Current Sheet Research Articles

Multi-wavelength pulse profiles from the force-free neutron star magnetosphere

Context. The last two decades have witnessed dramatic progress in our understanding of neutron star magnetospheres thanks to force-free and particle-in-cell simulations. However, the associated particle dynamics and its emission mechanisms and locations have not been fully constrained, notably in X-rays. Aims. In this paper, we compute a full atlas of radio, X-ray, and γ-ray pulse profiles, relying on the force-free magnetosphere model. Our goal is to use such a data bank of multi-wavelength profiles to fit a substantial number of radio-loud γ-ray pulsars that have also been detected in non-thermal X-rays to decipher the X-ray radiation mechanism and sites. Using results from the third γ-ray pulsar catalogue (3PC), we investigate the statistical properties of this population. Methods. We assume that radio emission emanates from field lines rooted to the polar caps, at varying height above the surface, close to the surface, at an altitude about 5–10% of the light cylinder radius, r L. The X-ray photons are produced in the separatrix region within the magnetosphere; that is, the current sheet formed by the jump from closed to open magnetic field lines. We allow for substantial variations in emission height. The γ-rays are produced within the current sheet of the striped wind, outside the light cylinder. Results. A comprehensive set of radio, X-ray, and γ-ray light curves was computed. Based on only geometric considerations about magnetic obliquity, line-of-sight inclination, and the radio beam cone opening angle, pulsars can be classified as radio-loud or quiet and as γ-ray-loud or quiet. We found that the 3PC sample is compatible with an isotropic distribution of obliquity and line of sight. Conclusions. The atlases constructed in this work are the fundamental tools with which to explore individual pulsars and fit their multi-wavelength pulse profiles in order to constrain their magnetic topology, the emission sites, and the observer’s line of sight.

Extreme-ultraviolet (EUV) observables of simulated plasmoid-mediated reconnection in the solar corona

Context. Understanding the role of magnetic reconnection in the heating and dynamics of the solar atmosphere requires detailed observational data of any observable aspect of the reconnection process, including small-scale features such as plasmoids. Aims. Here, we examine the capability of active and upcoming instruments to detect plasmoids generated by reconnection in the corona including low-density regimes. Methods. We used the Bifrost code to perform simulations of plasmoid-mediated reconnection in the corona with a 2D idealized setup: a fan-spine topology with uniform density including thermal conduction. Through a forward-modeling of extreme-ultraviolet (EUV) observables, we checked whether our simulated plasmoids could be detected with the instruments of Solar Dynamics Observatory (SDO) and Solar Orbiter (SO), as well as the upcoming Multi-Slit Solar Explorer (MUSE) and Solar-C missions. Results. Short-lived (∼10 − 20 s) small-scale (∼0.2 − 0.5 Mm) coronal plasmoids are not resolvable with the Atmospheric Imaging Assembly (AIA) on board SDO. In contrast, they could be captured with the EUV High-Resolution Imager at the Extreme Ultraviolet Imager (EUI-HRIEUV) of SO. The spatial and temporal high-resolution planned for the MUSE spectrograph (SG) is adequate to obtain full spectral information of these plasmoids. To achieve a sufficient signal-to-noise ratio (S/N) for ∼0.8 MK plasmoids in the MUSE/SG 171 Å channel, full-raster images are attainable for regions with electron densities above 109 cm−3, while sit-and-stare observations are recommended for lower-density regions. The future Solar-C mission could also capture these coronal plasmoids using the EUV High-Throughput Spectroscopic Telescope (EUVST), considering rapid changes in Doppler shift and line widths in different EUV lines caused by plasmoid motions along the current sheet. Conclusions. With the combined spectra of MUSE/SG and Solar-C/EUVST in multiple emission lines, along with high-resolution images from SO/EUI-HRIEUV and MUSE/CI, it should be possible to gain new insights about plasmoid formation in the corona.

Dynamical Evolution of Newly Formed Structures After Magnetic Reconnection

Although extensive research on magnetic reconnection, e.g., current sheets, inflows/outflows, and plasma ejections, has been done, the dynamical evolution of newly formed structures during and after the reconnection between two sets of atmospheric structures is rarely studied. Here we investigate five reconnection events based on observations from the Solar Dynamics Observatory and the New Vacuum Solar Telescope. In each event, two independent atmospheric structures are involved. While they meet, a plasma sheet is detected. After exchanging topological connectivity, new structures are formed in the outflow regions. For each new structure, it is composed of a part of one original structure and that of the other one. In this Letter, for the first time, we find that there are two types of evolution patterns of the new structures. The first type is that the new structures move away from the reconnection position as a whole and then undergo a to-and-fro motion (an oscillation). The second is that the new structures display a “throwing whip” movement. We suggest that the evolution patterns are relevant to the topological configuration of the original structures and the position of the reconnection site.

The Colocation of Magnetic Reconnection and Current Disruption in Jovian Middle Magnetosphere

Magnetic reconnection and current disruption are two key processes in driving energy conversion and dissipation in planetary magnetospheres. At the Earth, the two processes usually occur at different locations: the current disruption process occurs more frequently in the near-Earth magnetotail ∼10 R E, while the magnetotail reconnection process is expected to take place in the more distant region where the current sheet is thinner. Occasionally, under very intense solar wind perturbations, reconnection could be located closer to the Earth where current disruption processes usually operate. But it is unclear what the situation is at giant planets, in which the plasma environment is very different from the Earth. In this study, we investigate a middle-Jupiter reconnection event at ∼43 R J. During the event, the inferred integrated cross-field currents were substantially reduced, which we argue is a signature of current disruption. In this case, we suggest that magnetic reconnection could be colocated with a current disruption process in the Jovian magnetosphere, which is roughly analogous to the situation in the extremely perturbed Earth’s magnetosphere.

Isochronous bifurcations of magnetic islands in tokamaks

On a rational magnetic surface, an isochronous bifurcation transforms one island chain into another chain with the same winding number. This transformation has been the subject of recent studies in tokamak plasmas. Namely, visco-resistive magnetohydrodynamic simulations of NSTX-U and DIII-D plasmas showed the onset of bifurcations with new magnetic isochronous islands for two competing helical perturbations on the same rational magnetic surface. To investigate these bifurcations, we use a cylindrical plasma model, with first-order correction for toroidicity, subject to externally applied magnetic perturbations, generated by a pair of resonant helical windings (RHWs) on the external wall and superposed to a helical current sheet (HCS) located on a rational plasma surface. We numerically integrate the magnetic field line equation and show that isochronous islands emerge when the perturbation created by the HCS increases. We present examples of such bifurcations on primary and secondary magnetic surfaces for different RHW configurations.

Compositional Metrics of Fast and Slow Alfvénic Solar Wind Emerging from Coronal Holes and Their Boundaries

We seek to understand the composition and variability of fast solar wind (FSW) and slow Alfvénic solar wind emerging from coronal holes (CHs). We leverage an opportune conjunction between Solar Orbiter and Parker Solar Probe (PSP) during PSP Encounter 11 to include compositional diagnostics from the Solar Orbiter Heavy Ion Sensor as these variations provide crucial insights into the origin and nature of the solar wind. We use potential field source surface and magnetohydrodynamic models to connect the observed plasma at PSP and Solar Orbiter to its origin footpoint in the photosphere and compare these results with the in situ measurements. A very clear signature of a heliospheric current sheet crossing as evidenced by enhancements in low first ionization potential (FIP) elements, ion charge state ratios, proton density, low Alfvénicity, and polarity estimates validates the combination of modeling, data, and mapping. We identify two FSW streams emerging from small equatorial CHs with low ion charge state ratios, low FIP bias, high Alfvénicity, and low footpoint brightness, yet anomalously low alpha particle abundance for both streams. We identify high-Alfvénicity slow solar wind emerging from the overexpanded boundary of a CH having intermediate alpha abundance, high Alfvénicity, and dips in ion charge state ratios corresponding to CH boundaries. Through this comprehensive analysis, we highlight the power of multi-instrument conjunction studies in assessing the sources of the solar wind.

Multiple Flux Rope Dynamics: MMS Observations and Reconstruction Results

A series of six ion-scale magnetic flux ropes (FR1–6) and a thin current sheet, encountered by Magnetospheric Multiscale spacecraft in the magnetosheath side of the dayside magnetopause boundary layer, are studied for multiple flux rope dynamics in terms of energy conversion and two-dimensional geometry structure. The thin current sheet is identified in between FR1 and FR2. The energy exchange between electromagnetic fields and plasmas is dynamic in FR1–5 and also surrounding the flux ropes, while a low-energy conversion rate is seen in FR6. Different energy conversions exist in the flux ropes: energy dynamo is predominant in FR1 and FR5, while energy dissipation is dominated in FR2–4. Both the energy dynamo and dissipation primarily result from j ∥ E ∥. Strong dissipation, surrounded by an energy dynamo, happens at the thin current sheet and is accompanied by ion agyrotropic behavior. From the reconstructed magnetic field maps, the estimated aspect ratios of the six flux ropes are 0.78, 0.16, 0.66, 0.11, 0.40, and 0.46 in order, and the thickness of the thin current sheet is ∼63 km (∼1.8 ion inertial length). Evidently, the magnetic field map shows that FR4 is a coalescing flux rope where a pronounced dissipation is present. The overall finding agrees with the previous simulation studies of multiple island coalescence.

Oblique Compressible Waves in the Reconnection Exhaust Region Embedded in the Inner Heliospheric Current Sheet Observed by Parker Solar Probe

Magnetic reconnection is an important physical process of energy conversion in the heliosphere. Parker Solar Probe (PSP) passes through current sheets of the inner heliosphere and is likely to encounter magnetic reconnection events there. PSP traversed a magnetic reconnection exhaust region that occurred in the coronal streamer during its perihelion Encounter 8. We report an observation of the counterstream of strahl electrons and compressible waves in the exhaust region on the antisunward side of the reconnection site. We analyze the wave characteristics using electromagnetic singular value decomposition techniques and find that the propagation direction of the compressible waves is quasi-perpendicular to the local magnetic field. Combining with the topology of the magnetic field, we infer that the compressible waves converge from the edge to the center of the exhaust region, and then propagate away from it. Further, we select 12 magnetic reconnection events during Encounter 5–8 for statistics and find that the oblique compressible waves are commonly detected throughout the inner heliospheric current sheet. In addition, we discuss the possible nature of wave branches for these compressible waves. Our work shows that magnetic reconnection in the heliosphere not only changes the topology of the large-scale magnetic field in the heliosphere, but also affects the transport characteristics of solar wind plasma and suprathermal particles, and regulates the states of waves and turbulence in the heliosphere.

The unexpected role of heliospheric boundaries in facilitating interstellar dust penetration at 1–5 AU

Aims. Interstellar dust (ISD) particles penetrate the heliosphere because of the relative motion of the local interstellar cloud and the Sun. The penetrated particles pass through the heliospheric interface, that is, the region in which solar wind and interstellar plasma interact. As a result, the ISD flow is modified after the passage through this region under the influence of electromagnetic force. The main goal of this work is to show how the heliospheric interface affects the distribution of ISD particles near the Sun. Methods. We have developed a Monte Carlo model of the ISD distribution in the heliosphere. It first takes the effects of the heliospheric interface and the rotating heliospheric current sheet into account. The effects of the heliospheric interface were probed using a global heliospheric model. Results. The computation results show that the heliospheric interface strongly influences the distribution of relatively small (radius a = 150 − 250 nm) astronomical silicates. The unexpected finding is that the heliospheric interface facilitates the penetration of a = 150 nm particles at small heliocentric distances and, particularly, to the Ulysses orbit (1 − 5 AU). We demonstrate that the deflection of ISD particles in the outer heliosheath is the principal mechanism that causes the effects of the heliospheric interface on the distribution near the Sun. The computations with different heliospheric models show that the distribution near the Sun is sensitive to the plasma parameters in the pristine local interstellar medium. Thus, we demonstrated that being measured near the Sun, the ISD may serve as a new independent diagnostics of the local interstellar medium and the heliospheric boundaries.

Impact of far-side structures observed by Solar Orbiter on coronal and heliospheric wind simulations

Context. Solar Orbiter is a new space observatory that provides unique capabilities to understand the heliosphere. In particular, it has made several observations of the far-side of the Sun and therefore provides unique information that can greatly improve space weather monitoring. Aims. In this study, we aim to quantify how the far-side data will affect simulations of the corona and the interplanetary medium, especially in the context of space weather forecasting. Methods. To do so, we focused on a time period with a single sunspot emerging on the far-side in February 2021. We used two different input magnetic maps for our models: one that includes the far-side active region and one that does not. We used three different coronal models typical of space weather modeling: a semi-empirical model (potential field source surface or PFSS) and two different magnetohydrodynamic models (Wind Predict and Wind Predict-AW). We compared all the models with both remote sensing and in situ observations in order to quantify the impact of the far-side active region on each solution. Results. We find that the inclusion of the far-side active region in the various models has a small local impact due to the limited amount of flux of the sunspot (at most 8% of the total map flux), which leads, for example, to coronal hole changes of around 7% for all models. Interestingly, there is a more global impact on the magnetic structure seen in the current sheet, with clear changes, for example, in the coronal hole boundaries visible in extreme ultra-violet (EUV) on the western limb, which is opposite to the active region and the limb most likely to be connected to Earth. For the Wind Predict-AW model, we demonstrate that the inclusion of the far-side data improves both the structure of the streamers and the connectivity to the spacecraft. Conclusions. In conclusion, the inclusion of a single far-side active region may have a small local effect with respect to the total magnetic flux, but it has global effects on the magnetic structure, and thus it must be taken into account to accurately describe the Sun-Earth connection. The flattening of the heliospheric current sheet for all models reveals that it causes an increase of the source surface height, which in return affects the open and closed magnetic field line distributions.

Direct Observation of Magnetic Reconnection Resulting From Interaction Between Magnetic Flux Rope and Magnetic Hole in the Earth's Magnetosheath

AbstractWe report in situ observation of magnetic reconnection between magnetic flux rope (MFR) and magnetic hole (MH) in the magnetosheath by the Magnetospheric Multiscale mission. The MFR was rooted in the magnetopause and could be generated by magnetopause reconnection therein. A thin current sheet was generated due to the interaction between MFR and MH. The sub‐Alfvénic ion bulk flow and the Hall field were detected inside this thin current sheet, indicating an ongoing reconnection. An elongated electron diffusion region characterized by non‐frozen‐in electrons, magnetic‐to‐particle energy conversion, and crescent‐shaped electron distribution was detected in the reconnection exhaust. The observation provides a mechanism for the dissipation of MFRs and thus opens a new perspective on the evolution of MFRs at the magnetopause. Our work also reveals one potential fate of the MHs in the magnetosheath which could reconnect with the MFRs and further merge into the magnetopause.

In Situ Observations of Magnetic Reconnection Caused by the Interactions of Two Dipolarization Fronts

AbstractUsing high‐resolution data from the Magnetospheric Multiscale mission, an electron‐only reconnection current sheet is found between two successive dipolarization fronts (DFs). The electron‐only reconnection occurs between the northward component of the magnetic field of the flux pileup region (FPR) of the first DF (DF1) and the southward component of the magnetic dip of the second DF (DF2). The faster DF2 compresses the FPR of DF1, which constitutes an anti‐parallel topology and reduces the thickness of the current sheet. Further analysis shows that the current sheet is unstable to the electron tearing instability, which may power the onset of the reconnection. Our results suggest that these two DFs may merge into one by the reconnection, which sheds light on the evolution of DFs during their earthward propagation.

Radiative properties of plasmoids and plasmoid mergers in magnetic reconnection

ABSTRACT Magnetic reconnection is often considered as the primary particle acceleration mechanism in a magnetized blazar zone environment. The majority of radiation in the reconnection layer comes from plasmoids and their mergers. In particular, plasmoid mergers can produce strong multiwavelength flares and major variations in synchrotron polarization signatures. However, radiative properties of plasmoid mergers have not been well explored due to difficulties in tracking the merging processes. Here we use an image processing method that combines the magnetic vector potential and density to identify isolated and merging plasmoids. We find that this method can clearly distinguish radiation contributions from isolated plasmoids, merging plasmoids, and the primary current sheet of reconnection. This new method enables us to study the radiative properties of plasmoids and mergers statistically. Our results show that isolated plasmoids have similar emissivity regardless of their sizes, and they generally have non-zero polarization degree (PD) due to their quasi-circular shape. Flares due to plasmoid mergers have relative amplitudes that are antiproportional to the size ratio of the plasmoids participating in the mergers. Finally, only mergers between plasmoids of comparable sizes (width ratio ≲5) can lead to significant spectral hardening and polarization angle (PA) variations; the amplitude of the PA variations is between 0 and 180° and has a mean value of 90°. Our analyses on 2D simulations can pave the way for future analyses and machine learning techniques on radiative properties of 3D magnetic reconnection simulations.

Causality Analysis Between Exchange Rate, Current Balance Sheet, Inflation, and Gross Domestic Product in ASEAN-5 1980-2022

This research investigates the causality between exchange rate, current balance sheet, inflation, and gross domestic product in ASEAN 5 from 1980 to 2022. The method employs the Granger causality test. This research finds weak evidence of a J-curve effect on the current account balance in Indonesia because empirical results with several tests and models reject the J-curve hypothesis and do not find evidence of an influence of the rupiah exchange rate on Indonesia's current account balance in the long term so that it can the conclusion is drawn that: (1) There is no causal relationship between the current account balance and the exchange rate in Indonesia from 1996-2022; (2) Changes in exchange rates affect changes in the current account balance in the short and long term; (3) The mechanism for changes in the current account deficit does not affect changes in the exchange rate

Kinetic‐Scale Current Sheets in the Solar Wind at 5 AU

AbstractWe present statistical analysis of 16,903 current sheets (CSs) observed over 641 days aboard Ulysses spacecraft at 5 AU. We show that the magnetic field rotates across CSs through some shear angle, while only weakly varies in magnitude. The CSs are typically asymmetric with statistically different, though only by a few percent, magnetic field magnitudes at the CS boundaries. The data set is classified into about 90.6% non‐bifurcated and 9.4% bifurcated CSs. Most of the CSs are proton kinetic‐scale structures with the half‐thickness of non‐bifurcated and bifurcated CSs within respectively 200–2,000 km and 500–5,000 km or 0.5–5λp and 0.7–15λp in units of local proton inertial length. The amplitude of the current density, mostly parallel to magnetic field, is typically within 0.05–0.5 nA/m2 or 0.04–0.4JA in units of local Alfvén current density. The CSs demonstrate approximate scale‐invariance with the shear angle and current density amplitude scaling with the half‐thickness, and . The matching of the magnetic field rotation and compressibility observed within the CSs against those in ambient solar wind indicate that the CSs are produced by turbulence, inheriting its scale‐invariance and compressibility. The estimated asymmetry in plasma beta between the CS boundaries is shown to be insufficient to suppress magnetic reconnection through the diamagnetic drift of X‐line. The presented results will be of value for future comparative analysis of CSs observed at different distances from the Sun.

Current Sheet Alignment in Oblique Black Hole Magnetospheres: A Black Hole Pulsar?

We study the magnetospheric evolution of a nonaccreting spinning black hole (BH) with an initially inclined split monopole magnetic field by means of 3D general relativistic magnetohydrodynamic simulations. This serves as a model for a neutron star (NS) collapse or a BH–NS merger remnant after the inherited magnetosphere has settled into a split monopole field creating a striped wind. We show that the initially inclined split monopolar current sheet aligns over time with the BH equatorial plane. The inclination angle evolves exponentially toward alignment, with an alignment timescale that is inversely proportional to the square of the BH angular velocity, where higher spin results in faster alignment. Furthermore, magnetic reconnection in the current sheet leads to exponential decay of event-horizon-penetrating magnetic flux with nearly the same timescale for all considered BH spins. In addition, we present relations for the BH mass and spin in terms of the period and alignment timescale of the striped wind. The explored scenario of a rotating, aligning, and reconnecting current sheet can potentially lead to multimessenger electromagnetic counterparts to a gravitational-wave event due to the acceleration of particles powering high-energy radiation, plasmoid mergers resulting in coherent radio signals, and pulsating emission due to the initial misalignment of the BH magnetosphere.

Plasma Sheet Counterparts for Auroral Beads and Vortices in Advance of Fast Flows: New Evidence for Near‐Earth Substorm Onset

AbstractThe relationship between auroral, ground, and plasma sheet signatures in the late growth phase is crucial for understanding the sequence of events during a substorm expansion phase onset. Here we show conjugate ground‐auroral‐satellite observations of a substorm that occurred on 18 September 2021, between 04:45 and 05:00 UT, where four auroral activations were detected in the all‐sky imagers. An initial activation showed the brightening of an equatorward arc within the cutoff of the 630 nm emissions, indicating activity on closed field lines well inside the open‐closed field line boundary (OCFLB). During a second activation, auroral beads were observed on a brightening arc, equatorward and within the OCFLB, followed by the transformation from small‐scale to large‐scale vortices. The tail current sheet was highly disturbed during the auroral vortex evolution, including pressure and magnetic disturbances, an apparent broadening of a previously thin current sheet, and a breakdown of the frozen‐in condition. Our observations clearly show late growth phase dynamics, including arc brightenings, the formation of auroral beads, and auroral vortex development, can occur well in advance of fast Earthward flows in the tail. Indeed, it is only during that later activity that auroral breakup and strong Earthward flows, which we associate with magnetic reconnection further down the tail, are observed together with strong magnetic bays on the ground. The sequence of events is consistent with an inside‐to‐outside model at substorm expansion phase onset, most likely via a shear‐flow ballooning instability in the transition region from dipole to tail‐like fields in the near‐Earth plasma sheet.

Revisiting flares in Sagittarius A* based on general relativistic magnetohydrodynamic numerical simulations of black hole accretion

ABSTRACT High-resolution observations with GRAVITY-Very Large Telescope Interferometer (VLTI) instrument have provided abundant information about the flares in Sgr A*, the supermassive black hole in our Galactic centre, including the time-dependent location of the centroid (a ‘hotspot’), the light curve, and polarization. Yuan et al. (2009) proposed a ‘coronal mass ejection’ model to explain the flares and their association with the plasma ejection. The key idea is that magnetic reconnection in the accretion flow produces the flares and results in the formation and ejection of flux ropes. The dynamical process proposed in the model has been confirmed by three-dimensional general-relativistic magnetohydrodynamic simulations in a later work. Based on this scenario, in our previous works the radiation of the flux rope has been calculated analytically and compared to the observations. In the present paper, we develop the model by directly using numerical simulation data to interpret observations. We first identify flux ropes formed due to reconnection from the data. By assuming that electrons are accelerated in the reconnection current sheet and flow into the flux rope and emit their radiation there, we have calculated the time-dependent energy distribution of electrons after phenomenologically considering their injection due to reconnection acceleration, radiative and adiabatic cooling. The radiation of these electrons is calculated using the ray-tracing approach. The trajectory of the hotspot, the radiation light curve during the flare, and the polarization are calculated. These results are compared with the GRAVITY observations and good consistencies are found.

Tearing-mediated Reconnection in Magnetohydrodynamic Poorly Ionized Plasmas. I. Onset and Linear Evolution

In high-Lundquist-number plasmas, reconnection proceeds via the onset of tearing, followed by a nonlinear phase during which plasmoids continuously form, merge, and are ejected from the current sheet (CS). This process is understood in fully ionized, magnetohydrodynamic plasmas. However, many plasma environments, such as star-forming molecular clouds and the solar chromosphere, are poorly ionized. We use theory and computation to study tearing-mediated reconnection in such poorly ionized systems. In this paper, we focus on the onset and linear evolution of this process. In poorly ionized plasmas, magnetic nulls on scales below v A,n0/ν ni0, with v A,n0 the neutral Alfvén speed and ν ni0 the neutral–ion collision frequency, will self-sharpen via ambipolar diffusion. This sharpening occurs at an increasing rate, inhibiting the onset of reconnection. Once the CS becomes thin enough, however, ions decouple from neutrals and the thinning of the CS slows, allowing the onset of tearing in a time of order νni0−1 . We find that the wavelength and growth rate of the mode that first disrupts the forming sheet can be predicted from a poorly ionized tearing dispersion relation; as the plasma recombination rate increases and ionization fraction decreases, the growth rate becomes an increasing multiple of ν ni0 and the wavelength becomes a decreasing fraction of v A,n0/ν ni0.

Magnetospheric Sources of Theta Aurora: A Case Study Comparing Observations With SWMF Global Simulation

AbstractWe present the first high resolution global MHD with coupled inner magnetosphere simulation results of an observed theta aurora event. We use the Space Weather Modeling Framework in the Geospace configuration, which produces accurate field aligned current closure in the ionosphere that is integral to theta aurora formation. At the location of the observed theta aurora, the simulation produces a narrow channel of Joule heating along both open and closed field lines, and between a pair of oppositely directed field‐aligned current sheets in the ionosphere. We demonstrate that this Joule heating pattern that we identify as theta aurora maps to a reconnection region at the magnetotail flanks as well as in the distant magnetotail. The theta aurora maps to a cross‐tail current disruption and field‐aligned current source region in a highly twisted magnetotail.