, we review previous observations of the power-law index δ in a variety of different plasma environments with a particular focus on sub-relativistic electrons. It appears that in regions more closely related to magnetic reconnection (such as the 'above-the-looptop' solar hard X-ray source and the plasma sheet in Earth's magnetotail),

Disturbance of the Front Region of Magnetic Reconnection Outflow Jets due to the Lower-Hybrid Drift Instability

“…In a solar flare, since the typical n and B are roughly in the range 10 8 -10 10 cm −3 and 1-100 G (10 5 -10 7 nT), respectively [2], ω pe =ω ce would be of the order of 1-10. Past comparison studies have also discussed these similarities of ω pe =ω ce ð∝ V A Þ and plasma β between the magnetotail and solar flares [27][28][29]. Thus, the LHDI turbulence as seen in the present simulation may frequently occur in the reconnection jet front regions at many locations in space including Earth's magnetotail and solar flares.…”

The study of coherent optical pulsations of the millisecond pulsar PSR J1023+0038 on Russian 6‐m telescope

“…Finally, let us stress the importance of magnetic reconnections for an acceleration of electrons that produce the observed optical emission. It seems that only this mechanism may lead to the formation of ensemble of electrons with such soft energetic spectrum, with the slope close to −8.6 (Oka et al ) (which is necessary for generation of synchrotron spectrum with the slope of β = 3.8).…”

Determining the Dominant Acceleration Mechanism during Relativistic Magnetic Reconnection in Large-scale Systems

“…It has been discussed in solar and space environments (Kopp & Pneuman 1976;Phan et al 2000), laboratory experiments (Ji et al 1998), and recently in the context of highenergy astrophysics (de Gouveia dal Pino & Lazarian 2005;Giannios et al 2009;Arons 2012;Hoshino & Lyubarsky 2012;Zhang & Yan 2011;McKinney & Uzdensky 2012;Zhang et al 2015Zhang et al , 2018. There is strong observational evidence suggesting that reconnection is an efficient process for producing energetic particles in various heliophysics and astrophysical systems (Birn et al 2012;Krucker et al 2010;Øieroset et al 2002;Oka et al 2018;Gary et al 2018;Abdo et al 2011;Tavani et al 2011). However, the acceleration physics remains an area of active research.…”