The MURALES survey. IV. Searching for nuclear outflows in 3C radio
  galaxies at z < 0.3 with MUSE observations
  We analyze VLT/MUSE observations of 37 radio galaxies from the Third
Cambridge catalogue (3C) with redshift $<$0.3 searching for nuclear outflows of
ionized gas. These observations are part of the MURALES project (a MUse RAdio
Loud Emission line Snapshot survey), whose main goal is to explore the feedback
process in the most powerful radio-loud AGN. We applied a nonparametric
analysis to the [O~III] $\lambda$5007 emission line, whose asymmetries and
high-velocity wings reveal signatures of outflows. We find evidence of nuclear
outflows in 21 sources, with velocities between $\sim$400 - 1000 km s$^{-1}$,
outflowing masses of $\sim 10^5-10^7$ M$_\odot$, and a kinetic energy in the
range $\sim 10^{53} - 10^{56}$ erg. In addition, evidence for extended outflows
is found in the 2D gas velocity maps of 13 sources of the subclasses of
high-excitation (HEG) and broad-line (BLO) radio galaxies, with sizes between
0.4 and 20 kpc. We estimate a mass outflow rate in the range 0.4 - 30 M$_\odot$
yr$^{-1}$ and an energy deposition rate of ${\dot E}_{kin} \sim 10^{42}-10^{45}
$ erg s$^{-1}$. Comparing the jet power, the nuclear luminosity of the active
galactic nucleus, and the outflow kinetic energy rate, we find that outflows of
HEGs and BLOs are likely radiatively powered, while jets likely only play a
dominant role in galaxies with low excitation. The low loading factors we
measured suggest that these outflows are driven by momentum and not by energy.
Based on the gas masses, velocities, and energetics involved, we conclude that
the observed ionized outflows have a limited effect on the gas content or the
star formation in the host. In order to obtain a complete view of the feedback
process, observations exploring the complex multiphase structure of outflows
are required.
