Wide-angle tail galaxies in ATLAS

TL;DR

This study presents radio images and spectroscopic data of six Wide-Angle Tail galaxies from the ATLAS survey, revealing galaxy overdensities and large-scale structures, including potential merging systems, at redshifts 0.15 to 0.38.

Contribution

First detailed radio and spectroscopic analysis of WATs in ATLAS, uncovering large-scale structures and galaxy overdensities associated with these sources.

Findings

Detected galaxy overdensities near WATs at various redshifts.

Identified a large-scale structure with a 12 Mpc extent and complex sub-structures.

Observed a possible merging system with multiple interacting components.

Abstract

We present radio images of a sample of six Wide-Angle Tail (WAT) radio sources identified in the ATLAS 1.4 GHz radio survey, and new spectroscopic redshifts for four of these sources. These WATs are in the redshift range of 0.1469 - 0.3762, and we find evidence of galaxy overdensities in the vicinity of four of the WATs from either spectroscopic or photometric redshifts. We also present follow-up spectroscopic observations of the area surrounding the largest WAT, S1189, which is at a redshift of ~0.22. The spectroscopic observations, taken using the AAOmega spectrograph on the AAT, show an overdensity of galaxies at this redshift. The galaxies are spread over an unusually large area of ~12 Mpc with a velocity spread of ~4500 km/s. This large-scale structure includes a highly asymmetric FRI radio galaxy and also appears to host a radio relic. It may represent an unrelaxed system with different sub-structures interacting or merging with one another. We discuss the implications of these observations for future large-scale radio surveys.