Analyzing the Intrinsic Magnetic Field in the Galactic Center Radio Arc

The Radio Arc is a system of organized nonthermal filaments (NTFs) located within the Galactic center (GC) region of the Milky Way. Recent observations of the Radio Arc NTFs revealed a magnetic field that alternates between being parallel and rotated with respect to the orientation of the filaments. This pattern is in stark contrast to the predominantly parallel magnetic field orientations observed in other GC NTFs. To help elucidate the origin of this pattern, we analyze spectro-polarimetric data of the Radio Arc NTFs using an Australian Telescope Compact Array data set covering the continuous frequency range from ∼4 to 11 GHz at a spectral resolution of 2 MHz. We fit depolarization models to the spectral polarization data to characterize Faraday effects along the line of sight. We assess whether structures local to the Radio Arc NTFs may contribute to the unusual magnetic field orientation. External Faraday effects are identified as the most likely origin of the rotation observed for the Radio Arc NTFs; however, internal Faraday effects are also found to be likely in regions of parallel magnetic field. The increased likelihood of internal Faraday effects in parallel magnetic field regions may be attributed to the effects of structures local to the GC. One such structure could be the Radio Shell local to the Radio Arc NTFs. Future studies are needed to determine whether this alternating magnetic field pattern is present in other multi-stranded NTFs, or is a unique property resulting from the complex interstellar region local to the Radio Arc NTFs.

Role of avoided crossing and weak value amplification on enhanced Faraday effect in magnetoplasmonic systems

Enhancement of magneto-optical effects in hybrid magneto-plasmonic systems has attracted considerable recent attention because of their potential for building non-reciprocal nanophotonic devices. Quantitative understanding of the fundamental origin and contributing mechanisms for the enhancement is crucial for optimizing applications. Here, we unravel different physical origins of the giant enhancement of Faraday rotation and ellipticity in a hybrid magneto-plasmonic system, namely, waveguided magneto-plasmonic crystal for excitation with transverse electric (TE) and transverse magnetic (TM) polarized light. With TE polarization excitation, where the surface plasmons are not directly excited, the natural weak value amplification of Faraday effects appearing due to the spectral domain interference of Fano resonance is the dominant cause of the enhancement. For TM polarization excitation, on the other hand, waveguide-plasmon strong coupling and its universal manifestation of avoided crossing plays an important role, leading to maximum enhancement of the magneto-optical effects in the avoided crossing regime.

Data Reduction and Imaging of Gravitational Lens System Class B0631+519

The present paper describes reduction procedures and imaging of radio astronomical data from the gravitational lens system CLASS B0631+519 acquired by e-MERLIN interferometer. The source has been previously imaged with VLA, MERLIN and the VLBA interferometers. Data reduction and polarisation calibration procedures will provide data on Faraday effects such as Faraday rotation and depolarization between lensed images that in turn carry information on large and small-scale magnetic fields in the lensing galaxy.Reduction of data and imaging of the radio astronomical source have been achieved using Astronomical Image Processing System (AIPS) in conjunction with automatic data reduction pipelines that performed specific data processing steps. As a result, the sky map for the gravitational lens system has been successfully acquired and accuracy comparing the generated map to sky maps of the source produced by different authors has been confirmed.

Multifield-tunable magneto-optical effects in electron- and hole-doped nitrogen–graphene crystals

The magneto-optical effects play a prominent role in probing the exotic magnetism in 2D materials. Here, we present that the magneto-optical Kerr and Faraday effects in carrier-doped nitrogen–graphene crystals can be effectively mediated by electric, magnetic, and strain fields. Our results indicate that nitrogen–graphene crystals provide a novel 2D material platform for nano-spintronics and magneto-optical devices.