Electromagnetic Helicity in Classical Physics

电磁螺旋度通量密度用于辐射系统

Electromagnetic helicity flux density for radiative systems

本文提出电磁螺旋度通量密度的概念，扩展了里纳尔-魏切特角分布并推广了劳伦公式，用于研究辐射系统中的螺旋度通量密度。

广义相对论规范不变的磁螺旋度输运：基本公式及其在中子星并合中的应用

General-Relativistic Gauge-Invariant Magnetic Helicity Transport: Basic Formulation and Application to Neutron Star Mergers

本研究提出广义相对论等离子体中磁螺旋度输运的协变规范不变公式，并首次将其应用于双中子星并合分析，发现并合遗迹外层存在全局螺旋度通量，可能影响后续大尺度磁场放大。

Using Convolutional Neural Networks for the Helicity Classification of Magnetic Fields

The presence of non-zero helicity in intergalactic magnetic fields is a smoking gun for their primordial origin since they have to be generated by processes that break CP invariance. As an experimental signature for the presence of helical magnetic fields, an estimator $Q$ based on the triple scalar product of the wave-vectors of photons generated in electromagnetic cascades from, e.g., TeV blazars, has been suggested previously. We propose to apply deep learning to helicity classification employing Convolutional Neural Networks and show that this method outperforms the $Q$ estimator.

Probing Intergalactic Magnetic Fields with Simulations of Electromagnetic Cascades

We determine the effect of intergalactic magnetic fields on the distribution of high energy gamma rays by performing three-dimensional Monte Carlo simulations of the development of gamma-ray-induced electromagnetic cascades in the magnetized intergalactic medium. We employ the so-called 'Large Sphere Observer' method to efficiently simulate blazar gamma ray halos. We study magnetic fields with a Batchelor spectrum and with maximal left- and right-handed helicities. We also consider the case of sources whose jets are tilted with respect to the line of sight. We verify the formation of extended …