Speaker
Description
Radio-jets are thought to play a key role in shaping the host galaxy/black hole interplay in AGN. Given the recent advent of new large-area radio surveys, the sample of radio-loud (RL) quasars at z>5 doubled in the last few years. However, little is currently known about radio-mode feedback at such redshifts. Initial sub-mm observations of a few RL quasars provide intriguing clues of the impact of radio-jets on the cool interstellar medium (ISM), but any more general result is hampered by the limited amount of data.
Here, I will present new ALMA [CII] and continuum observations of the host galaxies of 26 z>5 RL quasars, tripling the sample with such data yet. We recover a great variety of cases: 15% of the sources show signatures of mergers and/or complex morphologies, the continuum of 15% of them is dominated by the radio jet, while 25% have no detections in line nor continuum. Intriguingly, we observe a systematic deficit of [CII] emission in RL quasars with respect to what recovered around radio-quiet (RQ) ones, irrespective of their rest-frame UV luminosities. This suggests that radio-jets may have a key role in hindering cool gas emission at high-z. Moreover, we observe a dearth of massive companion sources within tens of kpcs around RL quasars, with respect to what recovered around RQ ones. This is in contrast with what is observed at lower-z.
Finally, I will discuss how further multi-wavelength and multi-scale observations, e.g., from VLT/MUSE, JWST or VLA, will help us to shed light on the complexity of radio-jets and interstellar medium interaction and on the environments of RL quasars in the early universe.