MIGHTEE: the dark matter haloes, duty cycle, and mechanical feedback from radio-AGN up to z ∼ 2.5

Abstract

Radio-AGNs (active galactic nuclei) are observed to be more strongly clustered than non-active galaxies, though it is unclear whether this is simply due to their preference for massive host galaxies, or if they reside in distinct environments beyond this mass dependence. Using data from three fields covered by the MIGHTEE survey, we measure the angular two-point cross-correlation functions with a large, stellar mass-limited population of near-infrared selected galaxies, overcoming limitations of previous single-deep-field studies. By fitting halo occupation distribution models, we infer the galaxy bias parameters, b, for radio-AGN in three redshift ranges with median redshifts of (Formula presented), (Formula presented), and (Formula presented), finding (Formula presented), (Formula presented), and (Formula presented), respectively. The typical dark matter halo mass decreases with increasing redshift: (Formula presented), (Formula presented), and (Formula presented), which we attribute to the increased abundance of cold gas required to fuel AGN activity at earlier times. The AGN duty cycle is determined to be (Formula presented) per cent, and we estimate that the total energy radiated by radio-jets over (Formula presented) is (Formula presented) per halo, which is sufficient to account for the observed excess heating of gas beyond that of gravitational collapse. Comparing the typical dark matter halo masses to the values obtained for the control sample, we find that the halo masses of radio-AGN are (Formula presented), (Formula presented), and (Formula presented) times greater than those of the stellar mass- and redshift-matched galaxies. This difference could arise because AGN feedback suppresses stellar mass growth while leaving halo mass unchanged, or because radio-AGN preferentially reside in earlier forming haloes which are more strongly clustered.