© ESO 2020Marasco, A.Cresci, G.Nardini, E.Mannucci, F.Marconi, A.Tozzi, P.Amiri, A.Venturi, G.Piconcelli, E.Lanzuisi, G.Tombesi, F.Mingozzi, M.Perna, M.Carniani, S.Brusa, M.Di Serego Alighieri, S.Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-07372021-04-192021-04-192020-11-24Astronomy and Astrophysics 644: A15(2020)0004-6361https://www.aanda.org/articles/aa/abs/2020/12/aa38889-20/aa38889-20.htmlhttp://hdl.handle.net/20.500.12666/423The reduced datacubes are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/644/A15.We used MUSE adaptive optics data in narrow field mode to study the properties of the ionised gas in MR 2251-178 and PG 1126-041, two nearby (z similar or equal to 0.06) bright quasars (QSOs) hosting sub-pc scale ultra-fast outflows (UFOs) detected in the X-ray band. We decomposed the optical emission from diffuse gas into a low- and a high-velocity components. The former is characterised by a clean, regular velocity field and a low (similar to 80 km s(-1)) velocity dispersion. It traces regularly rotating gas in PG 1126-041, while in MR 2251-178 it is possibly associated with tidal debris from a recent merger or flyby. The other component is found to be extended up to a few kpc from the nuclei, and shows a high (similar to 800 km s(-1)) velocity dispersion and a blue-shifted mean velocity, as is expected from outflows driven by active galactic nuclei (AGN). We estimate mass outflow rates up to a few M-circle dot yr(-1) and kinetic efficiencies L-KIN/L-BOL between 1-4x10(-4), in line with those of galaxies hosting AGN of similar luminosities. The momentum rates of these ionised outflows are comparable to those measured for the UFOs at sub-pc scales, which is consistent with a momentum-driven wind propagation. Pure energy-driven winds are excluded unless about 100x additional momentum is locked in massive molecular winds. In comparing the outflow properties of our sources with those of a small sample of well-studied QSOs hosting UFOs from the literature, we find that winds seem to systematically lie either in a momentum-driven or an energy-driven regime, indicating that these two theoretical models bracket the physics of AGN-driven winds very well.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttps://creativecommons.org/licenses/by-nc-nd/4.0/Quasars: individualMR 2251-178PG 1126−041ISM; jets and outflowsTechniques: imaging spectroscopyGalaxies: ISMinfo:eu-repo/semantics/article10.1051/0004-6361/2020388891432-0746info:eu-repo/semantics/openAccess