Article
Astronomy & Astrophysics
Jennifer Schober, Igor Rogachevskii, Axel Brandenburg
Summary: The dynamics of magnetic fields in chiral magnetohydrodynamics are studied. It is found that a small-scale chiral dynamo can occur if fluctuations of the chiral chemical potential are correlated on large length scales. The generated magnetic field grows exponentially until the nonlinear backreaction sets in and the dynamo saturates.
Article
Astronomy & Astrophysics
N. S. Dzhalilov, R. Ismayilli
Summary: The linear magnetohydrodynamic Kelvin-Helmholtz instability in an anisotropic plasma is investigated using the governing equations derived from the 16 moments of Boltzmann-Vlasov kinetic equations. The study finds that quasi-transverse modes grow faster in the case of tangential discontinuity between supersonic flows along the magnetic field. Dispersion equations for these modes considering the finite width of the transition zone are derived. Analytical solutions are obtained, which aid in verifying numerical simulations. In addition, the study shows that the fundamental plasma instabilities arising from the transition zone's finite width can modify and enhance the Kelvin-Helmholtz instability.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Andrew Hillier, Ben Snow, Inigo Arregui
Summary: In many astrophysical systems, the mixing between cool and hot temperature gas/plasma creates an intermediate temperature phase with increased radiative losses, driving efficient cooling. This paper derives equations to model the evolution of this mixing layer, and predicts the cooling rate and the rate of condensation of coronal material due to mixing. These predictions are compared to simulations and applied to prominence threads and spicules, showing that the mixing process can explain the warm emission observed without the need for additional heating.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
G. Guzzi, A. Settino, F. Valentini, F. Malara
Summary: This work aims to derive explicit forms for stationary configurations of magnetized plasmas with planar shearing flows within the hybrid Vlasov-Maxwell description. Two configurations were considered: one with a uniform magnetic field obliquely directed with respect to the bulk velocity and the second with a uniform-magnitude variable-direction magnetic field.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Multidisciplinary Sciences
Ge Liu, Bin Chen
Summary: In this study, the pressure signal of oil pulsating flow was decomposed using VMD, with the proposed center frequency slope criterion and energy value method successfully separating the signal into 9 components and identifying the beat vibration characteristics. The main components of the pressure signal were determined based on correlation and energy calculation, showing frequencies at multiples of the system spindle rotation frequency and exhibiting beat vibration properties.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Multidisciplinary
P. Helander, G. G. Plunk
Summary: Rigorous upper bounds on the growth rate of local gyrokinetic instabilities in magnetized plasmas are derived from the evolution equation for the Helmholtz free energy. These bounds apply to both electrostatic and electromagnetic instabilities, regardless of the number of particle species, their collision frequency, and the geometry of the magnetic field. These bounds not only apply to linear instabilities, but also set an upper limit on the nonlinear growth of the free energy.
PHYSICAL REVIEW LETTERS
(2021)
Article
Mechanics
M. Tsoy, S. Skripkin, I. Litvinov
Summary: Two different scenarios of spiral vortex breakdown are experimentally observed and numerically investigated in a swirl flow into a conical diffuser. The primary spiral vortex breakdown occurs near the inlet of the conical diffuser when the cone angle beta is greater than 3 degrees. The secondary spiral vortex breakdown occurs at the exit of the cone when beta is less than or equal to 3 degrees. Additionally, the coexistence of two spiral vortices is observed, and their reasons are visualized and explained for the first time.
Article
Mathematics, Applied
Alvaro G. Lopez, Rustam Ali, Laxmikanta Mandi, Prasanta Chatterjee
Summary: The study presents a hydrodynamic model of a quantum dusty plasma and mathematically proves the conservatism of the resulting dust ion-acoustic plasma waves. The property is further confirmed numerically and chaotic dynamics are explored using Lyapunov characteristic exponents. The research shows the existence of chaotic dynamics for a wide range of parameter values and illustrates how they organize in the parameter space with continuously varying initial conditions.
Article
Astronomy & Astrophysics
Loren E. Held, Henrik N. Latter
Summary: The study reveals through numerical simulations that turbulent stress oscillations can lag behind pressure oscillations by approximately 5 orbits in certain cases, with implications for understanding thermal and viscous overstability in discs around compact objects.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jinsong Zhao, Louchuang Lee, Huasheng Xie, Yuhang Yao, Dejin Wu, Yuriy Voitenko, Viviane Pierrard
Summary: This study proposes a systematic method to quantify linear wave-particle interactions based on the Vlasov-Maxwellian model. The physical mechanisms responsible for the damping of the Alfven-mode wave in wavevector space are clarified. Evident signatures of wave-particle interactions between Alfven-mode waves and resonant/nonresonant particles in the velocity space are exhibited for the first time.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Masanori Iwamoto, Emanuele Sobacchi, Lorenzo Sironi
Summary: In this paper, the filamentation instability (FI) in unmagnetized pair plasmas is studied using fully kinetic particle-in-cell simulations. The results show that the FI generates transverse density filaments, and the electromagnetic wave propagates in near vacuum between them, resembling a waveguide. The density filaments continue to merge until force balance is established between the wave ponderomotive force and the plasma pressure gradient. The merging time-scale is estimated and the implications for FRB observations are discussed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Seong-Yeop Jeong, Clare Watt
Summary: The wave instability plays a vital role in redistributing energy and momentum in astrophysical plasmas. Understanding the wave energy density and growth rate is crucial for analyzing different wave instabilities in plasma regimes. In this study, we derived analytic expressions for the energy density and growth rate of resonant waves with arbitrary propagation angles in relativistic plasmas. Our results contribute to a better understanding of wave instability and have the potential to be combined with quasi-linear theory for studying the time evolution of particle momentum distribution and resonant wave properties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Che, A. O. Benz, G. P. Zank
Summary: This study investigates the ion beam-driven instabilities in a low beta collisionless space plasma using particle-in-cell (PIC) simulations. It is found that both the Buneman instability and the resonant electromagnetic (EM) right-handed (RH) ion beam instability can be driven when the ion beam drift exceeds the theoretical thresholds. The Buneman instability dissipates only a small fraction of the kinetic energy of the ion beam and causes significant electron heating. However, the ion beam-driven Buneman instability is effectively quenched by the resonant EM RH ion beam instability. The resonant EM RH ion beam instability dominates when the ion drift velocity is larger than the Alfven speed, leading to the generation of RH Alfven waves and RH whistler waves. The intensity of Alfven waves decreases with a decrease in ion beam drift velocity, while the intensity of whistler waves increases.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Saee Dhawalikar, Christoph Federrath, Seth Davidovits, Romain Teyssier, Sabrina R. Nagel, Bruce A. Remington, David C. Collins
Summary: In this study, hydrodynamical simulations are used to investigate shock-induced turbulence, and the turbulence driving parameter is measured by analyzing the density and velocity distributions. The results show that shock-driven turbulence is consistent with strongly compressive driving.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Eonho Chang, Pascale Garaud
Summary: Zahn's model for turbulent mixing induced by rotational shear has been validated in non-rotating shear flows, but its validity in the presence of rotation is unclear. New instabilities in rotating fluids, such as the Goldreich-Schubert-Fricke instability, have been studied, with the finding that either the GSF or shear instability tends to dominate the system. It is challenging to predict which instability 'wins' for given input parameters, as the diffusive shear instability is subcritical and requires a 'primer' to seed it.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Physics, Nuclear
Mark Mace, Niklas Mueller, Soeren Schlichting, Sayantan Sharma
Summary: The transfer of chirality between fermions and gauge fields is crucial for understanding anomalous transport phenomena. Studies have shown that chirality imbalance in the fermion sector triggers chiral plasma instabilities in the gauge field sector, leading to the generation of long-range helical magnetic fields through a self-similar turbulent cascade of magnetic helicity.
Article
Physics, Nuclear
Niklas Mueller, Andrey Tarasov, Raju Venugopalan
Summary: This talk explores using a hybrid quantum computer to overcome limitations of classical computers in studying nuclear structure functions in the high energy Regge limit of QCD. By expressing the fermion determinant in the QCD path integral as a quantum mechanical path integral over world-lines, computations can be performed using few qubits and shallow circuits in the NISQ era, with potential for scalability and extension to other real-time correlation functions in QCD.
Article
Astronomy & Astrophysics
K. Boguslavski, T. Lappi, M. Mace, S. Schlichting
Summary: We have developed a non-perturbative method to obtain fermion spectral functions in a non-Abelian gauge theory with high occupation numbers. By applying this method, we extracted the spectral function of fermions in a highly occupied non-Abelian plasma near its non-thermal fixed point. The results show good agreement with hard loop perturbation theory and provide insights into the momentum dependence of the damping rate of collective excitations.
Article
Physics, Multidisciplinary
Niklas Mueller, Torsten Zache, Robert Ott
Summary: This article studies the entanglement structure and thermalization process of Z(2) lattice gauge theory. By using dual theories and nonequilibrium dynamics, the authors identify a characteristic sequence.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Particles & Fields
Dominik Schweitzer, Soeren Schlichting, Lorenz von Smekal
Summary: We study the dynamics of self-interacting scalar fields with Z2 symmetry near a critical point. We calculate the spectral functions of the order parameter and observe that they maintain their Breit-Wigner shape with non-trivial power-law dispersion at the critical point. We determine characteristic time scales and the dynamic critical exponent z, confirming the existence of dynamic scaling.
Article
Physics, Nuclear
Maurice Coquet, Xiaojian Du, Jean-Yves Ollitrault, Soeren Schlichting, Michael Winn
Summary: This study investigates the effect of the transverse mass Mt on the spectrum of dileptons produced by the quark-gluon plasma. The violations of Mt scaling are evaluated as a function of the shear viscosity to entropy ratio (eta/s) that controls the equilibration time. The research also determines the dependence of the spectrum on system size, centrality, rapidity, and collision energy.
Article
Physics, Multidisciplinary
Victor E. Ambrus, S. Schlichting, C. Werthmann
Summary: We simulate the space-time dynamics of high-energy collisions using a microscopic kinetic description and find that hydrodynamics provides an accurate description of collective flow in certain conditions. Our findings have implications for the applicability of hydrodynamics in different types of collisions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Astronomy & Astrophysics
Xiaojian Du, Stephan Ochsenfeld, Soeren Schlichting
Summary: This article studies the response of the energy-momentum tensor in various kinetic theories, ranging from the simple relaxation time approximation to Quantum Chromodynamics. Regardless of the differences in microscopic properties, there is a remarkable universality in the response functions from conformal theories. The response to scalar perturbations in kinetic theory can be effectively described by a pair of one hydrodynamic sound mode and one non-hydrodynamic mode. Even beyond the range of validity of hydrodynamics, the energy-momentum response in position space can be effectively described by one single mode with a non-trivial dispersion relation and residue.
Article
Astronomy & Astrophysics
Victor E. Ambrus, S. Schlichting, C. Werthmann
Summary: This study focuses on evaluating the dependence of collective flow on the full opacity in high-energy heavy-ion collisions using a microscopic kinetic description. By comparing kinetic theory calculations to hydrodynamic and hybrid simulations for an average initial state, the shortcomings and inaccuracies of hydrodynamic models are identified, and modified simulation setups are presented for improvement.
Article
Astronomy & Astrophysics
S. Demirci, T. Lappi, S. Schlichting
Summary: By calculating cross sections with fluctuating color charges Gaussian hot spots, we find that the existence of gluonic hot spots inside the proton affects the production cross sections, which are sensitive to the size of the target, the structure of the probe, and the transverse momentum transfer (t).
Article
Astronomy & Astrophysics
Xiaojian Du, Michal P. Heller, Soeren Schlichting, Viktor Svensson
Summary: We use principal component analysis to study the hydrodynamic attractor in Yang-Mills kinetic theory undergoing the Bjorken expansion with color glass condensate initial conditions. The late-time hydrodynamic attractor is characterized by a single principal component determining the overall energy scale. The approach to the hydrodynamic attractor at late times is well described by an exponential, which is dependent on the coupling and the shear viscosity to entropy density ratio.
Article
Astronomy & Astrophysics
B. Schenke, S. Schlichting, P. Singh
Summary: This study investigates the effects of event geometry and initial state correlations on collective phenomena in high-multiplicity collisions in small systems. The research finds that event geometry is correlated across large rapidity intervals, while initial state momentum correlations are relatively short-range in rapidity.
Article
Astronomy & Astrophysics
Soren Schlichting, Ismail Soudi
Summary: We study the momentum broadening kernel in high-temperature QCD plasmas using a recent nonperturbative determination and compare it with perturbative determinations and various approximations in the literature.
Article
Astronomy & Astrophysics
Victor E. Ambrus, S. Schlichting, C. Werthmann
Summary: We employ an effective kinetic description to study the space-time dynamics and development of transverse flow in small and large collision systems. We find that even in the limit of very large opacities, deviations between kinetic theory and hydrodynamics persist, which can be attributed to the early preequilibrium phase.
Article
Astronomy & Astrophysics
Andreas Ipp, David Mueller, Soeren Schlichting, Pragya Singh
Summary: This study performs an analytic calculation of color fields in heavy-ion collisions by considering the collision of longitudinally extended nuclei in the dilute limit of the color glass condensate effective field theory of high-energy QCD. The rapidity profile of the transverse pressure is evaluated within a simple specific model of nuclear collision geometry and compared to (3 + 1)D classical Yang-Mills simulations, showing a correlation between the results.
