# A new method for finding and characterizing galaxy groups via low-frequency radio surveys

## TL;DR

This paper introduces a novel radio survey-based method to identify and analyze high-redshift galaxy groups by linking radio lobe pressure to the intragroup medium, enabling mass and luminosity estimates.

## Contribution

The paper presents a new approach using low-frequency radio surveys to characterize galaxy groups' thermodynamic states at high redshifts, leveraging radio lobe pressure as a proxy.

## Key findings

- Radio lobe pressure reliably traces ICM pressure in FRII galaxies.
- Method estimates X-ray luminosity within a factor of 2 from radio data.
- Applicable to thousands of galaxy groups at z > 1.

## Abstract

We describe a new method for identifying and characterizing the thermodynamic state of large samples of evolved galaxy groups at high redshifts using high-resolution, low-frequency radio surveys, such as those that will be carried out with LOFAR and the Square Kilometre Array (SKA). We identify a sub-population of morphologically regular powerful (FRII) radio galaxies and demonstrate that, for this sub-population, the internal pressure of the radio lobes is a reliable tracer of the external intragroup/intracluster medium (ICM) pressure, and that the assumption of a universal pressure profile for relaxed groups enables the total mass and X-ray luminosity to be estimated. Using a sample of well-studied FRII radio galaxies, we demonstrate that our method enables the estimation of group/cluster X-ray luminosities over three orders of magnitude in luminosity to within a factor of ~2 from low-frequency radio properties alone. Our method could provide a powerful new tool for building samples of thousands of evolved galaxy groups at z>1 and characterizing their ICM.