Numerical heating in particle-in-cell (PIC) codes currently precludes the accurate simulation of cold, relativistic plasma over long periods, severely limiting their applications astrophysical environments. We present a spatially higher-order PIC algorithm one spatial dimension, which conserves charge and momentum exactly. utilize smoothness implied by usage interpolation functions to achieve (up fifth order). validate our against several test problems -- thermal stability stationary plasma,...

The particle-in-cell (PIC) method is successfully used to study magnetized plasmas. However, this requires large computational costs and limits simulations short physical run times often set-ups of less than three spatial dimensions. Traditionally, circumvented either via hybrid-PIC methods (adopting massless electrons) or magneto-hydrodynamic-PIC (modelling the background plasma as a single charge-neutral magneto-hydrodynamical fluid). Because both preclude modelling important...

Abstract Cosmic-ray (CR) feedback is critical for galaxy formation as CRs drive galactic winds, regularize star in galaxies, and escape from active nuclei to heat the cooling cores of clusters. The strength depends on their coupling background plasma and, such, effective CR transport speed. Traditionally, this has been hypothesized depend balance between wave growth CR-driven instabilities damping. Here, we study physics first principles, starting a gyrotropic distribution ions that stream...

Thermal electrons cannot directly participate in the process of diffusive acceleration at electron-ion shocks because their Larmor radii are smaller than shock transition width: this is well-known electron injection problem acceleration. Instead, an efficient pre-acceleration must exist that scatters off electromagnetic fluctuations on scales much shorter ion gyro radius. The recently found intermediate-scale instability provides a natural way to produce such parallel shocks. drives comoving...

The annihilation of TeV photons from extragalactic sources and the background light produces ultrarelativistic $e^{\pm}$ beams, which are subject to powerful plasma instabilities that sap their kinetic energy. Here we study linear phase these pair beams drive. To this end, calculate growth rate beam oblique instability in electrostatic approximation both reactive regimes, assuming a Maxwell-J{\"u}ttner distribution for beam. We reproduce well-known rates mode. demonstrate there is broad...

Abstract Cosmic-ray-driven (CR-driven) instabilities play a decisive role during particle acceleration at shocks and CR propagation in galaxies galaxy clusters. These amplify magnetic fields modulate transport so that the intrinsically collisionless population is tightly coupled to thermal plasma provides dynamical feedback. Here, we show CRs with finite pitch angle drive electromagnetic waves (along background field) unstable on intermediate scales between gyroradii of ions electrons as...

Very high energy gamma-rays from extragalactic sources produce pairs the background light, yielding an electron–positron pair beam. This beam is unstable to various plasma instabilities, especially "oblique" instability, which can be dominant cooling mechanism for However, recently, it has been claimed that nonlinear Landau damping renders physically irrelevant by reducing effective rate a low level. Here we show with numerical calculations 8 × 10−4 growth of linear sufficient instability...

Abstract An intergalactic magnetic field (IGMF) stronger than 3 × 10 −13 G would explain the lack of a bright, extended degree-scale, GeV-energy inverse Compton component in gamma-ray spectra TeV blazars. A robustly predicted consequence presence such is existence degree-scale halos (gamma-ray bow ties) about TeV-bright active galactic nuclei, corresponding to more half all radio galaxies. However, emitting regions these are confined and aligned with direction relativistic jets associated...

TeV-blazars potentially heat the intergalactic medium (IGM) as their gamma rays interact with photons of extragalactic background light to produce electron-positron pairs, which lose kinetic energy surrounding through plasma instabilities. This results in a heating mechanism that is only weakly sensitive local density, and therefore approximately spatially uniform, naturally producing an inverted temperature-density relation underdense regions. In this paper we go beyond approximation...

We study the underlying physics of cosmic ray (CR)-driven instabilities that play a crucial role for CR transport across wide range scales, from interstellar to galaxy cluster environments. By examining linear dispersion relation CR-driven in magnetised electron–ion background plasma, we establish both intermediate and gyroscale have resonant origin, show these resonances can be understood via simple graphical interpretation. These destabilise wave modes parallel large-scale magnetic field...

Abstract Many astrophysical plasmas are prone to beam-plasma instabilities. For relativistic and dilute beams, the spectral support of instabilities is narrow, i.e., linearly unstable modes that grow with rates comparable maximum growth rate occupy a narrow range wavenumbers. This places stringent requirements on box-sizes when simulating evolution We identify implied lower limits box size imposed by longitudinal beam plasma instability, typically most condition required correctly capture...

Abstract We explore how inhomogeneity in the background plasma number density alters growth of electrostatic unstable wavemodes beam–plasma systems. This is particularly interesting for blazar-driven instabilities, which may be suppressed by inhomogeneities intergalactic medium (IGM) as was recently claimed literature. Using high-resolution particle-in-cell simulations with SHARP code, we show that instability local, i.e., regions almost homogeneous will support Langmuir waves even when they...

ABSTRACT Extended inverse Compton halos are generally anticipated around extragalactic sources of gamma rays with energies above 100 GeV. These result from scattered cosmic microwave background photons by a population high-energy electron/positron pairs produced the annihilation on infrared background. Despite observed attenuation rays, halo emission has yet to be directly detected. Here, we demonstrate that in most cases these expected highly anisotropic, distributing upscattered along axes...

Pair creation on the cosmic infrared background and subsequent inverse-Compton scattering CMB potentially reprocesses TeV emission of blazars into faint GeV halos with structures sensitive to intergalactic magnetic fields (IGMF). Previous work has shown that these are then highly-anisotropic extended. If coherence length IGMF is greater than cooling pairs, orientation gamma-ray halo will be correlated direction field which unknown expected change for each source. In order constructively add...

Abstract Many-degree-scale gamma-ray halos are expected to surround extragalactic high-energy sources. These arise from the inverse Compton emission of an intergalactic population relativistic electron/positron pairs generated by annihilation <?CDATA $\gtrsim 100\,\mathrm{GeV}$?> gamma rays on background light. typically anisotropic due jetted structure which they originate (in case radio galaxies) or oriented perpendicular a large-scale magnetic field (for blazar geometries). Here, we...

We study the longitudinal stability of beam–plasma systems in presence a density inhomogeneity background plasma. Previous works have focused on non-relativistic regime where hydrodynamical models are used to evolve pre-existing Langmuir waves within inhomogeneous plasmas. Here, for first time we problem with kinetic equations fully relativistic way. do not assume existence waves, and focus rate mechanism by which excited such from an initial perturbation. derive structure unstable modes...

Cosmic ray (CR) feedback is critical for galaxy formation as CRs drive galactic winds, regularize star in galaxies, and escape from active nuclei to heat the cooling cores of clusters. The strength depends on their coupling background plasma and, such, effective CR transport speed. Traditionally, this has been hypothesized depend balance between wave growth CR-driven instabilities damping. Here, we study physics first principles, starting a gyrotropic distribution ions that stream along...

Energy dissipation in collisionless shocks is a key mechanism various astrophysical environments. Its non-linear nature complicates analytical understanding and necessitate Particle-in-Cell (PIC) simulations. This study examines the impact of reducing ion-to-electron mass ratio ($m_r$), to decrease computational cost, on energy partitioning 1D3V (one spatial three velocity-space dimensions) PIC simulations strong, non-relativistic, parallel electron-ion using SHARP code. We compare with...

Abstract Energy dissipation in collisionless shocks is a key mechanism various astrophysical environments. Its nonlinear nature complicates analytical understanding and necessitates particle-in-cell (PIC) simulations. This study examines the impact of reducing ion-to-electron mass ratio ( m r ), to decrease computational cost, on energy partitioning one spatial three velocity-space dimension PIC simulations strong, nonrelativistic, parallel electron–ion using SHARP code. We compare with...

The particle-in-cell (PIC) method is successfully used to study magnetized plasmas. However, this requires large computational costs and limits simulations short physical run-times often setups in less than three spatial dimensions. Traditionally, circumvented either via hybrid-PIC methods (adopting massless electrons) or magneto-hydrodynamic-PIC (modelling the background plasma as a single charge-neutral magneto-hydrodynamical fluid). Because both preclude modelling important plasma-kinetic...

We study the underlying physics of cosmic-ray (CR) driven instabilities that play a crucial role for CR transport across wide range scales, from interstellar to galaxy cluster environments. By examining linear dispersion relation CR-driven in magnetised electron-ion background plasma, we establish both, intermediate and gyroscale have resonant origin show these resonances can be understood via simple graphical interpretation. These destabilise wave modes parallel large-scale magnetic field...

ABSTRACT The intergalactic medium (IGM) acts like a calorimeter recording energy injection by cosmic structure formation, shocks and photoheating from stars active galactic nuclei. It was recently proposed that spatially inhomogeneous TeV-blazars could significantly heat up the underdense IGM, resulting in patches of both cold warm IGM around z ≃ 2−3. goal this study is to compare predictions different blazar heating models with recent observations IGM. We perform set cosmological...

We discuss a model for universe with discrete matter content instead of the continuous perfect fluid taken in FRW models. show how redshift such deviates from corresponding one an cosmology. This illustrates fact that averaging and then evolving it time, is not same as content. The main reason deviation photons mainly travel empty space rather than geometry.