Interplanetary Shock‐induced Magnetopause Motion: Comparison between Theory and Global Magnetohydrodynamic Simulations

One of the most promising methods of research in solar–terrestrial physics is the comparison of the responses of the magnetosphere–ionosphere–atmosphere system to various types of interplanetary disturbances (so-called “interplanetary drivers”). Numerous studies have shown that different types of drivers result in different reactions of the system for identical variations in the interplanetary magnetic field. In particular, the sheaths—compression regions before fast interplanetary CMEs (ICMEs)—have higher efficiency in terms of the generation of magnetic storms than ICMEs. The growing popularity of this method of research is accompanied by the growth of incorrect methodological approaches in such studies. These errors can be divided into four main classes: (i) using incorrect data with the identification of driver types published in other studies; (ii) using incorrect methods to identify the types of drivers and, as a result, misclassify the causes of magnetospheric-ionospheric disturbances; (iii) ignoring a frequent case with a complex, composite, nature of the driver (the presence of a sequence of several simple drivers) and matching the system response with only one of the drivers; for example, a magnetic storm is often generated by a sheath in front of ICME, although the authors consider these events to be a so-called “CME-induced” storm, rather than a “sheath-induced” storm; (iv) ignoring the compression regions before the fast CME in the case when there is no interplanetary shock (IS) in front of the compression region (“sheath without IS” or the so-called “lost driver”), although this type of driver generates about 10% of moderate and large magnetic storms. Possible ways of solving this problem are discussed.

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Unusual enhancement of ~ 30 MeV proton flux in an ICME sheath region

Earth Planets and Space ◽

10.1186/s40623-021-01362-y ◽

2021 ◽

Vol 73 (1) ◽

Author(s):

Mitsuo Oka ◽

Takahiro Obara ◽

Nariaki V. Nitta ◽

Seiji Yashiro ◽

Daikou Shiota ◽

...

Keyword(s):

Shock Front ◽

Energetic Particle ◽

Leading Edge ◽

Solar Energetic Particle ◽

Interplanetary Shock ◽

Proton Event ◽

Sheath Region ◽

Time Profiles ◽

Energetic Particle Flux ◽

Mev Protons

AbstractIn gradual Solar Energetic Particle (SEP) events, shock waves driven by coronal mass ejections (CMEs) play a major role in accelerating particles, and the energetic particle flux enhances substantially when the shock front passes by the observer. Such enhancements are historically referred to as Energetic Storm Particle (ESP) events, but it remains unclear why ESP time profiles vary significantly from event to event. In some cases, energetic protons are not even clearly associated with shocks. Here, we report an unusual, short-duration proton event detected on 5 June 2011 in the compressed sheath region bounded by an interplanetary shock and the leading edge of the interplanetary CME (or ICME) that was driving the shock. While < 10 MeV protons were detected already at the shock front, the higher-energy (> 30 MeV) protons were detected about four hours after the shock arrival, apparently correlated with a turbulent magnetic cavity embedded in the ICME sheath region.

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3D magnetized jet break-out from neutron-star binary merger ejecta: afterglow emission from the jet and the ejecta

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab115 ◽

2021 ◽

Vol 502 (2) ◽

pp. 1843-1855

Author(s):

Antonios Nathanail ◽

Ramandeep Gill ◽

Oliver Porth ◽

Christian M Fromm ◽

Luciano Rezzolla

Keyword(s):

Neutron Star ◽

Thermal Emission ◽

Opening Angle ◽

Hollow Core ◽

Binary Neutron Star ◽

Vlbi Observations ◽

Superluminal Motion ◽

General Relativistic ◽

Star Binary ◽

Magnetohydrodynamic Simulations

ABSTRACT We perform 3D general-relativistic magnetohydrodynamic simulations to model the jet break-out from the ejecta expected to be produced in a binary neutron-star merger. The structure of the relativistic outflow from the 3D simulation confirms our previous results from 2D simulations, namely, that a relativistic magnetized outflow breaking out from the merger ejecta exhibits a hollow core of θcore ≈ 4°, an opening angle of θjet ≳ 10°, and is accompanied by a wind of ejected matter that will contribute to the kilonova emission. We also compute the non-thermal afterglow emission of the relativistic outflow and fit it to the panchromatic afterglow from GRB170817A, together with the superluminal motion reported from VLBI observations. In this way, we deduce an observer angle of $\theta _{\rm obs}= 35.7^{\circ \, \, +1.8}_{\phantom{\circ \, \, }-2.2}$. We further compute the afterglow emission from the ejected matter and constrain the parameter space for a scenario in which the matter responsible for the thermal kilonova emission will also lead to a non-thermal emission yet to be observed.

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Magnetohydrodynamic simulations of gamma-ray burst jets: Beyond the progenitor star

New Astronomy ◽

10.1016/j.newast.2010.03.001 ◽

2010 ◽

Vol 15 (8) ◽

pp. 749-754 ◽

Cited By ~ 108

Author(s):

Alexander Tchekhovskoy ◽

Ramesh Narayan ◽

Jonathan C. McKinney

Keyword(s):

Gamma Ray ◽

Gamma Ray Burst ◽

Magnetohydrodynamic Simulations

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Dynamics of the plasma sheet in the near-Earth magnetotail by the impact of an interplanetary shock

Journal of the Korean Physical Society ◽

10.1007/s40042-021-00187-y ◽

2021 ◽

Author(s):

Hee-Eun Kim ◽

Ensang Lee

Keyword(s):

Plasma Sheet ◽

Interplanetary Shock ◽

The Impact

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Cluster observations of sudden impulses in the magnetotail caused by interplanetary shocks and pressure increases

Annales Geophysicae ◽

10.5194/angeo-23-609-2005 ◽

2005 ◽

Vol 23 (2) ◽

pp. 609-624 ◽

Cited By ~ 26

Author(s):

K. E. J. Huttunen ◽

J. Slavin ◽

M. Collier ◽

H. E. J. Koskinen ◽

A. Szabo ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Dynamic Pressure ◽

Solar Wind Speed ◽

Interplanetary Shock ◽

Wind Pressure ◽

Shock Propagation ◽

Interplanetary Shocks ◽

Maximum Variance ◽

The Magnetic Field

Abstract. Sudden impulses (SI) in the tail lobe magnetic field associated with solar wind pressure enhancements are investigated using measurements from Cluster. The magnetic field components during the SIs change in a manner consistent with the assumption that an antisunward moving lateral pressure enhancement compresses the magnetotail axisymmetrically. We found that the maximum variance SI unit vectors were nearly aligned with the associated interplanetary shock normals. For two of the tail lobe SI events during which Cluster was located close to the tail boundary, Cluster observed the inward moving magnetopause. During both events, the spacecraft location changed from the lobe to the magnetospheric boundary layer. During the event on 6 November 2001 the magnetopause was compressed past Cluster. We applied the 2-D Cartesian model developed by collier98 in which a vacuum uniform tail lobe magnetic field is compressed by a step-like pressure increase. The model underestimates the compression of the magnetic field, but it fits the magnetic field maximum variance component well. For events for which we could determine the shock normal orientation, the differences between the observed and calculated shock propagation times from the location of WIND/Geotail to the location of Cluster were small. The propagation speeds of the SIs between the Cluster spacecraft were comparable to the solar wind speed. Our results suggest that the observed tail lobe SIs are due to lateral increases in solar wind dynamic pressure outside the magnetotail boundary.

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Constraining the coherence scale of the interstellar magnetic field using TeV gamma-ray observations of supernova remnants

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1678 ◽

2020 ◽

Vol 496 (2) ◽

pp. 2448-2461 ◽

Cited By ~ 2

Author(s):

Matteo Pais ◽

Christoph Pfrommer ◽

Kristian Ehlert ◽

Maria Werhahn ◽

Georg Winner

Keyword(s):

Magnetic Field ◽

Interstellar Medium ◽

Supernova Remnants ◽

Gamma Ray ◽

Galactic Cosmic Rays ◽

Shock Acceleration ◽

Interstellar Gas ◽

Narrow Angle ◽

Magnetohydrodynamic Simulations ◽

Tev Gamma Rays

ABSTRACT Galactic cosmic rays (CRs) are believed to be accelerated at supernova remnant (SNR) shocks. In the hadronic scenario, the TeV gamma-ray emission from SNRs originates from decaying pions that are produced in collisions of the interstellar gas and CRs. Using CR-magnetohydrodynamic simulations, we show that magnetic obliquity-dependent shock acceleration is able to reproduce the observed TeV gamma-ray morphology of SNRs such as Vela Jr and SN1006 solely by varying the magnetic morphology. This implies that gamma-ray bright regions result from quasi-parallel shocks (i.e. when the shock propagates at a narrow angle to the upstream magnetic field), which are known to efficiently accelerate CR protons, and that gamma-ray dark regions point to quasi-perpendicular shock configurations. Comparison of the simulated gamma-ray morphology to observations allows us to constrain the magnetic coherence scale λB around Vela Jr and SN1006 to $\lambda _B \simeq 13_{-4.3}^{+13}$ pc and $\lambda _B \gt 200_{-40}^{+50}$ pc, respectively, where the ambient magnetic field of SN1006 is consistent with being largely homogeneous. We find consistent pure hadronic and mixed hadronic-leptonic models that both reproduce the multifrequency spectra from the radio to TeV gamma-rays and match the observed gamma-ray morphology. Finally, to capture the propagation of an SNR shock in a clumpy interstellar medium, we study the interaction of a shock with a dense cloud with numerical simulations and analytics. We construct an analytical gamma-ray model for a core collapse SNR propagating through a structured interstellar medium, and show that the gamma-ray luminosity is only biased by 30 per cent for realistic parameters.

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