Non-thermal filaments and AGN recurrent activity in the galaxy group Nest200047: a LOFAR, uGMRT, MeerKAT, VLA radio spectral analysis

TL;DR

This paper analyzes the complex radio structures and spectral properties of non-thermal filaments in the galaxy group Nest200047, revealing recurrent AGN activity and plasma dynamics through multi-frequency radio observations.

Contribution

It provides a detailed spectral and morphological analysis of non-thermal filaments in Nest200047 using data from LOFAR, uGMRT, MeerKAT, and VLA, highlighting recurrent AGN activity.

Findings

Discovery of new filamentary emission structures.

Filaments have steep, curved spectra with constant spectral index profiles.

Jet active phases last 50-100 Myr with short inactive periods.

Abstract

Nest200047 is a clear example of multiple radio bubbles from an Active Galactic Nucleus (AGN) in a galaxy group, featuring non-thermal filaments likely shaped by buoyancy, gas motions, and stabilized by magnetic fields. This study presents high-quality data obtained from uGMRT, MeerKAT, and VLA, alongside existing LOFAR data, to analyze the system's morphology and spectrum over a broad frequency range (53-1518 MHz). Our findings reveal new filamentary emission in the inner 60 kpc, surrounding and extending from the inner bubbles and jets, suggesting complex dynamical evolution of the non-thermal plasma in the group core. The filaments have widths of a few kpc and lengths from tens to hundreds of kpc, with a steep and curved radio spectrum ($\rm \alpha=1\sim2$). They exhibit a constant spectral index profile along their length, implying particles are either (re-)accelerated together or move at super-Alfvenic speeds. Spectral aging analysis yields jet active times between 50 and 100 Myr with short inactive phases, suggesting continuous energy injection typical of AGN feedback in galaxy groups. This study highlights the potential of combining high-quality radio data to understand recurrent jet activity and feedback, with implications for future research with the SKA observatory.