Thursday

I will discuss a new method to identify and characterize the thermodynamic state of large samples of evolved galaxy groups at high redshifts using high-resolution, low-frequency radio surveys. I will demonstrate that for the sub-population of morphologically regular FRII (classical double) radio galaxies, the internal pressure of the radio lobes is a reliable tracer of the external ICM pressure, and therefore that the assumption of a universal pressure profile (cf. Arnaud et al. 2010) enables the total mass and X-ray luminosity of the group/cluster environment to be estimated from the properties of the embedded radio galaxy. Using a sample of well-studied FRII radio galaxies I will demonstrate that this method enables the estimation of group/cluster X-ray luminosities to within a factor of ~2 from low-frequency radio properties alone. Our method offer the prospect of finding and characterizing the thermodynamic state of samples of ~10,000s of galaxy groups at z>1 with LOFAR and beyond z=2 with future surveys such as those planned with the SKA.