Colby Haggerty

Colby Haggerty
University of Chicago | UC

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30
Publications
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1,108
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Publications

Publications (30)
Article
Full-text available
We report Magnetospheric Multiscale four-spacecraft observations of a thin reconnecting current sheet with weakly asymmetric inflow conditions and a guide field of approximately twice the reconnecting magnetic field. The event was observed at the interface of interlinked magnetic field lines at the flank magnetopause when the maximum spacecraft sep...
Preprint
Full-text available
We study the nature of pressure-strain interaction at reconnection sites, detected by NASA's Magnetospheric Multiscale (MMS) Mission. We employ data from a series of published case studies, including a large-scale reconnection event at the magnetopause, three small-scale reconnection events at the magnetosheath current sheets, and one example of th...
Article
Full-text available
We study the nature of pressure-strain interaction at reconnection sites detected by NASA's Magnetospheric Multiscale Mission. We employ data from a series of previously published case studies, including a large-scale reconnection event at the magnetopause, three small-scale reconnection events at the magnetosheath current sheets, and one example o...
Article
Using 2.5 dimensional kinetic particle-in-cell simulations, we simulate reconnection conditions appropriate for the magnetosheath and solar wind, i.e., plasma beta (ratio of gas pressure to magnetic pressure) greater than 1 and low magnetic shear (strong guide field). Changing the simulation domain size, we find that the ion response varies greatly...
Article
Full-text available
Change history: In this Letter, the y-axis values in Fig. 3f should go from 4 to −8 (rather than from 4 to −4), the y-axis values in Fig. 3h should appear next to the major tick marks (rather than the minor ticks), and in Fig. 1b, the arrows at the top and bottom of the electron-scale current sheet were going in the wrong direction; these errors ha...
Article
Full-text available
Plain Language Summary The Earth and the solar wind magnetic fields interconnect through a process called magnetic reconnection. The newly reconnected magnetic field lines are strongly bent and accelerate particles, similar to a rubber band in a slingshot. In this paper we have used observations from NASA's Magnetospheric MultiScale spacecraft to i...
Preprint
Using kinetic particle-in-cell (PIC) simulations, we simulate reconnection conditions appropriate for the magnetosheath and solar wind, i.e., plasma beta (ratio of gas pressure to magnetic pressure) greater than 1 and low magnetic shear (strong guide field). Changing the simulation domain size, we find that the ion response varies greatly. For reco...
Article
The outflow velocity of jets produced by collisionless magnetic reconnection is shown to be reduced by the ion exhaust temperature in fully kinetic particle in cell simulations and in situ satellite observations. We derive a scaling relationship for the outflow velocity based on the upstream Alfvén speed and the parallel ion exhaust temperature, wh...
Article
Full-text available
Analysis of high-resolution Magnetospheric Multiscale Mission plasma and magnetic field data directly reveals the exchanges of energy between electromagnetic and flow energy and between microscopic flows and random kinetic energy in the inhomogeneous turbulent magnetosheath. The computed rates of exchange are based on exact results from the collisi...
Article
Full-text available
Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region1,2. On larger scales, ions couple to the newly reconnected magnetic-field lines and are...
Preprint
Full-text available
The outflow velocity of jets produced by collisionless magnetic reconnection is shown to be reduced by the ion exhaust temperature in simulations and observations. We derive a scaling relationship for the outflow velocity based on the upstream Alfv\'en speed and the parallel ion exhaust temperature, which is verified in kinetic simulations and obse...
Article
Full-text available
Magnetospheric Multiscale observations are used to probe the structure and temperature profile of a guide field reconnection exhaust ~100 ion inertial lengths downstream from the X-line in the Earth's magnetosheath. Asymmetric Hall electric and magnetic field signatures were detected, together with a density cavity confined near 1 edge of the exhau...
Article
Full-text available
We present a study of signatures of energy dissipation at kinetic scales in plasma turbulence based on observations by the Magnetospheric Multiscale mission (MMS) in the Earth's magnetosheath. Using several intervals, and taking advantage of the high-resolution instrumentation on board MMS, we compute and discuss several statistical measures of coh...
Article
Dissipation of plasma turbulent energy is a phenomenon having significant implications for the heating of the solar corona and solar wind. While processes involving linear wave damping, stochastic heating, and reconnection have been postulated as contributors to heating mechanisms, the relative role that they play is not currently understood. In th...
Article
The quadrupolar out-of-plane Hall magnetic field generated during collisionless reconnection propagates away from the x-line as a kinetic Alfvén wave (KAW). While it has been shown that this KAW carries substantial Poynting flux and propagates super-Alfvenically, how this KAW damps as it propagates away from the x-line is not well understood. In th...
Article
We report three spacecraft observations of a reconnecting magnetosheath current sheet with a guide field of unity, with THD and THE/THA observing oppositely directed reconnection exhausts, indicating the presence of an X-line between the spacecraft. The near constant convective speed of the magnetosheath current sheet allowed the direct translation...
Article
Magnetic reconnection is a ubiquitous phenomenon in turbulent plasmas. It is an important part of the turbulent dynamics and heating of space and astrophysical plasmas. We examine the statistics of magnetic reconnection using a quantitative local analysis of the magnetic vector potential, previously used in magnetohydrodynamics simulations, and now...
Article
Full-text available
Kinetic plasma turbulence cascade spans multiple scales ranging from macroscopic fluid flow to sub-electron scales. Mechanisms that dissipate large scale energy, terminate the inertial range cascade and convert kinetic energy into heat are hotly debated. Here we revisit these puzzles using fully kinetic simulation. By performing scale-dependent spa...
Article
Full-text available
Observations made using the Wind spacecraft of Hall magnetic fields in solar wind reconnection exhausts are presented. These observations are consistent with the generation of Hall fields by a narrow ion inertial scale current layer near the separatrix, which is confirmed with an appropriately scaled particle-in-cell simulation that shows excellent...
Article
We report a THEMIS-D spacecraft crossing of a magnetopause reconnection exhaust ~9 ion skin depths (di) downstream of an X-line. The crossing was characterized by ion jetting at speeds substantially below the predicted reconnection outflow speed. In the magnetospheric inflow region THEMIS detected (a) penetration of magnetosheath ions and the resul...
Article
Full-text available
New Magnetospheric Multiscale (MMS) observations of small-scale (~7 ion inertial length radius) flux transfer events (FTEs) at the dayside magnetopause are reported. The 10km MMS tetrahedron size enables their structure and properties to be calculated using a variety of multispacecraft techniques, allowing them to be identified as flux ropes, whose...
Article
We report evidence for reconnection between colliding reconnection jets in a compressed current sheet at the center of a magnetic flux rope at Earth's magnetopause. The reconnection involved nearly symmetric inflow boundary conditions with a strong guide field of two. The thin (2.5 ion-skin depth (di) width) current sheet (at ~12 di downstream of t...
Article
Kinetic particle-in-cell simulations are used to identify signatures of the electron diffusion region (EDR) and its surroundings during asymmetric magnetic reconnection. A "shoulder" in the sunward pointing normal electric field (EN > 0) at the reconnection magnetic field reversal is a good indicator of the EDR, and is caused by magnetosheath elect...
Article
The physical processes that control the partition of released magnetic energy between electrons and ions during reconnection is explored through particle-in-cell simulations and analytical techniques. We demonstrate that the development of a large-scale parallel electric field and its associated potential controls the relative heating of electrons...
Article
Ion heating due to magnetic reconnection is an important process with applications to diverse plasmas, but previous simulations and observations have measured heating less than half oftheoretical predictions. Using kinetic particle-in-cell simulations, we show that this heating reduction is due to the presence of large scale parallel electric field...
Article
Full-text available
Electron bulk heating during magnetic reconnection with symmetric inflow conditions is examined using kinetic particle-in-cell (PIC) simulations. The degree of electron heating is well correlated with the inflowing Alfv\'en speed $c_{Ar}$ based on the reconnecting magnetic field through the relation $\Delta T_e = 0.033 \,m_i\,c_{Ar}^2$, where $\Del...
Article
In order to determine the amount of mass lost from a star which just fills its Roche Lobe, it is imperative to accurately calculate the size of the nozzle -- the area through which the mass flows. This is normally bounded by the equipotential surface where the density of the exponential atmosphere drops by one scale height. When the stars are in an...
Article
We calculate the instantaneous mass loss rate of a nearly-semi-detached donor star in an eccentric orbit about its companion by taking into account the varying size and shape of the donor's Roche Lobe throughout the orbit. As in the circular case, we model the density of the stellar atmosphere as a decreasing exponential function of the instantaneo...