Ionised outflows in z ~ 2.4 quasar host galaxies

AGN-driven outflowsare invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super massive black holes and their host galaxies. This work aims to detect the presence of extended ionised outflowsin luminous quasars where we expect the maximum activity both in star formation and in black hole accretion. Currently, there are only a few studies based on spatially resolved observations of outflowsat high redshift, $z>2$. We analyse a sample of six luminous (${\rm L>10^{47} \ erg/s}$) quasars at $z\sim2.4$, observed in H-bandusing the near-IR integral field spectrometer SINFONI at VLT. We perform a kinematic analysis of the [OIII] emission line at $\lambda = 5007\AA$. [OIII] has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km/s and line widths up to 1500 km/s. Using the spectroastrometric method we infer size of the ionised outflowsof up to $\sim$2 kpc. The properties of the ionised outflows, mass outflowrate, momentum rate and kinetic power, are correlated with the AGN luminosity. The increase in outflowrate with increasing AGN luminosity is consistent with the idea that a luminous AGN pushes away the surrounding gas through fast outflowsdriven by radiation pressure, which depends on the emitted luminosity. We derive mass outflowrates of about 6-700 M$_{\odot}$/yr for our sample, which are lower than those observed in molecular outflows. Indeed physical properties of ionised outflowsshow dependences on AGN luminosity which are similar to those of molecular outflowsbut indicating that the mass of ionised gas is smaller than that of the molecular one. Alternatively, this discrepancy between ionised and molecular outflowscould be explained with different acceleration mechanisms.