A5086116818- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Geomagnetism and Paleomagnetism Studies
- Astrophysical Phenomena and Observations
- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Seismic Imaging and Inversion Techniques
- Atmospheric Ozone and Climate
- Reservoir Engineering and Simulation Methods
- Fluid Dynamics and Turbulent Flows
- Black Holes and Theoretical Physics
- Combustion and Detonation Processes
- Quantum Chromodynamics and Particle Interactions
- Scientific Research and Discoveries
- Seismic Waves and Analysis
- Radio Astronomy Observations and Technology
- Underwater Acoustics Research
Hanzhong Central Hospital
2023-2025
Florida Museum of Natural History
2023-2024
University of Florida
2023-2024
Institute for Advanced Study
2020-2023
Princeton Public Schools
2023
Sichuan Agricultural University
2022
Johns Hopkins University
2020
Los Alamos National Laboratory
2020
University of Wisconsin–Madison
2016-2020
Sun Yat-sen University
2019
The Probe of Inflation and Cosmic Origins (PICO) is a proposed probe-scale space mission consisting an imaging polarimeter operating in frequency bands between 20 800 GHz. We describe the science achievable by PICO, which has sensitivity equivalent to more than 3300 Planck missions, technical implementation, schedule cost.
ABSTRACT Starburst galaxies are efficient γ-ray producers, because their high supernova rates generate copious cosmic ray (CR) protons, and gas densities act as thick targets off which these protons can produce neutral pions thence γ-rays. In this paper, we present a first-principles calculation of the mechanisms by CRs propagate through such environments, combining astrochemical models with analysis turbulence in weakly ionized plasma. We show that cannot scatter strong large-scale found...
By following the Kazantsev theory and taking into account both microscopic turbulent diffusion of magnetic fields, we develop a unified treatment kinematic nonlinear stages dynamo, study dynamo process for full range Prandtl number Pm ionization fractions. We find striking similarity between dependence behavior on in conducting fluid R (a function fraction) partially ionized gas. In weakly medium, stage is largely extended, including not only exponential growth but new regime characterized...
Magnetic reconnection, topological change in magnetic fields, is a fundamental process magnetized plasmas. It associated with energy release regions of field annihilation, but this only one facet process. Astrophysical flows normally have very large Reynolds numbers and are expected to be turbulent, agreement observations. In strong turbulence lines constantly reconnect everywhere at all scales, making reconnection an intrinsic part turbulent cascade. We note that inconsistent the usual...
Abstract As the fundamental physical process with many astrophysical implications, diffusion of cosmic rays (CRs) is determined by their interaction magnetohydrodynamic (MHD) turbulence. We consider magnetic mirroring effect arising from MHD turbulence on CRs. Due to intrinsic superdiffusion turbulent fields, CRs large pitch angles that undergo mirror reflection, i.e., bouncing CRs, are not trapped between mirrors, but move diffusively along field, leading a new type parallel diffusion,...
ABSTRACT Owing to the complexity of turbulent magnetic fields, modelling diffusion cosmic rays is challenging. Based on current understanding anisotropic magnetohydrodynamic (MHD) turbulence, we use test particles examine rays’ superdiffusion in direction perpendicular mean field. By changing Alfvén Mach number MA and sonic MS compressible MHD simulations, our study covers a wide range astrophysical conditions including subsonic warm gas phase supersonic cold molecular gas. We show that...
ABSTRACT Recently, some fast radio burst (FRB) repeaters were reported to exhibit complex, diverse variations of Faraday rotation measures (RMs), which implies that they are surrounded by an inhomogeneous, dynamically evolving, magnetized environment. We systematically investigate possible astrophysical processes may cause RM FRB repeater. The include (1) a supernova remnant (SNR) with fluctuating medium; (2) binary system stellar winds from massive/giant star companion or flares low-mass...
Observations reveal a uniform Kolmogorov turbulence throughout the diffuse ionized interstellar medium (ISM) and supersonic preferentially located in Galactic plane. Correspondingly, we consider distribution of electron density fluctuations consisting not only spectrum but also short-wave-dominated with structure formed at small scales due to shocks. The resulting dependence scatter broadening time on dispersion measure (DM) naturally interprets existing observational data for both low...
The Probe of Inflation and Cosmic Origins (PICO) is an imaging polarimeter that will scan the sky for 5 years in 21 frequency bands spread between 799 GHz. It produce full-sky surveys intensity polarization with a final combined-map noise level 0.87 $\mu$K arcmin required specifications, equivalent to 3300 Planck missions, our current best-estimate would have 0.61 (6400 missions). PICO either determine energy scale inflation by detecting tensor scalar ratio at $r=5\times 10^{-4}~(5\sigma)$,...
Fast radio bursts (FRBs) have been identified as extragalactic sources which can make a probe of turbulence in the intergalactic medium (IGM) and their host galaxies. To account for observed millisecond pulses caused by scatter broadening, we examine variety possible models electron density fluctuations both IGM galaxy medium. We find that short-wave-dominated power-law spectrum density, may arise highly supersonic with pronounced local dense structures shock-compressed gas interstellar...
Abstract As a fundamental astrophysical process, the scattering of particles by turbulent magnetic fields has its physical foundation laid magnetohydrodynamic (MHD) turbulence theory. In framework modern theory MHD turbulence, we derive generalized broadened resonance function taking into account both fluctuations and nonlinear decorrelation arising in specify energy range for dominance different broadening mechanisms. The allows beyond threshold linear resonance. By analytically determining...
ABSTRACT We study the damping processes of both incompressible and compressible magnetohydrodynamic (MHD) turbulence in a partially ionized medium. start from linear analysis MHD waves, applying single-fluid two-fluid treatments. The rates derived are then used determining scales turbulence. physical connection between scale cutoff boundary waves is investigated. find two branches slow modes propagating ions neutrals, respectively, below turbulence, offer thorough discussion their...
Abstract Stars form in molecular clouds the interstellar medium (ISM) with a turbulent kinematic state. Newborn stars therefore should retain kinematics of their natal clouds. Gaia DR2 and APOGEE-2 surveys combination provide three-dimensional (3D) positions 3D velocities young Orion Molecular Cloud Complex. Using full 6D measurements, we compute velocity structure functions (VSFs) six different groups within We find that motions all diffuse exhibit strong characteristics turbulence. Their...
The interstellar medium (ISM) is turbulent on all scales and in phases. In this paper, we study turbulence with different tracers four nearby star-forming regions: Orion, Ophiuchus, Perseus, Taurus. We combine the APOGEE-2 Gaia surveys to obtain full 6-dimensional measurements of positions velocities young stars these regions. velocity structure functions (VSFs) show a universal scaling turbulence. also H{\alpha} gas kinematics regions from Wisconsin H-Alpha Mapper. VSFs are more diverse...
Abstract Magnetic fields of the order 100 μ G observed in young supernova remnants cannot be amplified by shock compression alone. To investigate amplification caused a turbulent dynamo, we perform three-dimensional MHD simulations interaction between wave and an inhomogeneous density distribution with shallow spectrum preshock medium. The postshock turbulence is mainly driven strongest contrast follows Kolmogorov scaling. resulting amplifies magnetic field. time evolution agrees prediction...
We study the streaming instability of GeV$-100~$GeV cosmic rays (CRs) and its damping in turbulent interstellar medium (ISM). find that is dominated by ion-neutral collisional weakly ionized molecular clouds, highly warm medium, nonlinear Landau Galactic halo. Only halo, speed CRs close to Alfv\'{e}n speed. Alfv\'{e}nic turbulence plays an important role both suppressing regulating diffusion via magnetic field line tangling, with effective mean free path observer frame determined scale...
Molecular gas is believed to be the fuel for star formation and nuclear activity in Seyfert galaxies. To explore role of magnetic fields funneling molecular into region, measurements embedded are needed. By applying new velocity gradient technique (VGT) ALMA PAWS's CO isotopolog data, we obtain first detection CO-associated several nearby galaxies their unprecedented high-resolution field maps. The VGT-measured globally agree with those inferred from existing HAWC+ dust polarization VLA...
Propagation of cosmic rays (CRs) in turbulent and magnetized astrophysical media is a long-standing problem that requires both understanding the properties magnetic fields their interaction with energetic particles. This review focuses on selected recent theoretical findings made based progress simulating magnetohydrodynamic (MHD) turbulence. In particular, we address perpendicular parallel propagation CRs identify conditions when superdiffusive diffusive. For diffusion, discuss problems...
ABSTRACT We investigate the driving of MHD turbulence by gravitational contraction using simulations an initially spherical, isothermal, magnetically supercritical molecular cloud core with transonic and trans-Alfvénic turbulence. perform a Helmholtz decomposition velocity field, evolution its solenoidal compressible parts, as well component along acceleration vector, proxy for infall field. find that (1) In spite being supercritical, first contracts to sheet perpendicular mean magnetic...
Abstract Magnetic fields and turbulence are fundamental to the evolutions of galaxies, yet their precise measurement analysis present significant challenges. The recently developed Velocity Gradient Technique (VGT), which capitalizes on anisotropy inherent in magnetohydrodynamic (MHD) turbulence, represents a new method for mapping magnetic galaxies using spectroscopic observations. Most validations VGT thus far have relied upon idealized MHD simulations, however, lack more complex dynamics...
This study aimed to investigate the effect of fractional exhaled nitric oxide (FeNO), a marker airway inflammation, together with small function tests in diagnosing cough variant asthma (CVA), particularly patients gastroesophageal reflux disease (GERD). retrospective cohort included adult chronic for more than eight weeks who were divided into CVA group and control group. Participants underwent pulmonary FeNO measurements. Statistical ROC curve analysis used assess diagnostic accuracy. had...
Abstract We investigated H i absorption toward a single pulsar, PSR J1644−4559, and its variability over timescales from days to years, using Murriyang, CSIRO’s Parkes Radio Telescope. Our 19 epochs of spectral observations, spanning 1.2 yr with intervals as short 1 day, provide the most comprehensive cadence coverage for monitoring date. identified two significant detections tiny-scale atomic structure (TSAS) spatial scales ranging lower limit ∼11 au an upper 165 au, both exhibiting...
A correct description of cosmic-ray (CR) diffusion in turbulent plasma is essential for many astrophysical and heliospheric problems. This paper aims to present physical behavior CRs actual magnetic fields, model which has been numerically tested. We perform test particle simulations compressible magnetohydrodynamic turbulence. obtain scattering spatial coefficients by tracing trajectories. find no resonance gap pitch-angle at 90$^\circ$. Our result confirms the dominance mirror interaction...
We introduce a non-resonant acceleration mechanism arising from the second adiabatic invariant in magnetic turbulence and apply it to study prompt emission spectra of gamma-ray bursts (GRBs). The contains both first- second-order Fermi acceleration, originating interacting turbulent reconnection dynamo processes. It leads hard electron energy distribution up cutoff at balance between synchrotron cooling. sufficient rate ensures rapid hardening any initial power-law with index $p \sim 1$,...