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Nonlinear propagation of stationary large-amplitude electromagnetic (EM) solitary waves in a magnetized electron–positron (EP) plasma is studied using a fully relativistic two-fluid hydrodynamic model. In the first step, we wrote the one-body particle and N-body particle fluid equations for the electron–positron fluid, taking into account the spin effects and regardless of the thermal effects. These equations are the first to be set for electron and positron fluids. The particle-antiparticle nature of the relativistic particles is explicit in this fluid theory. The nonrelativistic limit is shown to be in agreement with previous attempts to develop a spin plasma theory derived from the Pauli Hamiltonian. In the second step, we investigated the thermal effects without considering the spin effects and according to the enthalpy of the system. In the last step, we studied the electromagnetic mode propagation for this type of plasma and determined the range of wave transition.

The interaction potentials of charged particles with charged planes and axes in ionic crystals with the NaCl-type structure (in particular, in crystals of sodium, potassium, and rubidium halogenides) are calculated at a temperature of Т = 300 K. Moliere approximations are used in one-particle potentials of positively and negatively charged ions. Changes in the interaction-potential structures are also studied at elevated temperatures (for example, at 500 and 700 K) in the main and high-index directions. For relativistic electrons with Lorentz factors of γ = 50, 100 channeled along the principal charged (111) planes and also with a Lorentz factor of γ = 10 channeled along the principal charged [110] axes, the transverse energy levels and the wave functions corresponding to them are found numerically as a result of solving the corresponding Sturm—Liouville problems. For dispersionless electron beams moving at zero angles to the corresponding crystallographic planes and axes, in the dipole approximation, the spectra of spontaneous channeled radiation are calculated based on these data.

Most fast radio burst (FRB) models are built from comparatively common astronomical objects: neutron stars, black holes, and supernova remnants. Yet FRB sources are rare, and most of these objects, found in the Galaxy, do not make FRB. Special and rare circumstances may be required for these common objects to be sources of FRB. The recent discovery of a repeating FRB in a globular cluster belonging to the galaxy M81 suggests a model involving a neutron star and a close binary companion, likely a white dwarf; both neutron stars and close binaries are superabundant in globular clusters. Magnetic interaction is a plausible, though unproven, mechanism of acceleration of relativistic particles that may radiate coherently as FRB. In such a model, the energy source is the orbital kinetic energy, and not limited by the magnetostatic energy of a neutron star. Double neutron star binaries cannot be the observed long-lived repeating FRB sources, but might make much shorter lived sources, and perhaps non-repeating FRB.

The rotation powered pulsar loses angular momentum at a rate of the rotation power divided by the angular velocity $\Omega_*$. This means that the length of the lever arm of the angular momentum extracted by the photons, relativistic particles and wind must be on average $c/\Omega_*$, which is known as the light cylinder radius. Therefore, any deposition of the rotation power within the light cylinder causes insufficient loss of angular momentum. In this paper, we investigate two cases of this type of energy release: polar cap acceleration and Ohmic heating in the magnetospheric current inside the star. As for the first case, the outer magnetosphere beyond the light cylinder is found to compensate the insufficient loss of the angular momentum. We argue that the energy flux coming from the sub-rotating magnetic field lines must be larger than the solid-angle average value, and as a result, an enhanced energy flux emanating beyond the light cylinder is observed in different phases in the light curve from those of emission inside the light cylinder. As for the second case, the stellar surface rotates more slowly than the stellar interior. We find that the way the magnetospheric current closes inside the star is linked to how the angular momentum is transferred inside the star. We obtain numerical solutions which show that the magnetospheric current inside the star spreads over the polar cap magnetic flux embedded in the star in such a way that electromotive force is gained efficiently., Comment: Accepted for publication in MNRAS, 9 pages, 16 figures

The impact of an interplanetary shock significantly disturbs the Earth’s magnetosphere. Although the disturbances in the magnetotail induced by such an impact have extensively been investigated in previous studies, they are not still fully understood. In this study, we examined the disturbances produced in the central plasma sheet observed by the Cluster spacecraft. After the sudden impulse (SI) on the ground, significant compression of the magnetotail was observed. Initially, the dominant direction of the compression was the dawn-dusk direction, but later it changed to the north–south direction. Ions and electrons in the plasma sheet were significantly energized in the energy range from ~ 5 to ~ 100 keV. The energization was more effective on electrons than ions, and the energy dependence of the energization suggests that this process is non-adiabatic. We suggest that these particles can serve as the seed population of relativistic particles in the radiation belts.

The angular momentum of radiation related to the passage of relativistic particles in a cylindrical channel is studied theoretically. To enhance the angular momentum of radiation, it is proposed to place the channel in a strong magnetic field parallel to the channel axis. The trajectories of the particles in the channel, the conditions for trapping particles in the channeling mode are investigated and equations for calculating the orbital angular momentum of radiation are obtained. It is shown that the angular momentum of radiation of a uniform beam of particles in the channel is not equal to zero only if the particles enter the channel at an angle greater than the critical angle. A significant difference between vortex radiation from a bunch of cylindrical channels (for example bunch of carbon nanotubes) from laser or undulator radiation is that the radiation beam of the latter has only one vortex axis. While the radiation from the beam of cylindrical channels has one vortex axis per each channel. Dependence of the angular momentum of radiation on the value of magnetic field and on the incident angle is studied.

Publisher's version (útgefin grein), Interstellar probes and future interstellar travel will require relativistic rockets. The problem is that such a rocket drive requires that the rocket exhaust velocity from the fuel also is relativistic, since otherwise the rocket thrust is much too small: the total mass of the fuel will be so large that relativistic speeds cannot be reached in a reasonable time and the total mass of the rocket will be extremely large. Until now, no technology was known that would be able to give rocket exhaust at relativistic speed and a high enough momentum for relativistic travel. Here, a useful method for relativistic interstellar propulsion is described for the first time. This method gives exhaust at relativistic speeds and is a factor of at least one hundred better than normal fusion due to its increased energy output from the annihilation-like meson formation processes. It uses ordinary hydrogen as fuel so a return travel is possible after refuelling almost anywhere in space. The central nuclear processes have been studied in around 20 publications, which is considered to be sufficient evidence for the general properties. The nuclear processes give relativistic particles (kaons, pions and muons) by laser-induced annihilation-like processes in ultra-dense hydrogen H(0). The kinetic energy of the mesons is 1300 times larger than the energy of the laser pulse. This method is superior to the laser-sail method by several orders of magnitude and is suitable for large spaceships.

37. International Cosmic Ray Conference, ICRC 2021, Berlin, Germany, 15 Jul 2021 - 22 Jul 2021; Proceedings of Science 395, 1119 (2022). doi:10.22323/1.395.1119 special issue: "37th International Cosmic Ray Conference : ICRC2021 : 12-23 July 2021 : Berlin, Germany - Online / Editorial Board: Alexander Kappes, Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany ; Bianca Keilhauer, Karlsruhe Institute of Technology, Institute for Astroparticle Physics (IAP)", Published by SISSA, Trieste

This article extends the results of Arkeryd and Cercignani [6]. It is shown that the Cauchy problem for the relativistic Enskog equation in a periodic box has a global mild solution if the mass, energy and entropy of the initial data are finite. It is also found that the solutions of the relativistic Enskog equation weakly converge to the solutions of the relativistic Boltzmann equation in L1 if the diameter of the relativistic particle tends to zero.

We consider the quantum mechanical problem of the motion of a spinless charged relativistic particle with mass M, described by the Klein-Fock-Gordon equation with equal scalar Sr→ and vector Vr→ Coulomb plus ring-shaped potentials. It is shown that the system under consideration has both a discrete at EMc2 energy spectra. We find the analytical expressions for the corresponding complete wave functions. A dynamical symmetry group SU1,1 for the radial wave equation of motion is constructed. The algebra of generators of this group makes it possible to find energy spectra in a purely algebraic way. It is also shown that relativistic expressions for wave functions, energy spectra, and group generators in the limit c⟶∞ go over into the corresponding expressions for the nonrelativistic problem.

Astrophysical collisionless shocks are among the most powerful particle accelerators in the Universe. Generated by violent interactions of supersonic plasma flows with the interstellar medium, supernova remnant shocks are observed to amplify magnetic fields1 and accelerate electrons and protons to highly relativistic speeds2–4. In the well-established model of diffusive shock acceleration5, relativistic particles are accelerated by repeated shock crossings. However, this requires a separate mechanism that pre-accelerates particles to enable shock crossing. This is known as the ‘injection problem’, which is particularly relevant for electrons, and remains one of the most important puzzles in shock acceleration6. In most astrophysical shocks, the details of the shock structure cannot be directly resolved, making it challenging to identify the injection mechanism. Here we report results from laser-driven plasma flow experiments, and related simulations, that probe the formation of turbulent collisionless shocks in conditions relevant to young supernova remnants. We show that electrons can be effectively accelerated in a first-order Fermi process by small-scale turbulence produced within the shock transition to relativistic non-thermal energies, helping overcome the injection problem. Our observations provide new insight into electron injection at shocks and open the way for controlled laboratory studies of the physics underlying cosmic accelerators. In laser–plasma experiments complemented by simulations, electron acceleration is observed in turbulent collisionless shocks. This work clarifies the pre-acceleration to relativistic energies required for the onset of diffusive shock acceleration.

The electromagnetic angular momentum created by the convective fields of electrically charged relativistic particles in the immediate vicinity of the charges, where these fields exceed the fields of the purely electromagnetic radiation, is considered.

Fast radio bursts (FRBs) are bright, short-duration radio transients with very high brightness temperatures implying highly coherent emission. We suggest that the FRBs are caused by the self-focusing of an electron beam interacting with an ambient plasma right beyond the light cylinder radius of a neutron star. The magnetic field at the light cylinder radius is relatively high which can accommodate both young Crab-like systems and old millisecond pulsars addressing the diverse environments of FRBs. At the first stage, the intense pulsed-beam passing through the background plasma causes instabilities such that the trapped particles in local Buneman-type cavitons saturate the local field. The beam is then radially self-focused due to the circular electric field developed by the two-stream instability which leads to Weibel instability in the transverse direction. Finally, the non-linear saturation of the Weibel instability results in the self-modulational formation of solitons due to plasmoid instability. The resonant solitary waves are the breather-type solitons hosting relativistic particles with self-excited oscillations. The analytical solutions obtained for non-linear dispersion and solitons suggest that, near the current sheets, the relativistic bunches are accelerated/amplified by klystron-like structures due to self-excited oscillations by the induced local electric field. Boosted coherent radio emission propagates through a narrow cone with strong focusing due to radial electric field and magnetic pinching. The non-linear evolution of solitons and the stimulated emission are associated with the Buneman instability and the possibility of the presence of nanosecond shots in FRBs are investigated., Comment: MNRAS accepted

The paper is devoted to resonances playing an important role in direct and inverse scattering problems. A model of a relativistic particle on hybrid manifold consisting of a sphere with two semi-infinite wires attached is considered. The model is based on the theory of self-adjoint extensions of symmetric operators. Completeness of resonance states in the space of square integrable functions on the sphere is proved. The proof uses the relation between the completeness and the factorization of the characteristic function in Sz.-Nagy functional model. Keywords: Scattering, Resonance, Hybrid manifold, Dirac operator, MSC 2010: 47B38, 47E05

In this paper we prove the existence and multiplicity of subharmonic solutions for nonlinear equations involving the singular \begin{document}$ \phi $\end{document} -Laplacian. Such equations are in particular motivated by the one-dimensional mean curvature problems and by the acceleration of a relativistic particle of mass one at rest moving on a straight line. Our approach is based on phase-plane analysis and an application of the Poincare-Birkhoff twist theorem.

Ground-space interferometer RadioAstron provides unique opportunity to probe detail structure of the distant active galactic nuclei at μ as scales. Here we report on RadioAstron observations of the BL Lac object S5 0716 + 71, performed in a framework of the AGN Polarization and Survey Key Science Programs at 22 GHz during 2012–2018. We obtained the highest angular resolution image of the source to date, at 57 × 24 μ as. It reveals complex structure of the blazar jet in the inner 100 μ as, with emission regions that can be responsible for the blazar variability at timescales of a few days to week. Linear polarization is detected in the core and jet areas at the projected baselines up to about 5.6 Earth diameters. The observed core brightness temperature in the source frame of ⩾ 2.2 × 10 13 K is in excess of theoretical limits, suggesting the physical conditions are far from the equipartition between relativistic particles and magnetic field.

Motivated by the conduction properties of graphene discovered and studied in the last decades, we consider the quantum dynamics of a massless, charged, spin 1/2 relativistic particle in three dimensional space-time, in the presence of an electrostatic field in various configurations such as step or barrier potentials and generalizations of them. The field is taken as parallel to the y coordinate axis and vanishing outside of a band parallel to the x axis. The classical theory is reviewed, together with its canonical quantization leading to the Dirac equation for a 2-component spinor. Stationary solutions are numerically found for each of the field configurations considered, fromwhich we calculate the mean quantum trajectories of the particle and compare them with the corresponding classical trajectories, the latter showing a classical version of the Klein phenomenon. Transmission and reflection probabilities are also calculated, confirming the Klein phenomenon., Comment: 30 pages, 14 figures, Mathematica code annexed as an ancillary file. Version v2: Paragraph added in the introduction. Three new references. Version v3: Final version, publihshed in Eur. Phys. J

The multi-wavelength spectrum observed from M87 extends from radio wavelengths up to TeV gamma-ray energies. The radio through GeV components have been interpreted successfully using SSC models based on misaligned blazar jets, but the origin of the intense TeV emission detected during flares in 2004, 2005, and 2010 remains puzzling. It has been previously suggested that the TeV flares are produced when a relativistic proton jet originating in the core of M87 collides with a molecular cloud (or stellar atmosphere) located less than one parsec from the central black hole. We explore this scenario in detail here using a self-consistent model for the acceleration of relativistic protons in a shocked, two-fluid ADAF accretion disc. The relativistic protons accelerated in the disc escape to power the observed jet outflows. The distribution function for the jet protons is used to compute the TeV emission produced when the jet collides with a cloud or stellar atmosphere. The simulated broadband radiation spectrum includes radio, X-ray, and GeV components generated via synchrotron, as well as TeV emission generated via the production and decay of muons, positrons, and electrons. The self-consistency of the model is verified by computing the relativistic particle pressure using the distribution function, and comparing it with the relativistic particle pressure obtained from the hydrodynamical model. We demonstrate that the model is able to reproduce the multi-wavelength spectrum from M87 observed by VERITAS and HESS during the high-energy flares in 2004, 2005, and 2010., 27 pages, 9 figures

Several observations are revealing the widespread occurrence of mildly relativistic wide-angle AGN winds strongly interacting with the gas of their host galaxy. Such winds are potential cosmic-ray accelerators, as supported by gamma-ray observations of the nearby Seyfert galaxy NGC 1068 with the Fermi gamma-ray space telescope. The non-thermal emission produced by relativistic particles accelerated by the AGN-driven wind observed in the circum-nuclear molecular disk of such galaxy is invoked to produce the gamma-ray spectrum. The AGN wind model predicts a hard spectrum that extend in the very high energy band which differs significantly from those corresponding to other models discussed in the literature, like starburst or AGN jet. We present dedicated simulations of observations through the Cherenkov Telescope Array (CTA), the next-generation ground based gamma-ray observatory, of the very high energy spectrum of the Seyfert galaxy NGC 1068 assuming the AGN wind and the AGN jet models. We demonstrate that, considering 50 hours of observations, CTA can be effectively used to constrain the two different emission models, providing important insight into the physics governing the acceleration of particles in non-relativistic AGN-driven outflows. This analysis strongly motivates observations of Seyfert and starburst galaxies with CTA in order to test source population models of the extragalactic gamma-ray and neutrino backgrounds., 29 pages, 4 figures, accepted for publication in Astroparticle Physics

Relativistic quantum systems exhibit unique features not present at lower energies, such as the existence of both particles and antiparticles, and restrictions placed on the system dynamics due to the light cone. In order to understand what impact these relativistic phenomena have on the performance of quantum thermal machines we analyze a quantum Otto engine with a working medium of a relativistic particle in an oscillator potential evolving under Dirac or Klein-Gordon dynamics. We examine both the low-temperature, non-relativistic and high-temperature, relativistic limits of the dynamics and find that the relativistic engine operates with higher work output, but an effectively reduced compression ratio, leading to significantly smaller efficiency than its non-relativistic counterpart. Using the framework of endoreversible thermodynamics we determine the efficiency at maximum power of the relativistic engine, and find it to be equivalent to the Curzon-Ahlborn efficiency., 22 pages, 8 figures