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Considering the spatially separated polarization radiation and Faraday rotation regions to simulate complex interstellar media, we study synchrotron polarization gradient techniques' measurement capabilities. We explore how to trace the…

High Energy Astrophysical Phenomena · Physics 2021-07-14 Ru-Yue Wang , Jian-Fu Zhang , Alex Lazarian , Hua-Ping Xiao , Fu-Yuan Xiang

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 paper, we explore the ability of velocity gradients to…

Astrophysics of Galaxies · Physics 2018-09-26 A. Lazarian , Ka Ho Yuen , Ka Wai Ho , Junda Chen , Victor Lazarian , Zekun Lu , Bo Yang , Yue Hu

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 statistical techniques for studying magnetic fields in the…

Magnetic fields and turbulence are fundamental to the evolution of galaxies, yet their precise measurement and analysis present significant challenges. The recently developed Velocity Gradient Technique (VGT), which capitalizes on the…

Astrophysics of Galaxies · Physics 2025-03-07 Yue Hu , Joseph Whittingham , A. Lazarian , Christoph Pfrommer , Siyao Xu , Thomas Berlok

We study the magnetic field structures in six giant filaments associated with the spiral arms of the Milky Way by applying the Velocity Gradient technique (VGT) to the 13CO spectroscopic data from GRS, Fugin, and SEDIGSM surveys. Compared…

Based on the modern understanding of MHD turbulence theory, we propose a new method for measuring the spectral properties of magnetic turbulence by synchrotron polarization gradient analysis. Using synthetic polarization observational data,…

High Energy Astrophysical Phenomena · Physics 2025-05-08 Jianfu Zhang , Ziqi Liu

Magnetic fields play an important role in the evolution of molecular clouds and star formation. Using the Velocity Gradient Technique (VGT) model, we measured the magnetic field in Orion A using the 12CO, 13CO, and C18O (1-0) emission lines…

High-Sfrequency (HF) ray tracing in the complex ionospheric medium generally faces a fundamental trade-off between path accuracy and computational efficiency. This paper presents a high-fidelity Ray Tracing Method (RTM) synergistically…

Atmospheric and Oceanic Physics · Physics 2025-07-10 Qinglin Li , Wen Liu , Zhigang Zhang , Fengjuan Sun , Rong Chen , Zhongxin Deng , Zhiqiang Yao

Measuring magnetic fields in the interstellar medium and obtaining their distribution along line-of-sight is very challenging with the traditional techniques. The Velocity Gradient Technique (VGT), which utilizes anisotropy of…

Astrophysics of Galaxies · Physics 2022-04-27 Yue Hu , A. Lazarian , Q. Daniel Wang

Magnetic interaction between a weighing sample and an external magnetic field allows to measure characteristics of magnetic field (a sample with known magnetic characteristics), as well as the magnetic properties of a sample (a known…

Magnetic fields play an important role in the formation and evolution of a galaxy, but it is challenging to measure them by observation. Here we study the Seyfert galaxy NGC 3627's magnetic field orientations measured from the synchrotron…

Astrophysics of Galaxies · Physics 2022-12-07 Mingrui Liu , Yue Hu , A. Lazarian , Siyao Xu , Marian Soida

The mapping of the Galactic Magnetic Field (GMF) in three dimensions is essential to comprehend various astrophysical processes that occur within the Milky Way. This study endeavors to map the GMF by utilizing the latest MM2 technique, the…

Astrophysics of Galaxies · Physics 2023-07-12 Yue Hu , 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 inflationary gravitational wave is contaminated by the…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-29 Yue Hu , Ka Ho Yuen , Alex Lazarian

Star formation is a complex process that typically occurs in dense regions of molecular clouds mainly regulated by magnetic fields, magnetohydrodynamic (MHD) turbulence, and self-gravity. However, it remains a challenging endeavor to trace…

Astrophysics of Galaxies · Physics 2023-05-31 Tyler Schmaltz , Yue Hu , Alex Lazarian

In this study, we apply the Velocity Gradient Technique (VGT) to the merging Centaurus galaxy. We compare gradient maps derived from the PHANGS-ALMA survey using CO emission lines with magnetic field tracings from dust polarization data…

Astrophysics of Galaxies · Physics 2024-06-07 Quynh Lan Nguyen , Yue Hu , Alex Lazarian

Large pre-trained models have demonstrated extensive applications across various fields. However, fine-tuning these models for specific downstream tasks demands significant computational resources and storage. One fine-tuning method,…

Machine Learning · Computer Science 2025-07-02 Xuanbo Liu , Liu Liu , Fuxiang Wu , Fusheng Hao , Xianglong Liu

The atomic-to-molecular (HI-to-H$_2$) transition in photodissociation regions (PDRs) has been investigated over the last several decades through analytic and numerical modeling. However, classical PDR models typically assume uniform density…

Astrophysics of Galaxies · Physics 2021-01-06 Yue Hu , A. Lazarian , Shmuel Bialy

We explore how the velocity gradient technique (VGT) can be applied to absorbing media in the case of$^{13}$CO 2-1 emission. The VGT is a new way to trace magnetic fields in the plane of the sky using only spectroscopic observations. We…

Astrophysics of Galaxies · Physics 2019-06-13 Diego F. González-Casanova , A. Lazarian , Blakesley Burkhart

Magnetic fields have important or dominant effects in many areas of astrophysics, but have been very difficult to quantify. Spectropolarimetry from Ground State Alignment (GSA) has been suggested as a direct tracer of magnetic field in…

Astrophysics of Galaxies · Physics 2019-03-28 Huirong Yan , Cecile Gry , Francois Boulanger , Francesco Leone

We investigate the appearance of a low-frequency 1/f magnetic spectrum in three-dimensional incompressible magnetohydrodynamic turbulence using direct numerical simulations and virtual spacecraft sampling. Our goal is to determine how the…

Solar and Stellar Astrophysics · Physics 2026-05-28 Maia Brodiano , Facundo Pugliese , Nahuel Andrés , Pablo Dmitruk