130 citations · 1k across the 31 of their papers we have counts for
31 papers
The stable "Unstable Natural Media" due to the presence of turbulence
Ka Wai Ho, Ka Ho Yuen, Alex Lazarian
The term "unstable neutral media" (UNM) has traditionally been used to describe the transient phase formed between the warm and cold neutral hydrogen (HI) phases and has not been t…
Neutral hydrogen filaments in interstellar media: Are they physical?
Ka Ho Yuen, Ka Wai Ho, Chi Yan Law +1
The trending term "filament" is extensively used in the interstellar medium (ISM) and the star formation community, and is believed to be one of the most important objects that gau…
Unveiling polarized emission from interstellar dust of the Large Magellanic Cloud with Planck
D. Alina, J. -Ph. Bernard, K. H. Yuen +5
Polarization of interstellar dust emission is a powerful probe of dust properties and magnetic field structure. Yet studies of external galaxies are hampered by foreground dust con…
Turbulent universal galactic Kolmogorov velocity cascade over 6 decades
Ka Ho Yuen, Ka Wai Ho, Chi Yan Law +2
We report the evidence for the existence of the universal, continuous turbulent cascade of velocity fluctuations with Kolmogorov -5/3 slope spanning 6 orders of length scales, from…
Magnetic field strength from turbulence theory (I): Using differential measure approach (DMA)
A. Lazarian, Ka Ho Yuen, Dmitri Pogosyan
The mean plane-of-sky magnetic field strength is traditionally obtained from the combination of polarization and spectroscopic data using the Davis-Chandrasekhar-Fermi (DCF) techni…
Correlation of velocity and density contributions to spectroscopic channel maps: Reality check on Kalberla et.al (2022)
Ka Ho Yuen, Ka Wai Ho, Alex Lazarian
The existence of magnetized turbulence in the interstellar HI is well accepted. A number of techniques to obtain turbulence spectrum and magnetic field direction and strength have…
Is the recently discovered large scale filamentary feature Cattail in the cold or unstable phase?
Ka Ho Yuen, Avi Chen, Ka Wai Ho +1
A recent publication (Li et al. 2021) discovered one of the largest filamentary neutral hydrogen features dubbed Cattail from high resolution FAST observations that might be a new…
How the existence of unstable neutral media restricts the aspect ratio of cold neutral media?
Ka Wai Ho, Ka Ho Yuen, Alex Lazarian
The ubiquity of very thin and lengthy cold neutral media (CNM) has been reported by multiple authors in the HI community. Yet, the reason of how the CNM can be so long and lengthy…
Technique for separating velocity and density contributions in spectroscopic data and its application to studying turbulence and magnetic fields
Ka Ho Yuen, Ka Wai Ho, Alex Lazarian
Based on the theoretical description of Position-Position-Velocity(PPV) statistics in Lazarian & Pogosyan(2000), we introduce a new technique called the Velocity Decomposition Algo…
Magnetic Field Morphology in Interstellar Clouds with the Velocity Gradient Technique
Yue Hu, Ka Ho Yuen, Victor Lazarian +6
Magnetic fields, while ubiquitous in many astrophysical environments, are challenging to measure observationally. Based on the properties of anisotropy of eddies in magnetized turb…
Obtaining magnetic field strength using differential measure approach and velocity channel maps
Alex Lazarian, Ka Ho Yuen, Dmitri Pogosyan
We introduce two new ways of obtaining the strength of plane-of-sky (POS) magnetic field by simultaneous use of spectroscopic Doppler-shifted lines and the information on magnetic…
Velocity Gradient in the Presence of Self-Gravity: Identifying Gravity-induced Inflow and Determining Collapsing Stage
Yue Hu, Alex Lazarian, Ka Ho Yuen
Understanding how star formation is regulated requires studying the energy balance between turbulence, magnetic fields, stellar feedback, and gravity within molecular clouds. Howev…
Curvature of magnetic field lines in compressible magnetized turbulence: Statistics, magnetization predictions, gradient curvature, modes and self-gravitating media
Ka Ho Yuen, A. Lazarian
Magnetic field lines in interstellar media have a rich morphology, which could be characterized by geometrical parameters such as curvature and torsion. In this paper, we explore t…
A Synergy of the Velocity Gradients Technique and the Probability Density Functions for Identifying Gravitational Collapse in Self-Absorbing Media
Yue Hu, A. Lazarian
The Velocity Gradients Technique (VGT) and the Probability Density Functions (PDFs) of mass density are tools to study turbulence, magnetic fields, and self-gravity in molecular cl…
Predictions of Cosmic Microwave Background Foregrounds Dust Polarization Using Velocity Gradients
Yue Hu, Ka Ho Yuen, Alex Lazarian
The observations of fluctuations in the cosmic microwave background provide information about primordial inhomogeneities in the universe. However, the B-mode polarization of the in…
Intensity Gradients Technique: Synergy with Velocity Gradients and Polarization Studies
Yue Hu, Ka Ho Yuen, Alex Lazarian
Magnetic fields are ubiquitous in the interstellar medium but are notoriously difficult to study through observation. Making use of the advances in our understanding of MHD turbule…
Tracing Magnetic Field with Synchrotron Polarization Gradients: Parameter Study
Jian-Fu Zhang, Alex Lazarian, Ka Wai Ho +3
We employ synthetic observations obtained with MHD simulations to study how to trace the distribution of turbulent magnetic fields using the synchrotron polarization gradient techn…
Comment on Clark et al. (2019) "The Physical Nature of Neutral Hydrogen Intensity Structure"
Ka Ho Yuen, Yue Hu, A. Lazarian +1
A recent publication by Clark et.al (2019, CX19) uses both GALFA-HI observational data and numerical simulations to address the nature of intensity fluctuations in Position-Positio…
Tracing Multi-Scale Magnetic Field Structure Using Multiple Chemical Tracers in Giant Molecular Clouds
Yue Hu, Ka Ho Yuen, A. Lazarian +3
Probing magnetic fields in Giant Molecular Clouds is often challenging. Fortunately, recently simulations show that analysis of velocity gradients (the Velocity Gradient Technique)…
A comparison between Faraday Tomography and Synchrotron Polarization Gradients
Ka Wai Ho, Ka Ho Yuen, Po Kin Leung +1
Observations of synchrotron polarization at multiple frequencies in the presence of Faraday rotation can provide a way to reconstruct the 3D magnetic field distribution. In this pa…
Tracing magnetic field morphology using the Velocity Gradient Technique in the presence of CO self-absorption
Cheng-Han Hsieh, Yue Hu, Shih-Ping Lai +5
Probing magnetic fields in self-gravitating molecular clouds are generally difficult even with the use of the polarimetry. Based on the properties of magneto-hydrodynamic (MHD) tur…
Statistical tracing of magnetic fields: comparing and improving the techniques
Ka Ho Yuen, Junda Chen, Yue Hu +9
Magnetohydrodynamic(MHD) turbulence displays velocity anisotropies which reflect the direction of the magnetic field. This anisotropy has led to the development of a number of stat…
Improving the Accuracy of Magnetic Field Tracing by Velocity Gradients: Principal Component Analysis
Yue Hu, Ka Ho Yuen, A. Lazarian
Tracing of the magnetic field with Velocity Gradient Technique (VGT) allows observers to probe magnetic field directions with spectroscopic data. In this paper, we employ the metho…
Distribution of velocity gradient orientations: Mapping magnetization with the Velocity Gradient Technique
A. Lazarian, Ka Ho Yuen, Ka Wai Ho +5
Recent developments of the Velocity Gradient Technique (VGT) show that the velocity gradients provide a reliable tracing of magnetic field direction in turbulent plasmas. In this p…