Radio jets clearing the way through galaxies: the view from HI and molecular gas

TL;DR

This paper investigates how radio jets influence galaxy evolution by driving outflows of cold and molecular gas, using high-resolution observations to locate and analyze these interactions and their effects on the interstellar medium.

Contribution

It provides new high-resolution imaging evidence linking radio jets to cold gas outflows, supporting jet-driven outflow models and showing cold gas formation post-shock.

Findings

Radio jets are coincident with regions of cold gas outflows.

Cold gas can form after strong shocks and jet interactions.

Fast outflows are present even in weak radio sources.

Abstract

Massive gas outflows are considered a key component in the process of galaxy formation and evolution. Because of this, they are the topic of many studies aimed at learning more about their occurrence, location and physical conditions as well as the mechanism(s) at their origin. This contribution presents recent results on two of the best examples of jet-driven outflows traced by cold and molecular gas. Thanks to high-spatial resolution observations, we have been able to locate the region where the outflow occurs. This appears to be coincident with bright radio features and regions where the interaction between radio plasma jet and ISM is known to occur, thus strongly supporting the idea of jet-driven outflows. We have also imaged the distribution of the outflowing gas. The results clearly show the effect that expanding radio jets and lobes have on the ISM. This appears to be in good agreement with what predicted from numerical simulations. Furthermore, the results show that cold gas is associated with these powerful phenomena and can be formed - likely via efficient cooling - even after a strong interaction and fast shocks. The discovery of similar fast outflows of cold gas in weak radio sources is further increasing the relevance that the effect of the radio plasma can have on the surrounding medium and on the host galaxy.