Magnetic Reconnection - Science topic

The apparent slipping motion of flare loops is regarded as a key feature of the 3D magnetic reconnection in the solar flares. The slippage with a super-Alfvénic speed could be defined as slipping–running reconnection, while the slippage with a sub-Alfvénic speed is called slipping reconnection. Due to the limitation of the observational instrument...

The Analyzers for Cusp Ions (ACIs) on the TRACERS mission measure ion velocity distribution functions in the magnetospheric cusp from two closely spaced spacecraft in low Earth orbit. The precipitating and upflowing ion measurements contribute to the overarching goal of the TRACERS mission and are key to all three science objectives of the mission....

We investigate the three‐dimensional structures of a prominence‐cavity system from two distinct vantage points. For this purpose, we have used the observations recorded by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and the Extreme Ultraviolet Imager (EUVI) on board the Solar Terrestrial Relations Observatory ‐ Ahead (S...

I briefly review the canonical vorticity theoretical framework and its applications in collisionless, magnetized plasma physics. The canonical vorticity is a weighted sum of the fluid vorticity and the magnetic field and is equal to the curl of the canonical momentum. By taking this variable as the primary variable instead of the magnetic field, va...

The looptop region in solar flares is a crucial site to understand the physical processes of magnetic reconnection and particle acceleration. Here, we report novel details of a flare looptop X-ray source that is associated with electron acceleration. The looptop source exhibits an oscillation in height that is statistically anticorrelated with the...

As known, large near-Earth proton enhancements usually occur after major eruptive solar flares accompanied by strong microwave bursts. Typically, the spectral-maximum frequency of such a burst exceeds 10 GHz, and the flux exceeds \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usep...

Explaining fast magnetic reconnection in electrically conducting plasmas has been a theoretical challenge in plasma physics since its first description by Eugene N. Parker. In recent years, the observed reconnection rate has been shown by numerical simulations to be explained by the plasmoid instability that appears in highly conductive plasmas. In...

The Sun's open-closed flux boundary (OCB) separates closed and open magnetic field lines, and is the site for interchange magnetic reconnection processes thought to be linked to the origin of the slow solar wind (SSW). We analyse the global magnetic field structure and OCB from December 2010 to December 2019 using three coronal magnetic field model...

An overview is presented of our current understanding and open questions related to magnetic reconnection in solar flares and the near-sun (within around 20\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\odds...

Extreme space weather events require particle‐in‐cell (PIC) modeling to capture the kinetic physics of magnetic reconnection that is not present in magnetohydrodynamic (MHD) models. The MHD with Adaptively Embedded Particle‐In‐Cell (MHD‐AEPIC) model (Chen et al., 2020, https://doi.org/10.1029/2020ea001331) builds on the operational Michigan Geospac...

We present a one-fluid pair plasma magnetohydrodynamical model for asymmetric relativistic magnetic reconnection that incorporates the thermal-inertial effects of the plasma. We find the general scaling relation for the reconnection rate in a Sweet-Parker-type configuration. However, we show that under a specific highly asymmetric scenario, this ma...

Ion measurements made with the Hot Plasma Composition Analyzers of the Magnetospheric Multiscale Mission (MMS-HPCAs) during the Mother's Day Storm (Gannon Storm) of 10-13 May 2024 yield the first observations of atomic and molecular nitrogen ions in the Earth's dayside outer magnetosphere. A population of ions identified as doubly charged nitrogen...

We present the results of the first multi-event study of the normalized reconnection rate integrating events spanning the three primary regimes of reconnection observed by the Magnetospheric Multiscale (MMS) mission. We utilize a new method for determining the normalized reconnection rate with fewer sources of uncertainty by estimating the diffusio...

Solar supergranulation is a large-scale convective structure on the solar surface, whose formation mechanism and dynamical properties are closely related to key physical processes such as solar magnetic field evolution, coronal heating, and solar wind acceleration. This paper reviews recent research progress on solar supergranulation, focusing on t...

Whistler waves have been observed via many space satellite observations in magnetic reconnection in the Earth′s magnetopause. We study wave–particle interactions between whistler waves and electrons by means of a two-dimensional particle-in-cell simulation of asymmetric reconnection where the guide field strength is 0.3 times the reconnecting magne...

This paper presents the gamma-ray spectral and timing results from the long-term regular observations of Mrk 421 with the Large Area Telescope (LAT) onboard Fermi during 2008 August - 2023 August. We discerned six periods the relatively stronger 0.3-300 GeV activity compared to other time intervals. The baseline brightness level varied on timescale...

This study explores the generation of Electrostatic (ES) Electron Kelvin-Helmholtz instability (EKHI) in collisionless plasma with a step-function electron velocity shear akin to that developed in the electron diffusion region in magnetic reconnection. In incompressible plasma, ES EKHI doesn't arise in any velocity shear profile due to the decoupli...

Magnetic reconnection often initiates abruptly and then rapidly progresses to a nonlinear quasi‐steady state. While satellites frequently detect reconnection events, ascertaining whether the system has achieved steady‐state or is still evolving in time remains challenging. Here, we propose that the relatively rapid opening of the reconnection separ...

This is a poster for the 6th Asian Conference on Science, Technology & Medicine (ACSTM). The conference will be held virtually on February 25-26, 2025. In this poster, consider how it is possible to use the energy released during the reconnection of magnetic fields in a conductive medium, namely plasma, for industrial purposes.

This work presents the first numerical investigation of using Voigt regularization as a method for obtaining magnetohydrodynamic (MHD) equilibria without the assumption of nested magnetic flux surfaces. Voigt regularization modifies the MHD dynamics by introducing additional terms that vanish in the infinite-time limit, allowing for magnetic reconn...

Magnetic reconnection is a ubiquitous process in plasma physics, driving rapid and energetic events such as coronal mass ejections. Reconnection between magnetic fields with arbitrary shear can be decomposed into an anti-parallel reconnecting component and a non-reconnecting guide-field component, which is parallel to the reconnecting electric fiel...

This is a presentation for the 6th Asian Conference on Science, Technology & Medicine (ACSTM). The conference will be held virtually on February 25-26, 2025. In the presentation "Single-Volume Magnetic Reconnection Converter (further MRC) with Variable β of Plasmas" consider how it is possible to use the energy released during the reconnection of m...

Context. During a solar flare, electrons are accelerated to non-thermal energies as a result of magnetic reconnection. These electrons then propagate upwards and downwards from the energy release site along magnetic field lines and produce radio and X-ray emission. Aims. On 11 November 2022, an M5.1 solar flare was observed by the Spectrometer/Tele...

Recent observations of the solar atmosphere in cool extreme ultraviolet (EUV) lines have reported the prevalence of coronal rain falling from coronal cloud filaments that are associated with the magnetic dips of coronal X-point structures. These filaments mysteriously appear as clouds of mass in the corona that subsequently shrink and disappear due...

Electron energization by magnetic reconnection has historically been studied in the Lagrangian guiding-center framework. Insights from such studies include that Fermi acceleration in magnetic islands can accelerate electrons to high energies. An alternative Eulerian fluid formulation of electron energization was recently used to study electron ener...

The apparent slipping motion of flare loops is regarded as a key feature of the 3D magnetic reconnection in the solar flares. The slippage with a super-Alfv\'enic speed could be defined as slipping-running reconnection while the slippage with a sub-Alfv\'enic speed is called slipping reconnection. Due to the limitation of the observational instrume...

During a solar flare, electrons are accelerated to non-thermal energies as a result of magnetic reconnection. These electrons then propagate upwards and downwards from the energy release site along magnetic field lines and produce radio and X-ray emission. On 11 November 2022, an M5.1 solar flare was observed by the Spectrometer/Telescope for Imagi...

Using three‐dimensional particle‐in‐cell (PIC) simulations, we study the spread of magnetic reconnection X‐line. We show that structural asymmetries along the X‐line direction develop during its spread. On the plane of the current sheet (i.e., corresponding to the equatorial plane of the magnetotail), sharp cusp‐shaped signatures develop along the...

This paper presents the gamma-ray spectral and timing results from the long-term regular observations of Mrk 421 with the Large Area Telescope (LAT) onboard Fermi during 2008 August–2023 August. We discerned six periods of the relatively stronger 0.3–300 GeV activity compared to other time intervals. The baseline brightness level varied on timescal...

Influences of the out-of-plane streaming flows on the nonlinear evolution of double tearing mode in resistive magnetohydrodynamics have been studied. The results show that the streaming flow has an enhancing effect on the double tearing instabilities. It is found that the streaming flow facilitates the merging process of upper (lower) magnetic isla...

Toroidal magnetic field is a key ingredient of relativistic jets launched by certain accreting astrophysical black holes, and of plasmoids emerging from the tearing instability during magnetic reconnection, a candidate dissipation mechanism in jets. Tension of toroidal field is an anisotropic force that can compress local energy and momentum densit...

Context. Outflows perpendicular to the guide field are believed to be a possible signature of magnetic reconnection in the solar corona. Specifically, outflows can help detect the occurrence of ubiquitous small-angle magnetic reconnection. Aims. The aim of this work is to identify possible diagnostic techniques of such outflows in hot coronal loops...

At the Earth's dayside magnetopause, a cold ion population of ionospheric or plasmasphere origin is commonly observed at the magnetospheric side. In this study we use a 2.5D Particle‐in‐Cell simulation to investigate the energization of cold ions in the separatrix near X‐line and the escape process. And we identify observation events made by the Ma...

Magnetic reconnection converts magnetic field energy into particle energy by breaking and reconnecting magnetic field lines. Magnetic reconnection is a kinetic process that generates a wide variety of kinetic waves via wave-particle interactions. Kinetic waves have been proposed to play an important role in magnetic reconnection in collisionless pl...

We present the 2D gyrofluid magnetic reconnection code GREENY (Gyrofluid Reconnection with Extended Electromagnetic Nonlinearity). After a brief introduction to gyrofluids, magnetic reconnection, and the implemented models, we discuss the numerical framework and the algorithmic treatment of the quasi-neutrality condition and Amper\`e's law. Next, w...

An instability criterion in the magnetohydrodynamics (MHD) with the open boundary of a magnetic field is proposed in this paper. We use a series of linear force-free extrapolation fields, in which the normal part of the magnetic field is fixed, to obtain the linear fitting coefficient called relative alpha by using the cojoined value of magnetic fr...

The Analyzer for Cusp Electrons (ACE) instruments on the Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) mission provide measurements of electron velocity distribution functions from two closely spaced spacecraft in a low Earth orbit that passes through the magnetospheric cusp. The precipitating and upward-going ele...

Magnetic reconnection during a sawtooth crash in a tokamak can be characterized by the radial velocity of the hot core. This paper presents a comparative study of reconnection rates observed in ASDEX Upgrade and EAST tokamaks. The findings demonstrate qualitative agreement with theoretical predictions, indicating that two-fluid effects, such as par...

In this paper, we present a magnetohydrodynamics simulation of NOAA active region 11166 to understand the origin of a confined X-class flare that peaked at 23:23 UT on 2011 March 9. The simulation is initiated with a magnetic field extrapolated from the corresponding photospheric magnetogram, using a non-force-free-field extrapolation technique. Im...

We present consecutive observations of Flux Transfer Events (FTEs) on 10 November 2020, using MMS, THEMIS and Cluster spacecraft located at different magnetopause locations. Two typical scale FTE signatures are successively observed by low‐latitude THEMIS, mid‐latitude MMS and high latitude Cluster, reflecting their global spatial scale characteris...

An International Space Science Institute (ISSI) workshop was convened to assess recent rapid advances in studies of magnetic reconnection made possible by the NASA Magnetospheric Multiscale (MMS) mission and to place them in context with concurrent advances in solar physics by the Parker Solar Probe, astrophysics, planetary science and laboratory p...

We investigate the evolution of particle acceleration, loops heated by the energy release, and the trajectories of flare-accelerated electrons observed up to one solar radius above the active region in a B-class flare on 6 June 2020. We studied the downward particle acceleration and thermal evolution with observations by the Spectrometer/Telescope...

The flapping motion of the current sheet is a common dynamic phenomenon in the planetary magnetosphere and plays an important role in the transportation of energy and disturbances. Based on the measurements from the Cassini spacecraft, we investigate the short‐period flapping motions of the current sheet characterized by periods significantly much...

This short article highlights unsolved problems of magnetic reconnection in collisionless plasma. Advanced in-situ plasma measurements and simulations have enabled scientists to gain a novel understanding of magnetic reconnection. Nevertheless, outstanding questions remain concerning the complex dynamics and structures in the diffusion region, cros...

The triggering mechanism of the substorm onset has been a major issue in magnetospheric research. Various models have been proposed so far. To understand the causal relationship of magnetotail processes associated with substorm onsets, our previous studies performed a series of statistical analyses of Geotail and Time History of Events and Macrosca...

Magnetic reconnection is a ubiquitous plasma process that transforms magnetic energy into particle energy during eruptive events throughout the universe. Reconnection not only converts energy during solar flares and geomagnetic substorms that drive space weather near Earth, but it may also play critical roles in the high energy emissions from the m...

During geomagnetic storms, cold ions from the ionosphere substantially contribute to the plasma sheet population, which may significantly impact magnetotail energy conversion and transport. However, the energization of cold ions in the magnetotail during storm periods remains poorly understood. This paper investigates cold ion energization by secon...

We performed 2D PIC simulations of Kelvin–Helmholtz instability (KHI) with symmetric and asymmetric density and temperature profiles along the flow shear with primarily a northward interplanetary magnetic field with a small uniform in-plane field. The aim of this study is to understand the role and degree of magnetic reconnection in the evolution o...

EUV brightenings are small-scale magnetic reconnection events that consistently appear before and after solar flares. However, it is not well understood how EUV precursors might foreshadow flares and what the physical connection is between the EUV signatures and flares. We studied flare-active and inactive periods in three separate studies using th...

We detail the emission behaviors of three long-period pulsars detected using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) during the CRAFTS survey. Their rotational periods range from 1.83 s to 4.75 s, and the null fractions measure between 28% and 53%. PSR J1945+1211 and PSR J2323+1214 exhibited quasi-periodic nulls, with durat...

Electron current layers, which form in various natural and laboratory plasmas, are susceptible to multiple instabilities, with tearing being a prominent instability driven by current gradients. Tearing is considered a potential mechanism for magnetic reconnection in collisionless regimes, where electron inertia acts as a non-ideal factor that cause...

Context. It is accepted that magnetic flux ropes might exhibit large-angle rotation in magnetic configurations, including strong external toroidal magnetic fields. The specific mechanisms leading to rotation still remain elusive, however. Aims. We examine the mechanisms by which the external toroidal magnetic field facilitates the flux-rope rotatio...

Cold ions of ionospheric origin have been observed in the Earth's magnetosphere, and it has been argued that these cold ions have greatly influenced the magnetospheric dynamics. In addition to cold ions, cold electrons are also observed in the aforesaid environment. Moreover, double layers have been detected by various spacecraft missions in the te...

The propagation characteristics of nonlinear electron-acoustic (EA) waves are studied in a four-component magneto-plasma, containing inertial cold electrons, warm drifting beam electrons, trapped superthermal hot electrons, and static ions. A linear dispersion relation for EA waves is derived to analyze the impact of electron superthermality on the...

The dynamic structures of solar filaments prior to solar flares provide important physical clues about the onset of solar eruptions. Observations of those structures under subarcsecond resolution with high cadence are rare. We present high-resolution observations covering preeruptive and eruptive phases of two C-class solar flares, C5.1 (SOL2022-11...

Magnetic reconnection is one of the fundamental dynamical processes in the solar corona. The method of studying reconnection in active region-scale magnetic fields generally depends on non-local methods (i.e. requiring information across the magnetic field under study) of magnetic topology, such as separatrix skeletons and quasi-separatrix layers....

The design and analysis of high energy density (HED) laser experiments typically rely on radiation hydrodynamics simulations. However, some laser–plasma interaction regimes are not collisional and cannot be adequately modeled with hydrodynamics. For example, strongly driven magnetic reconnection and magnetized collisionless shock experiments posses...

The rapid development of an emerging computing device, the graphical processing unit (GPU), has significantly enhanced our ability to conduct full kinetic particle-in-cell (PIC) simulations in space physics. In this paper, we propose an approach that leverages multiple GPUs to facilitate large-scale PIC simulations. This method can effectively redu...

Plasma circulation and magnetic reconnection are crucial for understanding the dynamics of Jupiter's magnetosphere. Previous studies identified hundreds of reconnection sites at distances of 50–100 RJ ${\mathrm{R}}_{J}$ from magnetic field signatures. Recent analysis of thermal plasma data from the Juno/JADE instrument shows super‐corotating flows...

Black hole X-ray binaries (BHXBs) are observed in various wavelengths from radio to GeV gamma-ray. Several BHXBs, including MAXI J1820+070 and Cygnus X-1, are also found to emit ultrahigh-energy (UHE; photon energy $>$100 TeV) gamma rays. The origin and production mechanism of the multi-wavelength emission of BHXBs are under debate. We propose a sc...

During relativistic magnetic reconnection, antiparallel magnetic fields undergo a rapid change in topology, releasing a large amount of energy in the form of non-thermal particle acceleration. This work explores the application of mesh refinement to 2D reconnection simulations to efficiently model the inherent disparity in length-scales. We have sy...

The global effects on Venusian magnetic topology and ion escape during the significant solar-wind disturbances caused by the interplanetary coronal mass ejection (ICME) remain an open area of research. This study examined a particularly intense ICME interaction with Venus on November 5, 2011, using a global multifluid magnetohydrodynamics (MHD) mod...

Earth's magnetotail, a night‐side region characterized by stretched magnetic field lines and strong plasma currents, is the primary site for the release of magnetic field energy and its transformation into plasma heating and kinetic energy plus charged particle acceleration during magnetic reconnection. In this study, we demonstrate that the effici...

Field-particle energy exchange is important to the magnetic reconnection process, but uncertainties regarding the time evolution of this exchange remain. We investigate the temporal dynamics of field-particle energy exchange during magnetic reconnection, using Magnetospheric Multiscale mission observations of an electron-only reconnection event in...

The origin of large-amplitude magnetic field deflections in the solar wind, known as magnetic switchbacks, is still under debate. These structures, which are ubiquitous in the observations made by Parker Solar Probe, likely have their seed in the lower solar corona, where small-scale events driven by magnetic reconnection could provide conditions r...

The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic center, has long been examined in the radio-to-millimeter, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) r...

In this paper, we present a magnetohydrodynamics simulation of NOAA active region 11166 to understand the origin of a confined X-class flare that peaked at 23:23 UT on 2011 March 9. The simulation is initiated with a magnetic field extrapolated from the corresponding photospheric magnetogram using a non-force-free-field extrapolation technique. Imp...

Recently, magnetic reconnection has attracted considerable attention as a novel energy extraction mechanism, relying on the rapid reconnection of magnetic field lines within the ergosphere. We have investigated the properties of the energy extraction via magnetic reconnection in a Konoplya–Zhidenko rotating non-Kerr black hole spacetime with an ext...

Context. The origin of large-amplitude magnetic field deflections in the solar wind, known as magnetic switchbacks, is still under debate. These structures, which are ubiquitous in the in situ observations made by Parker Solar Probe (PSP), likely have their seed in the lower solar corona, where small-scale energetic events driven by magnetic reconn...

The physical origin of active galactic nucleus (AGN) variability remains unclear. Here we propose that the magnetic reconnection driven by the migration of satellite black holes (sBHs) in the AGN disc can be a new plausible mechanism for AGN short-term variability. During the sBH migration, the co-moving plasmas surrounding the sBH could influence...

The present study performs a procedure of estimating the current sheet (CS) thickness in the solar wind. Motivated by the science requirements for a multi‐spacecraft solar wind mission called the Seven Sisters, this research aims to address the required temporal resolution of the magnetometer in order to entirely encompass the observations of thin...

Relativistic magnetic turbulence has been proposed as a process for producing nonthermal particles in high-energy astrophysics. The particle energization may be contributed by both magnetic reconnection and turbulent fluctuations, but their interplay is poorly understood. It has been suggested that during magnetic reconnection the parallel electric...

Context. The elongated bright structures above solar flare loops are suggested to be current sheets, where magnetic reconnection takes place. Observations have revealed various characteristics of the current sheet; however, their physical origin remains to be ascertained. Aims. In this study we aim to reveal the relations of observational character...

Global 3-D magnetohydrodynamical simulations have been conducted to study magnetospheric accretion around stars with various spin rates. For slow rotators, characterized by a fastness parameter $\omega_s\lesssim 0.78$, the disk's inner edge at the magnetospheric truncation radius becomes unstable to the interchange instability, leading to intruding...

Weak-line T Tauri stars (WTTS) exhibit X-ray flares, likely resulting from magnetic reconnection that heats the stellar plasma to very high temperatures. These flares are difficult to identify through targeted observations. Here, we report the serendipitous detection of the brightest X-ray flaring state of the WTTS KM Ori in the eROSITA DR1 survey....

The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic Center, has long been examined in the radio-to-mm, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) regime. T...

High-energy particles may be accelerated widely in stellar coronae; probably by the same processes we find in the Sun. Here, we have learned of two physical mechanisms that dominate the acceleration of solar energetic particles (SEPs). The highest energies and intensities are produced in "gradual" events at shock waves driven from the Sun by fast,...

Plain Language Summary Magnetic reconnection is a fundamental process in plasmas during which magnetic field energy is transferred, often explosively, to plasma particles. Magnetic reconnection develops in current sheets—extended regions of enhanced electric currents that are ubiquitous in plasmas. Current sheets are also the natural seedbed of pla...

Plain Language Summary Magnetic reconnection can release magnetic energy and energize particles. Hence, reconnection is thought to be responsible for many explosive phenomena in space. Flux ropes are generated by reconnection and can affect the reconnection processes in turn. Flux ropes are important places for electron acceleration and energy conv...

Magnetic reconnection leads to the formation of island-shaped magnetic structure(s). Due to disagreement between theoretical evaluations of the characteristic reconnection time and observations, it is commonly accepted that the collisionality (or resistivity) is too low to explain magnetic reconnection phenomena in fusion plasmas. Thus, magnetic re...