Tracing Magnetic Fields with the Gradient Technique: Spatial Filtering Effect and Use of Interferometers

Probing magnetic fields in astrophysical environments is both important and challenging. The Gradient Technique (GT) is a new tool for tracing magnetic fields, rooted in the properties of magnetohydrodynamic (MHD) turbulence and turbulent magnetic reconnection. In this work, we examine the performance of GT when applied to synthetic synchrotron emission and spectroscopic data obtained from sub-Alfv\'enic and trans-Alfv\'enic MHD simulations. We demonstrate the improved accuracy of GT in tracing magnetic fields in the absence of low-spatial frequencies. Additionally, we apply a low-spatial frequency filter to a diffuse neutral hydrogen region selected from the GALFA-\ion{H}{1} survey. Our results show an increased alignment between the magnetic fields inferred from GT and the Planck 353 GHz polarization measurements.