Energy Partition of Thermal and Nonthermal Particles in Magnetic Reconnection

Hoshino, Masahiro

doi:10.3847/1538-4357/acbfb5

Cited by 6 publications

(2 citation statements)

References 54 publications

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“…We term this lower-energy bound as the injection energy γ inj , above which particles are accelerated into the nonthermal energies. This transition energy is also important for understanding the partition between thermal and nonthermal distribution (Hoshino 2023;French et al 2023). As the guide field becomes stronger, the energy spectra are softer, and the high-energy cutoff is suppressed (French et al 2023).…”

Section: Nonthermal Acceleration Uncovered By Pic Simulationsmentioning

confidence: 99%

“…Recently, the energy partitioning has been quantitatively investigated by using PIC simulations for a pair plasma (Hoshino 2022(Hoshino , 2023. The downstream heated plasma by reconnection has been found to be well modeled by a composed distribution function consisting of a Maxwell distribution function N M (γ ) and a kappa distribution function N κ (γ ), where (γ ), where f cut (γ ) represents the high energy cutoff function given by exp(−(γ − γ cut )/γ cut ) for γ > γ cut .…”

Section: Energy Partition Of Thermal and Nonthermal Particles In Reco...mentioning

confidence: 99%

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Magnetic Reconnection and Associated Particle Acceleration in High-Energy Astrophysics

Guo,

Liu,

Zenitani

et al. 2024

Space Sci Rev

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Magnetic reconnection occurs ubiquitously in the universe and is often invoked to explain fast energy release and particle acceleration in high-energy astrophysics. The study of relativistic magnetic reconnection in the magnetically dominated regime has surged over the past two decades, revealing the physics of fast magnetic reconnection and nonthermal particle acceleration. Here we review these recent progresses, including the magnetohydrodynamic and collisionless reconnection dynamics as well as particle energization. The insights in astrophysical reconnection strongly connect to the development of magnetic reconnection in other areas, and further communication is greatly desired. We also provide a summary and discussion of key physics processes and frontier problems, toward a better understanding of the roles of magnetic reconnection in high-energy astrophysics.

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Section: Nonthermal Acceleration Uncovered By Pic Simulationsmentioning

confidence: 99%

Section: Energy Partition Of Thermal and Nonthermal Particles In Reco...mentioning

confidence: 99%

Magnetic Reconnection and Associated Particle Acceleration in High-Energy Astrophysics

Guo,

Liu,

Zenitani

et al. 2024

Space Sci Rev

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Exploring self-consistent 2.5D flare simulations with MPI-AMRVAC

Druett,

Ruan,

Keppens

2024

A&A

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Multidimensional solar flare simulations have not yet included a detailed analysis of the lower atmospheric responses, such as downflowing chromospheric compressions and chromospheric evaporation processes. We present an analysis of multidimensional flare simulations, including an analysis of chromospheric upflows and downflows that provides important groundwork for comparing 1D and multidimensional models We followed the evolution of a magnetohydrodynamic standard solar flare model that includes electron beams and in which localized anomalous resistivity initiates magnetic reconnection. We varied the background magnetic field strength to produce simulations that cover a large span of observationally reported solar flare strengths. Chromospheric energy fluxes and energy density maps were used to analyze the transport of energy from the corona to the lower atmosphere, and the resultant evolution of the flare. Quantities traced along 1D field lines allowed for detailed comparisons with 1D evaporation models. The flares produced by varying the background coronal field strength between 20 G and 65 G have GOES classifications between B1.5 and M2.3. All produce a lobster claw reconnection outflow and a fast shock in the tail of this flow with a similar maximum Alfv\'en Mach number of sim 10. The impact of the reconnection outflow on the lower atmosphere and the heat conduction are the key agents driving the chromospheric evaporation and "downflowing chromospheric compressions." The peak electron beam heating flux in the lower atmospheres varies between $1.4 $ and $4.7 $ erg cm$^ $ s$^ $ across the simulations. The downflowing chromospheric compressions have kinetic energy signatures that reach the photosphere, but at subsonic speeds they would not generate sunquakes. The weakest flare generates a relatively dense flare loop system, despite having a negative net mass flux, through the top of the chromosphere, that is to say, more mass is supplied downward than is evaporated upward. The stronger flares all produce positive mass fluxes. Plasmoids form in the current sheets of the stronger flares due to tearing, and in all experiments the loop tops contain turbulent eddies that ring via a magnetic tuning fork process. The presented flares have chromospheric evaporation driven by thermal conduction and the impact and rebound of the reconnection outflow, in contrast to most 1D models where this process is driven by the beam electrons. Several multidimensional phenomena are critical in determining plasma behavior but are not generally considered in 1D flare simulations. They include loop-top turbulence, reconnection outflow jets, heat diffusion, compressive heating from the multidimensional expansion of the flux tubes due to changing pressures, and the interactions of upward and downward flows from the evaporation meeting the material squeezed downward from the loop tops.

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A hard energy spectrum in 3D guide-field magnetic reconnection

Hoshino

2024

Physics of Plasmas

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Magnetic reconnection has long been known to be the most important mechanism not only for mixing the plasmas by changing the magnetic field topology but also for releasing the magnetic field energy into the plasma kinetic energy. During magnetic energy release, it is possible for some of the heated plasma to be accelerated to energies much higher than the thermal energy. Recently, the energy partitioning of the thermal and the nonthermal energy has been studied by using particle-in-cell (PIC) simulations, and it has been shown that the acceleration efficiency of nonthermal particles increases with increase in the plasma temperature, and the nonthermal energy density occupies more than 90% in the total heated plasma when the Alfvén velocity is close to the speed of light, c. However, the acceleration efficiency decreases as the guide magnetic field increases. So far, the acceleration efficiency has been mainly studied in two-dimensional systems, but it is interesting to study three-dimensional effects where the patchy and turbulent reconnection can dynamically occur. This study explores the effects of three-dimensional relativistic reconnection on a pair plasma with the guide magnetic field, utilizing three-dimensional (3D) PIC simulations. The results indicate that the decrease in nonthermal particle production is smaller in 3D guide-field reconnection compared to 2D. More importantly, contrary to general expectation, 3D reconnection is capable of maintaining a hard nonthermal energy spectrum even in the presence of a strong guide magnetic field.

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Energy Partition of Thermal and Nonthermal Particles in Magnetic Reconnection

Cited by 6 publications

References 54 publications

Magnetic Reconnection and Associated Particle Acceleration in High-Energy Astrophysics

Magnetic Reconnection and Associated Particle Acceleration in High-Energy Astrophysics

Exploring self-consistent 2.5D flare simulations with MPI-AMRVAC

A hard energy spectrum in 3D guide-field magnetic reconnection

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