WISDOM project -- VIII. Multi-scale feedback cycles in the brightest cluster galaxy NGC 0708

TL;DR

This study uses high-resolution ALMA and e-MERLIN observations to analyze the molecular gas dynamics and potential feedback mechanisms in the brightest galaxy of Abell 262, revealing complex gas structures and possible accretion or outflow processes.

Contribution

It provides detailed high-resolution imaging of molecular gas and continuum in NGC 0708, identifying a turbulent rotating disk and an anomalous blue-shifted feature, and discusses its possible origins.

Findings

Detection of a turbulent, rotating molecular gas disk.

Identification of a high-velocity blue-shifted feature near the galaxy center.

Discussion of potential inflow or outflow origins for the anomalous feature.

Abstract

We present high-resolution (synthesised beam size 0."088x0."083 or 25x23 pc$^2$) Atacama Large Millimetre/submillimetre Array (ALMA) $^{12}$CO(2-1) line and 236 GHz continuum observations, as well as 5 GHz enhanced Multi-Element Radio Linked Interferometer Network (e-MERLIN) continuum observations, of NGC 0708; the brightest galaxy in the low-mass galaxy cluster Abell 262. The line observations reveal a turbulent, rotating disc of molecular gas in the core of the galaxy, and a high-velocity, blue-shifted feature ~0."4 (~113 pc) from its centre. The sub-millimetre continuum emission peaks at the nucleus, but extends towards this anomalous CO emission feature. No corresponding elongation is found on the same spatial scales at 5 GHz with e-MERLIN. We discuss potential causes for the anomalous blue-shifted emission detected in this source, and conclude that it is most likely to be a low-mass in-falling filament of material condensing from the hot intra-cluster medium via chaotic cold accretion, but it is also possible that it is a jet-driven molecular outflow. We estimate the physical properties this structure has in these two scenarios, and show that either explanation is viable. We suggest future observations with integral field spectrographs will be able to determine the true cause of this anomalous emission, and provide further evidence for interaction between quenched cooling flows and mechanical feedback on both small and large scales in this source.