The microphysics of collisionless shock waves

Marcowith, A.; Bret, Antoine; Bykov, A. M.; Dieckman, M. E.; Drury, L. O'c.; Lembège, Bertrand; Lemoine, Martin; Morlino, G.; Murphy, Gareth; Pelletier, G.; Plotnikov, Illya; Reville, Brian; Riquelme, Mario; Sironi, Lorenzo; Novo, Anne Stockem

doi:10.1088/0034-4885/79/4/046901

Cited by 250 publications

(199 citation statements)

References 475 publications

(868 reference statements)

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“…We here classify gamma-ray binaries as those systems where most of the electromagnetic output of the system is at gamma-ray energies. In order to generate gamma-rays, non-thermal emission mechanisms are required such as the particle acceleration in a shock between the wind from a rapidly rotating neutron star and its companion (Dubus 2006), where the Fermi mechanism (Marcowith et al 2016) may accelerate particles to high energies, or in the highvelocity jets from an accreting black-hole "microquasar" (e.g. Mirabel & Rodríguez 1998).…”

Section: Introductionmentioning

confidence: 99%

A Luminous Gamma-Ray Binary in the Large Magellanic Cloud

Corbet

Chomiuk

Coe

et al. 2016

ApJ

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Gamma-ray binaries consist of a neutron star or a black hole interacting with a normal star to produce gamma-ray emission that dominates the radiative output of the system. Only a handful of such systems have been previously discovered, all within our Galaxy. Here we report the discovery with the Fermi Large Area Telescope (LAT) of a luminous gamma-ray binary in the Large Magellanic Cloud from a search for periodic modulation in all sources in the third Fermi LAT catalog. This is the first such system to be found outside the Milky Way. The system has an orbital period of 10.3 days and is associated with a massive O5III star located in the supernova remnant DEM L241, previously identified as the candidate high-mass X-ray binary (HMXB) CXOU J053600.0-673507. X-ray and radio emission are also modulated on the 10.3 day period, but are in anti-phase with the gamma-ray modulation. Optical radial velocity measurements suggest that the system contains a neutron star. The source is significantly more luminous than similar sources in the Milky Way at radio, optical, X-ray and gamma-ray wavelengths. The detection of this extra-galactic system, but no new Galactic systems raises the possibility that the predicted number of gamma-ray binaries in our Galaxy have been overestimated, and that HMXBs may be born containing relatively slowly rotating neutron stars.

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Section: Introductionmentioning

confidence: 99%

A Luminous Gamma-Ray Binary in the Large Magellanic Cloud

Corbet

Chomiuk

Coe

et al. 2016

ApJ

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“…Collisionless plasmas support energetic structures that are not captured by a single-fluid MHD theory and that can play a vital role in the thermalization of plasma. Examples are magnetosonic solitons [6,7] and the beams of shock-reflected particles ahead of the bow shock [8], which enforce a non-stationarity of the shock [9][10][11][12]. Single-fluid MHD simulations are nevertheless used to solve problems in collisionless plasma based on the argument that they can describe the plasma dynamics on a large enough scale.…”

mentioning

confidence: 99%

Emergence of MHD structures in a collisionless PIC simulation plasma

et al. 2017

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The expansion of a dense plasma into a dilute plasma across an initially uniform perpendicular magnetic field is followed with a one-dimensional particle-in-cell (PIC) simulation over MHD time scales. The dense plasma expands in the form of a fast rarefaction wave. The accelerated dilute plasma becomes separated from the dense plasma by a tangential discontinuity at its back. A fast magnetosonic shock with the Mach number 1.5 forms at its front. Our simulation demonstrates how wave dispersion widens the shock transition layer into a train of nonlinear fast magnetosonic waves. A thermal pressure gradient in a magnetized plasma accelerates the dense plasma towards the dilute one and a rarefaction wave develops. The collision of the expanding plasma with the dilute plasma triggers shocks if the collision speed exceeds the phase velocity of the fastest ion wave. In the rest frame of the shock, the fast-moving upstream plasma is slowed down, compressed and heated as it crosses the shock and moves downstream. This net flux adds material to the downstream plasma, which lets the shock expand into the upstream direction.Shocks have been widely examined due to their key role in regulating the transfer of mass, momentum and energy in plasma. They are most easily described in a one-dimensional geometry. Shock tube experiments [1,2], which enforce such a geometry, examined shocks in partially magnetized and collisional plasma. Particle collisions equilibrate the plasma and macroscopic quantities like flow speed and temperature are uniquely defined. The time-evolution of these quantities is described well by the equations of single-fluid magnetohydrodynamics (MHD) if collisions are frequent enough to establish a thermal equilibrium between electrons and ions on the time scales of interest. Numerical shock tube experiments investigating the thermal expansion of plasma have also been performed in order to test single-fluid MHD codes, since the important MHD shocks emerge under such conditions [3,4].However, not all plasma shocks are collisional. The mean free path of the particles in the plasma, in which the Earth's bow shock [5] is immersed, is large compared to the thickness of its transition layer and it is sustained by electromagnetic fields. Collisionless plasmas support energetic structures that are not captured by a single-fluid MHD theory and that can play a vital role in the thermalization of plasma. Examples are magnetosonic solitons [6,7] and the beams of shock-reflected particles ahead of the bow shock [8], which enforce a non-stationarity of the shock [9-12]. Single-fluid MHD simulations are nevertheless used to solve problems in collisionless plasma based on the argument that they can describe the plasma dynamics on a large enough scale.Here we examine with the particle-in-cell (PIC) code EPOCH [13] the relaxation of a thermal pressure gradient in the presence of a perpendicular magnetic field. We thus perform a numerical shock tube experiment with collisionless plasma to test the hypothesis that the plasma evolut...

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“…The latter is needed to explain the Galactic cosmic ray spectrum observed on Earth (e.g. [19]) as well as the physical nature of complex plasma processes in collisionless shocks which otherwise can not be studied in laboratories [20]. In Figure 3 a simulated 4 keV to 6 keV X-ray image of a supernova shell is presented.…”

Section: Xipe Prospect For Supernova Remnantsmentioning

confidence: 99%

Unveiling the magnetic structure of VHE SNRs/PWNe with XIPE, the x-ray imaging-polarimetry explorer

Oña-Wilhelmi¹,

Vink²,

Bykov³

et al. 2017

AIP Conference Proceedings

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Abstract. The dynamics, energetics and evolution of pulsar wind nebulae (PWNe) and supernova remnants (SNRs), are strongly affected by their magnetic field strength and distribution. They are usually strong, extended, sources of non-thermal X-ray radiation, producing intrinsically polarised radiation. The energetic wind around pulsars produces a highly-magnetised, structured flow, often displaying a jet and a torus and different features (i.e. wisps, knots). This magnetic-dominant wind evolves as it moves away from the pulsar magnetosphere to the surrounding large-scale nebula, becoming kinetic-dominant. Basic aspects such how this conversion is produced, or how the jets and torus are formed, as well as the level of turbulence in the nebula are still unknown. Likewise, the processes ruling the acceleration of particles in shell-like SNRs up to 10 15 eV, including the amplification of the magnetic field, are not clear yet. Imaging polarimetry in this regard is crucial to localise the regions of shock acceleration and to measure the strength and the orientation of the magnetic field at these emission sites. X-ray polarimetry with the X-ray Imaging Polarimetry Explorer (XIPE) will allow the understanding of the magnetic field structure and intensity on different regions in SNRs and PWNe, helping to unveil long-standing questions such as i.e. acceleration of cosmic rays in SNRs or magnetic-to-kinetic energy transfer. SNRs and PWNe also represent the largest population of Galactic very-high energy gamma-ray sources, therefore the study of their magnetic distribution with XIPE will provide fundamental ingredients on the investigation of those sources at very high energies. We will discuss the physics case related to SNRs and PWNe and the expectations of the XIPE observations of some of the most prominent SNRs and PWNe.

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The microphysics of collisionless shock waves

Cited by 250 publications

References 475 publications

A Luminous Gamma-Ray Binary in the Large Magellanic Cloud

A Luminous Gamma-Ray Binary in the Large Magellanic Cloud

Emergence of MHD structures in a collisionless PIC simulation plasma

Unveiling the magnetic structure of VHE SNRs/PWNe with XIPE, the x-ray imaging-polarimetry explorer

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