MUSE view of PDS 456: Kiloparsec-scale wind, extended ionized gas, and close environment

PDS 456 is the most luminous (Lbol ∼ 1047 erg s-1) radio-quiet quasar at z < 0.3 and can be regarded as a local counterpart of the powerful quasars shining at Cosmic Noon. It hosts a strong nuclear X-ray ultra-fast (∼0.3c) outflow, and a massive and clumpy CO (3- 2) molecular outflow extending up to ∼5 kpc from the nucleus. We analyzed the first MUSE Wide Field Mode (WFM) and Adaptive-Optics Narrow Field Mode (AO-NFM) optical integral field spectroscopic observations of PDS456. The AO-NFM observations provide an unprecedented spatial resolution, reaching up to ∼280 pc. Our findings reveal a complex circumgalactic medium around PDS 456, extending to a maximum projected size of ≈ 46 kpc. This includes a reservoir of gas with a mass of ∼107-108 M·, along with eight companion galaxies and a multi-phase outflow. WFM and NFM MUSE data reveal an outflow on a large scale (≈ 12 kpc from the quasar) in [O III], and on smaller scales (within 3 kpc) with higher resolution (about 280 pc) in Hα, respectively. The [O III] outflow mass rate is 2.3 ± 0.2 M· yr-1 which is significantly lower than those typically found in other luminous quasars. Remarkably, the Hα outflow shows a similar scale, morphology, and kinematics to the CO (3- 2) molecular outflow, with the latter dominating in terms of kinetic energy and mass outflow rate by two and one orders of magnitude, respectively. Our results therefore indicate that mergers, powerful active galactic nucleus (AGN) activity, and feedback through AGN-driven winds collectively contribute to shaping the host galaxy evolution of PDS 456, and likely that of similar objects at the brightest end of the AGN luminosity function across all redshifts. Moreover, the finding that the momentum boost of the total outflow deviates from the expected energy-conserving expansion for large-scale outflows highlights the need of novel AGN-driven outflow models to comprehensively interpret these phenomena.