Cl J1449+0856: excited galaxies and multiple radio jets in the core of a mature galaxy cluster at z=2

ClJ1449+0856, a galaxy cluster at z=2, is an exemplary case to investigate everything from galaxy evolution in dense environments, to early-time energetic feedback in clusters, and the physics of the high-redshift intra-cluster medium (ICM). Despite its early epoch, ClJ1449 has now been detected in both diffuse X-ray emission and through the thermal Sunyaev Zel’Dovich effect - the lowest mass single SZ detection to date, confirming its virialised nature. In this talk, I will summarise the picture of high-redshift galaxy and cluster evolution emerging from ClJ1449 so far, and present our latest discoveries. Having uncovered a population of highly-excited, merging, star-forming galaxies in ClJ1449, we turn our attention to the excess radio emission at 3GHz. We discover multiple faint radio-jet emission sites in the cluster core - quite unlike the picture in local galaxy clusters, where Active Galactic Nuclei (AGN) activity is confined to a single central galaxy. I will discuss the implications of this kinetic feedback for energy injection into the ICM, gas accretion, and the infrared-radio correlation in dense environments. Finally, I introduce our future goal to quantify the cold ICM in ClJ1449.