The properties of the extended warm ionised gas around low-redshift QSOs
  and the lack of extended high-velocity outflows
  (Abridged) We present a detailed analysis of a large sample of 31
low-redshift, mostly radio-quiet type 1 QSOs observed with integral field
spectroscopy to study their extended emission-line regions (EELRs). We focus on
the ionisation state of the gas, size and luminosity of extended narrow line
regions (ENLRs), which corresponds to those parts of the EELR dominated by
ionisation from the QSO, as well as the kinematics of the ionised gas. We
detect EELRs around 19 of our 31 QSOs (61%) after deblending the unresolved QSO
emission and the extended host galaxy light in the integral field data. We
identify 13 EELRs to be entirely ionised by the QSO radiation, 3 EELRs are
composed of HII regions and 3 EELRs display signatures of both ionisation
mechanisms at different locations. The typical size of the ENLR is 10kpc at a
median nuclear [OIII] luminosity of log(L([OIII])/[erg/s])=42.7+-0.15. We show
that the ENLR sizes are least a factor of 2 larger than determined with HST,
but are consistent with those of recently reported type 2 QSOs at matching
[OIII] luminosities. The ENLR of type 1 and type 2 QSOs appear to follow the
same size-luminosity relation. Furthermore, we show for the first time that the
ENLR size is much better correlated with the QSO continuum luminosity than with
the total/nuclear [OIII] luminosity. We show that ENLR luminosity and radio
luminosity are correlated, and argue that radio jets even in radio-quiet QSOs
are important for shaping the properties of the ENLR. Strikingly, the
kinematics of the ionised gas is quiescent and likely gravitationally driven in
the majority of cases and we find only 3 objects with radial gas velocities
exceeding 400km/s in specific regions of the EELR that can be associate with
radio jets. In general, these are significantly lower outflow velocities and
detection rates compared to starburst galaxies or radio-loud QSOs.
