Jet/environment interactions in low-power radio galaxies

TL;DR

This paper presents XMM-Newton observations of low-power radio galaxies, revealing how their interactions with hot gas influence their structure, dynamics, and energy balance, especially highlighting the role of non-radiating particles in pressure support.

Contribution

It provides new observational evidence linking radio galaxy structures with hot gas interactions and the role of non-radiating particles in pressure balance, advancing understanding of source dynamics.

Findings

Naked jets require non-radiating particles for pressure balance.

Lobed sources do not require additional non-radiating particles.

Evidence suggests ICM entrainment supplies missing pressure.

Abstract

The interactions between low-power radio galaxies and their environments are thought to play a crucial role in supplying energy to offset cooling in the centres of groups and clusters. Such interactions are also important in determining large-scale radio structures and radio-source dynamics. I will discuss new XMM-Newton observations of the hot-gas environments of a representative sample of nine FRI radio galaxies, which show strong evidence for the importance of such interactions (including evidence for heating) and provide important new constraints on source dynamics and particle content. In particular I will show that the widely discussed apparent imbalance between the internal lobe pressure available from relativistic electrons and magnetic field and the external pressure of hot gas correlates with radio structure, so that naked jets require a large contribution from non-radiating particles, whereas lobed sources do not. This may provide the first direct observational evidence that entrainment of the ICM supplies the missing pressure.