Barbell-shaped giant radio galaxy with ~100 kpc kink in the jet

TL;DR

This study investigates a giant radio galaxy with a unique barbell shape and a 100 kpc kink in its jet, revealing its structure, magnetic field, and age, and discussing possible formation mechanisms within a low-mass galaxy cluster.

Contribution

First detailed multi-frequency radio and optical study of a peculiar giant radio galaxy with a barbell shape and large jet kink, providing insights into its structure, environment, and evolution.

Findings

Size of the GRG is approximately 1.83 Mpc.

Jet kink extends about 100 kpc and may result from precession, instabilities, or magnetic reconnection.

Magnetic field strength estimated at ~5 μG with spectral ages between 110-200 million years.

Abstract

We present for the first time a study of peculiar giant radio galaxy (GRG) J223301+131502 using deep multi-frequency radio observations from GMRT (323, 612, and 1300 MHz) and LOFAR (144 MHz) along with optical spectroscopic observations with the WHT~4.2m optical telescope. Our observations have firmly established its redshift of 0.09956 and unveiled its exceptional jet structure extending more than $\sim$ 200 kpc leading to a peculiar kink structure of $\sim$ 100 kpc. We measure the overall size of this GRG to be $\sim$ 1.83 Mpc; it exhibits lobes without any prominent hotspots and closely resembles a barbell. Our deep low-frequency radio maps clearly reveal the steep-spectrum diffuse emission from the lobes of the GRG. The magnetic field strength of $\sim$ 5 $\mu$G and spectral ages between about 110 to 200 mega years for the radio lobes were estimated using radio data from LOFAR 144 MHz observations and GMRT 323 and 612 MHz observations. We discuss the possible causes leading to the formation of the observed kink feature for the GRG, which includes precession of the jet axis, development of instabilities and magnetic reconnection. Despite its enormous size, the Barbell GRG is found to be residing in a low-mass (M$_{200} \sim 10^{14}$ $\rm M_{\odot}$) galaxy cluster. This GRG with two-sided large-scale jets with a kink and diffuse outer lobes residing in a cluster environment provides an opportunity to explore the structure and growth of GRGs in different environments.