A VLA Study of Newly-Discovered Southern Latitude Non-Thermal Filaments in the Galactic Center: Radio Continuum Total-intensity and Spectral Index Properties

TL;DR

This study uses VLA radio observations to analyze newly-discovered non-thermal filaments near the Galactic Center, revealing their properties and suggesting they are formed from cosmic rays generated by nearby sources or magnetic reconnection.

Contribution

First detailed radio continuum and spectral analysis of newly-discovered southern latitude NTFs, expanding understanding of their properties and origins.

Findings

NTFs have similar properties to larger known NTFs

Larger NTFs tend to have steeper spectral indices

NTFs likely formed from cosmic rays generated locally or via magnetic reconnection

Abstract

The non-thermal filament (NTF) radio structures clustered within a few hundred parsecs of the Galactic Center (GC) are apparently unique to this region of the Galaxy. Recent radio images of the GC using MeerKAT at 1 GHz have revealed a multitude of faint, previously unknown NTF bundles (NTFBs), some of which are comprised of as many as 10 or more individual filaments. In this work we present Very Large Array (VLA) observations at C- and X-bands (4 - 12 GHz) at arcsecond-scale resolutions of three of these newly-discovered NTFBs, all located at southern Galactic latitudes. These observations allow us to compare their total-intensity properties with those of the larger NTF population. We find that these targets generally possess properties similar to what is observed in the larger NTF population. However, the larger NTF population generally has steeper spectral index values than what we observe for our chosen targets. The results presented here based on the total-intensity properties of these structures indicate that the NTFs are likely all formed from Cosmic Rays (CRs). These CRs are either generated by a nearby compact source and then diffuse along the NTF lengths or are generated by extended, magnetized structures whose magnetic field undergoes reconnection with the NTF magnetic field.