Connection Between Foreshock Structures and the Generation of Magnetosheath Jets: Vlasiator Results

Suni, Jonas; Palmroth, Minna; Turc, Lucile; Battarbee, Markus; Johlander, Andreas; Tarvus, Vertti; Alho, Markku; Bussov, Maarja; Dubart, Maxime; Ganse, Urs; Grandin, Maxime; Horaites, Konstantinos; Manglayev, Talgat; Papadakis, Konstantinos; Pfau‐Kempf, Yann; Zhou, Hongyang

doi:10.1029/2021gl095655

Cited by 21 publications

(21 citation statements)

References 34 publications

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“…Although several mechanisms have been proposed to explain how jets are generated, their origin is still not understood. Some studies have speculated on the connection of jets to upstream magnetic compressive structures (e.g., SLAMS) 25 – 27 . However, no direct observations have been made so far and the exact causal link has yet to be revealed.…”

Section: Introductionmentioning

confidence: 99%

Downstream high-speed plasma jet generation as a direct consequence of shock reformation

et al. 2022

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Shocks are one of nature’s most powerful particle accelerators and have been connected to relativistic electron acceleration and cosmic rays. Upstream shock observations include wave generation, wave-particle interactions and magnetic compressive structures, while at the shock and downstream, particle acceleration, magnetic reconnection and plasma jets can be observed. Here, using Magnetospheric Multiscale (MMS) we show in-situ evidence of high-speed downstream flows (jets) generated at the Earth’s bow shock as a direct consequence of shock reformation. Jets are observed downstream due to a combined effect of upstream plasma wave evolution and an ongoing reformation cycle of the bow shock. This generation process can also be applicable to planetary and astrophysical plasmas where collisionless shocks are commonly found.

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Section: Introductionmentioning

confidence: 99%

Downstream high-speed plasma jet generation as a direct consequence of shock reformation

et al. 2022

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“…The origin of jets has been discussed much for several years, and many of the points made in previous studies were based on the properties of jets as shown directly through particle moments (see e.g., . However, recently, as shown by simulations and observations (Raptis et al, 2022;Suni et al, 2021), jets appear to be directly connected to the foreshock dynamics for which a fluid approach and the particle moments may provide quite a limited picture (see e.g., Section 6.6 of Paschmann and Daly (1998)). Here, we show that if we consider the jet as an isolated population and perform a series of fits, it exhibits a SW-like profile.…”

Section: Discussionmentioning

confidence: 99%

“…Downstream of the Qpar shock, jets have been associated with several other generation mechanisms, from shock ripples (Hietala et al., 2009; Hietala & Plaschke, 2013) to upstream rotational discontinuities (Archer et al., 2012; Dmitriev & Suvorova, 2012) and reconnection (Preisser et al., 2020). More recently, investigations have focused on the connection of jets to upstream foreshock structures (Karlsson et al., 2015; Omelchenko et al., 2021; Sibeck et al., 2021; Suni et al., 2021) and to the reformation of the Qpar shock (Raptis et al., 2022). While the exact generation mechanism of these structures is still under investigation, the connection to SW properties such as the cone angle and transient events has been demonstrated in various recent studies, indicating that there is a direct link between SW conditions and MSH jets (Koller et al., 2022; LaMoury et al., 2021; Plaschke et al., 2013; Tinoco‐Arenas et al., 2022).…”

Section: Introductionmentioning

confidence: 99%

On Magnetosheath Jet Kinetic Structure and Plasma Properties

Raptis

Karlsson

Vaivads

et al. 2022

Geophysical Research Letters

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As the supersonic solar wind (SW) approaches Earth, it interacts with the planet's magnetic field, forming a bow shock. Downstream of the shock, the magnetosheath (MSH) region forms, which is a highly turbulent plasma environment where several phenomena co-exist. One of these phenomena is the so called MSH jets and during the last two decades, they have drawn considerable attention (Plaschke et al., 2018). These jets are transient dynamic pressure enhancement with respect to the downstream ambient background plasma. The dynamic pressure enhancements can be due to either a velocity and/or density increase (Archer et al., 2012).One of the most important features that determines the properties of jets is whether they are found in the so called Quasi-parallel (Qpar) or Quasi-perpendicular (Qperp) MSH. These regions are, respectively, the plasma downstream of a Qpar or a Qperp shock crossing. Typically, the distinction between Qpar and Qperp shock crossings is based on the angle between the upstream Interplanetary Magnetic Field vector and the bow shock normal vector. If the angle is less than 45°, we call the crossing Qpar, while if it is greater, we call it Qperp. The downstream MSH of the Qpar shocks is more turbulent, exhibits lower temperature anisotropy, and contains more high-energy particles (Fuselier, 1994;Karlsson et al., 2021;. The complexity of Qpar shocks also extends upstream of the shock to the foreshock region where non-linear ULF waves, field-aligned beams and wave-particle interaction regions are observed (

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“…(2015) proposed that HSJs are generated by SLAMSs, a kind of upstream compressive structures with enhanced field magnitude and dynamic pressure. When the SLAMSs or other similar compressive structures penetrate through a dented part of the shock front, they maintain a higher dynamic pressure than the surrounding plasma and become HSJs (Palmroth et al., 2018; Suni et al., 2021). Other foreshock structures, for example, SHFAs (Omidi et al., 2016), and solar wind discontinuities (Archer et al., 2012; Savin et al., 2012), are also potential sources of HSJs.…”

Section: Introductionmentioning

confidence: 99%

Two‐Dimensional Hybrid Simulations of High‐Speed Jets Downstream of Quasi‐Parallel Shocks

Ren,

Lu,

Guo

et al. 2023

JGR Space Physics

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High‐speed jets (HSJs) are frequently observed downstream of a quasi‐parallel bow shock, and they are considered to play important roles in the coupling of the solar wind, the magnetosheath, and the magnetosphere. Using two‐dimensional hybrid simulations, we study the formation of HSJs in quasi‐parallel shocks with different shock angles (θBn). The interaction of the upstream compressive structures that are inhomogeneous in the direction perpendicular to the background magnetic field and the shock front leads to the shock ripples, and then the downstream HSJs. In a parallel shock with the shock angle θBn = 0°, the interaction regions of the upstream compressive structures with the shock front don’t change with time. The shock ripples remain in the same regions of the shock front, and then the HSJs can develop into large‐scale sizes, especially under low plasma β or high Mach number (MA). While in a quasi‐parallel shock with a non‐zero shock angle, the interaction regions of the upstream compressive structures with the shock front move along the shock front. The shock ripples change with time, and the scale size of the downstream HSJs becomes smaller with the increase of the shock angle.This article is protected by copyright. All rights reserved.

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Connection Between Foreshock Structures and the Generation of Magnetosheath Jets: Vlasiator Results

Cited by 21 publications

References 34 publications

Downstream high-speed plasma jet generation as a direct consequence of shock reformation

Downstream high-speed plasma jet generation as a direct consequence of shock reformation

On Magnetosheath Jet Kinetic Structure and Plasma Properties

Two‐Dimensional Hybrid Simulations of High‐Speed Jets Downstream of Quasi‐Parallel Shocks

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