Abstract: The standard merger-driven galaxy evolutionary scenario for the formation of massive galaxies predicts a phase of deeply “buried” supermassive black hole growth coexisting with a starburst before feedback phenomena deplete the cold molecular gas reservoir of the galaxy and an optically luminous quasar (QSO) is revealed. Given the relevance of multi-phase outflow phenomena in AGN feedback models, constraining the gas content in high-z AGN with outflows detected in the ionised phase is a compelling hot topic in extragalactic astronomy.
We present ALMA observations of the CO(2-1) and CO(5-4) emissions in two X-ray selected luminous obscured QSOs at z~1.5, adding a missing piece to the understanding of their outflow properties, these targets being the most extreme and the best characterised so far in the ionised outflow component at such redshift.
These two obscured QSOs were selected from the XMM-COSMOS survey and are hosted in remarkably different host galaxies, one being a starburst while the other being a normal MS galaxy.
Thanks to ALMA sensitive data, we observe both the indirect evidence of AGN feedback in action, finding a low molecular gas fraction and depletion timescale with respect to samples of inactive galaxies with matched host properties, and the molecular counterpart of the ionised wind, with both blue- and red-shifted velocities exceeding 500 km/s and mass outflow rate up to ~2500 Msun/year.
Complementing the ALMA submm observations with optical rest frame data, we investigate how the molecular and ionised mass outflow rate correlate with star formation rate, galaxy stellar mass and the AGN luminosity, by assembling the largest (x3 than in previous works) sample of AGN at high redshift (z>1).
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