Turbulent Cosmic Ray–Mediated Shocks in the Hot Ionized Interstellar Medium

Wang, Bingbing; Zank, G. P.; Zhao, Lingling; Adhikari, L.

doi:10.3847/1538-4357/ac6ddc

Cited by 15 publications

(4 citation statements)

References 60 publications

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“…The data also show that the magnitude of the magnetic field intensifies before the transition, likely as a result of shock mediation by energetic particles. This amplification of the magnetic field and the intensification of the relative fluctuations is also predicted by theoretical models of strictly parallel shocks (e.g., Wang et al 2022). The shock transition is characterized by δB/B 0.5, preceding the ramp-overshoot region, which exhibits δB/B 2.…”

Section: One Of the Fastest Ip Shocks Observed In Situ To Datesupporting

confidence: 69%

Acceleration of Electrons and Ions by an “Almost” Astrophysical Shock in the Heliosphere

Jebaraj,

Agapitov,

Krasnoselskikh

et al. 2024

ApJL

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Collisionless shock waves, ubiquitous in the Universe, are crucial for particle acceleration in various astrophysical systems. Currently, the heliosphere is the only natural environment available for their in situ study. In this work, we showcase the collective acceleration of electrons and ions by one of the fastest in situ shocks ever recorded, observed by the pioneering Parker Solar Probe at only 34.5 million km from the Sun. Our analysis of this unprecedented, near-parallel shock shows electron acceleration up to 6 MeV amidst intense multiscale electromagnetic wave emissions. We also present evidence of a variable shock structure capable of injecting and accelerating ions from the solar wind to high energies through a self-consistent process. The exceptional capability of the probe’s instruments to measure electromagnetic fields in a shock traveling at 1% the speed of light has enabled us, for the first time, to confirm that the structure of a strong heliospheric shock aligns with theoretical models of strong shocks observed in astrophysical environments. This alignment offers viable avenues for understanding astrophysical shock processes and the self-consistent acceleration of charged particles.

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Section: One Of the Fastest Ip Shocks Observed In Situ To Datesupporting

confidence: 69%

Acceleration of Electrons and Ions by an “Almost” Astrophysical Shock in the Heliosphere

Jebaraj,

Agapitov,

Krasnoselskikh

et al. 2024

ApJL

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“…For example, the perpendicular diffusion coefficients will increase as the magnetic turbulence is enhanced near termination shocks, leading to the variation of the precursor for the shock. Similar to the work by Wang et al (2022), a more sophiscated model with the turbulence embedded is needed for the future work, even under a context of global MHD simulation. This improved treatment will help for a better understanding with the effects of ACRs on the solar wind events in the outer heliosphere.…”

Section: Comparison Results With Voyagermentioning

confidence: 99%

Effects of anomalous cosmic rays on the solar wind events in the outer heliosphere

Zhou,

Guo,

Wang

2024

Front. Astron. Space Sci.

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Anomalous cosmic-rays (ACRs) are thought to be originated from the acceleration of pickup ions (PUIs) at the termination shock or interplanetary shocks, and play important role for the plasma dynamics in the outer heliosphere. Due to limited observation, the effects of ACRs on the solar wind events is not well known. Under the approximation of spherical symmetry, we have developed a three-component magneto-hydrodynamic (MHD) numerical model that contains solar wind plasma, interstellar neutral atoms and ACRs, to investigate the evolution of the solar wind within a heliocentric distance from 1 to 150 astronomical units (AU). We use the solar wind observations from the OMNI database with the time from 2010.5 to 2016.0 (decimal years) at the inner boundary, and the effect of ACRs on the propagation of the solar wind events are compared with the observations from the spacecrafts of New Horizons, Voyager 1 and 2. The results show that ACRs may decrease the speed of the solar wind shocks to some extent, and the effect is positively correlated with the diffusion coefficient; a larger diffusion coefficient leads to a more pronounced effect. Moreover, the ACRs has a dissipation effect on the shock-like solar wind structures, and may play important roles on the dynamics of solar wind in the outer heliosphere.

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“…Mostafavi et al (2018) find the heliospheric termination shock to be formed and dominated by processes in the pickup ions rather than the (quasi-)thermal plasma. Wang et al (2022b) consider a similar problem with application to supernova remnant shock waves in the interstellar medium, using a coupled system of equations to describe the gas, cosmic rays, and turbulence, based in part on works cited above. Both sets of authors find that the shock discontinuity disappears and that the transition between upstream and downstream is broadened.…”

Section: Discussionmentioning

confidence: 99%

Critical Mach Numbers for Magnetohydrodynamic Shocks with Accelerated Particles and Waves

Laming

2022

ApJ

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The first critical fast Mach number is defined for a magnetohydrodynamic shock as the Mach number where the shock transitions from subcritical, laminar behavior to supercritical behavior, characterized by incident ion reflection from the shock front. The ensuing upstream waves and turbulence are convected downstream, leading to a turbulent shock structure. Formally, this is the Mach number where plasma resistivity can no longer provide sufficient dissipation to establish a stable shock, and is characterized by the downstream flow speed becoming subsonic. We revisit these calculations, including in the MHD jump conditions terms modeling the plasma energy loss to accelerated particles and the presence of waves associated with these particles. The accelerated particle contributions make an insignificant change, but the associated waves have a more important effect. Upstream waves can be strongly amplified in intensity on passing through the shock, and they represent another means of shock dissipation. The presence of such waves therefore increases the first critical fast Mach number, especially at quasi-parallel shock where wave excitation is strongest. These effects may have significance for the solar regions where shock waves accelerate particles and cause Type II and Type III radio bursts, and they could also contribute to the event-to-event variability of SEP acceleration.

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Turbulent Cosmic Ray–Mediated Shocks in the Hot Ionized Interstellar Medium

Cited by 15 publications

References 60 publications

Acceleration of Electrons and Ions by an “Almost” Astrophysical Shock in the Heliosphere

Acceleration of Electrons and Ions by an “Almost” Astrophysical Shock in the Heliosphere

Effects of anomalous cosmic rays on the solar wind events in the outer heliosphere

Critical Mach Numbers for Magnetohydrodynamic Shocks with Accelerated Particles and Waves

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