Article
Astronomy & Astrophysics
Olivier Deligny
Summary: This paper investigates the diffusion process of charged particles in a purely turbulent magnetic field, using a red-noise approximation to model the correlation function of the magnetic field. The study shows the resonance between the Larmor radius of particles and the wavelength power spectrum of turbulence, extending previous results. The findings are consistent with those obtained using a Monte Carlo generator.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Siyao Xu, Alex Lazarian
Summary: In this study, we investigate shock acceleration in a realistic astrophysical environment and find that the turbulent dynamo amplifies both upstream and downstream magnetic fields, which introduces variations of shock obliquities, enables energy gain, leads to various spectral indices of accelerated particles, regulates the diffusion of particles, and increases the shock acceleration efficiency. Our results demonstrate that the condition of the ambient interstellar environment plays an important role in shock acceleration.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Berndt Mueller, Di-Lun Yang
Summary: This study explores the important yet often overlooked role of gluons in spin transport, particularly in quark gluon plasmas, and its connection to local parity violation. By applying the formalism of quantum kinetic theory to weakly coupled quantum chromodynamics, the source terms for quark spin polarization are derived. These source terms involve parity-odd correlators of dynamically generated color fields in near-equilibrium quark gluon plasmas, resulting in locally fluctuating axial charge currents. The results provide a possible explanation for the spin alignment of vector mesons measured in high-energy nuclear collisions.
Article
Astronomy & Astrophysics
Siyao Xu, Hui Li
Summary: We investigate the role of MHD turbulence measured by Voyager in the VLISM in modeling the Interstellar Boundary Explorer ribbon. We find that the mirroring effect of compressible modes of MHD turbulence dominates over that of the mean magnetic field. By studying the new mirror diffusion mechanism, we demonstrate that mirror diffusion can confine pickup ions and preserve their initial pitch angles, which contributes to the enhanced intensity of energetic neutral atoms returning to the heliosphere. The ribbon width is determined by the range of effective turbulent mirroring and the field line wandering induced by Alfvenic modes.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Eduardo Guendelman, Ramon Herrera, David Benisty
Summary: This paper discusses a unified multiscalar field model with three flat regions, which can describe the evolution of the universe during the inflation, early, and late dark energy epochs. By studying the couplings between scalar fields and measures, the potential and perturbations of the model are obtained, providing insights into the evolution and properties of the universe.
Article
Astronomy & Astrophysics
K. Ehlert, R. Weinberger, C. Pfrommer, V Springel
Summary: The study explores the relationship between velocity fields and magnetic fields in galaxy clusters through simulations, finding that jet outbursts have only a local impact on the velocity field with increased dispersion hidden by pre-existing turbulence. The projected velocity distributions show complex structures, posing challenges for observational interpretation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Review
Astronomy & Astrophysics
Alex Lazarian, Siyao Xu, Yue Hu
Summary: This review focuses on the propagation of cosmic rays in turbulent and magnetized astrophysical media, addressing the problems of perpendicular and parallel diffusion and discussing recent theoretical findings and possible solutions.
FRONTIERS IN ASTRONOMY AND SPACE SCIENCES
(2023)
Article
Chemistry, Multidisciplinary
Sina Mayr, Lukas Flajsman, Simone Finizio, Ales Hrabec, Markus Weigand, Johannes Forster, Hermann Stoll, Laura J. Heyderman, Michal Urbanek, Sebastian Wintz, Jorg Raabe
Summary: The influence of a static in-plane magnetic field on the emission of nanoscale spin waves from magnetic vortex cores is studied in disk structures of synthetic ferrimagnets and single ferromagnetic layers. Increasing magnetic bias field displaces the wave-emitting vortex core from the center of the disk toward its edge without altering the spin-wave dispersion relation noticeably. At higher magnetic fields, anisotropic lateral expansion of the core occurs in single-layer disks leading to directional emission and propagation of waves.
Article
Astronomy & Astrophysics
Mustafa A. Amin, Zong-Gang Mou
Summary: The study focuses on investigating the bursts of electromagnetic and scalar radiation resulting from the collision and merger of oscillons made from axion-like particles. It is found that radiation becomes the dominant source of energy loss after the merger under resonance condition. The backreaction of scalar and electromagnetic radiation is also included in the simulations, providing insights into the time and energy scales involved in the process.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Mechanics
A. Guemes, S. Discetti, A. Ianiro, B. Sirmacek, H. Azizpour, R. Vinuesa
Summary: This study evaluates the applicability of super-resolution generative adversarial networks (SRGANs) for reconstructing turbulent flow quantities, demonstrating that SRGAN can enhance the resolution of coarse wall measurements and provide better instant reconstructions. Despite challenges with lower resolution inputs, SRGAN yields very good reconstruction results, capturing large-scale flow structures effectively.
Article
Mechanics
Pieter Bauweraerts, Johan Meyers
Summary: By utilizing large-eddy simulations (LES) and a four-dimensional variational data assimilation algorithm, we investigate the reconstruction of a turbulent flow field in the atmospheric boundary layer from a time series of lidar measurements. The study shows that LES outperforms the Taylor's frozen turbulence (TFT) model in the reconstruction process under different lidar scanning modes.
JOURNAL OF FLUID MECHANICS
(2021)
Review
Astronomy & Astrophysics
Denis Wittor
Summary: The discovery of diffuse radio emission in galaxy clusters confirms the presence of energetic cosmic-ray electrons and cosmic magnetic fields in the Universe. Recent detection of diffuse radio emission in intercluster bridges strengthens the theory that cosmic magnetic fields and cosmic-ray electrons exist on large scales. Radio observations are crucial for studying these phenomena.
Article
Astronomy & Astrophysics
D. Paoletti, J. Chluba, F. Finelli, J. A. Rubino-Martin
Summary: We update and extend the constraints on primordial magnetic fields in the cosmic microwave background through the dissipation effects of ambipolar diffusion and magnetohydrodynamic decaying turbulence. Using the latest data release and map making algorithm, our study achieves tighter constraints on the magnetic field amplitudes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Fei Qin, David Parkinson, Sungwook E. Hong, Cristiano G. Sabiu
Summary: The distribution of matter can teach us about dark matter, dark energy, and gravity. To understand the Universe's matter, we rebuild the density and velocity fields from galaxies. Using simulated halos as proxies for galaxies, a convolutional neural network, V-net, is used to reconstruct the fields. The V-net provides better fits to the density field and improved predictions for velocity amplitudes, but reduces the precision of the estimated β parameter.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Clara Dehman, Daniele Vigano, Stefano Ascenzi, Jose A. Pons, Nanda Rea
Summary: We perform 3D fully coupled magneto-thermal simulations of neutron stars with complex initial magnetic field topology. The surface dipolar component does not increase over time, contradicting the observed properties of young pulsars and magnetars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
