A giant radio galaxy with three cycles of episodic jet activity from LoTSS DR2

TL;DR

This paper reports the discovery of a giant triple-double radio galaxy with three episodes of jet activity, providing insights into the growth and evolution of such rare giant radio sources.

Contribution

We discovered a rare giant triple-double radio galaxy with three distinct jet episodes, expanding understanding of episodic jet activity in massive radio galaxies.

Findings

The galaxy has a total size of 1.35 Mpc.

It shows three episodes of jet activity with sizes 118 kpc, 572 kpc, and 1.35 Mpc.

Jet power may decrease over time.

Abstract

The excellent sensitivity and optimum resolution of LoTSS DR2 at 144 MHz has enabled us to discover a giant radio galaxy (J1225+4011) with three distinct episodes of jet activity, making it a member of a class of objects called triple-double radio galaxies (TDRGs). The source extends overall up to 1.35 Mpc in projected size, with the second episode extending to 572 kpc, and the inner episode to 118 kpc. J1225+4011 is only the fourth radio source showing a triple-double radio structure. All four sources have overall sizes greater than 700 kpc, making them giants. We also present the LoTSS 144 MHz map of the TDRG J0929+4146 and report its updated size. Lastly, we have summarised and discussed the radio properties of all TDRGs for the first time to understand their growth and evolution. Our observations suggest that the power of their jets may decrease with time.