The radio source in Abell 980: A Detached-Double-Double Radio Galaxy?

Abstract

Abstract It is argued that the new morphological and spectral information gleaned from the recently published LoFAR Two metre Sky Survey data release 2 (LoTSS-2 at 144 MHz) observations of the cluster Abell 980 (A980), in combination with its existing GMRT and VLA observations at higher frequencies, provide the much-needed evidence to strengthen the proposal that the cluster’s radio emission comes mainly from two double radio sources, both produced by the brightest cluster galaxy (BCG) in two major episodes of jet activity. The two radio lobes left from the previous activity have become diffuse and developed an ultra-steep radio spectrum while rising buoyantly through the confining hot intra-cluster medium (ICM) and, concomitantly, the host galaxy has drifted to the cluster centre and entered a new active phase manifested by a coinciding younger double radio source. The new observational results and arguments presented here bolster the case that the old and young double radio sources in A980 conjointly represent a ‘double-double’ radio galaxy whose two lobe pairs have lost colinearity due to the (lateral) drift of their parent galaxy, making this system by far the most plausible case of a ‘Detached-Double-Double Radio Galaxy’ (dDDRG).