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] λ5007 emission line, whose asymmetries and high-velocity wings reveal signatures of outflows. We find evidence of nuclear outflows in 21 sources, with velocities between ∼400 and 1000 km s−1, outflowing masses of ∼105 − 107 M⊙, and a kinetic energy in the range ∼1053 − 1056 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⊙ yr−1 and an energy deposition rate of Ėkin ∼ 1042 − 1045 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.

We analyze Near-Infrared Integral Field Spectrograph (NIFS) observations of the type-2 quasar (QSO2) SDSS J094521.33+173753.2 to investigate its warm molecular and ionized gas kinematics. This QSO2 has a bolometric luminosity of 10 45.7 erg s −1 and a redshift of z = 0.128. The K-band spectra provided by NIFS cover a range of 1.99-2.40 µm where low-ionization (Paα and Brδ), high ionization ([S XI]λ1.920 µm and [Si VI]λ1.963 µm) and warm molecular lines (from H 2 1-0S(5) to 1-0S(1)) are detected, allowing us to study the multi-phase gas kinematics. Our analysis reveals gas in ordinary rotation in all the emission lines detected and also outflowing gas in the case of the low-and high-ionization emission lines. In the case of the nuclear spectrum, which corresponds to a circular aperture of 0.3 (686 pc) in diameter, the warm molecular lines can be characterized using a single Gaussian component of full width at half maximum (FWHM)= 350-400 km s −1 , while Paα, Brδ, and [Si VI] are best fitted with two blue-shifted Gaussian components of FWHM∼800 and 1700 km s −1 , in addition to a narrow component of ∼300 km s −1 . We interpret the blue-shifted broad components as outflowing gas, which reaches the highest velocities, of up to −840 km s −1 , in the south-east direction (PA∼125 • ), extending up to a distance of ∼3.4 kpc from the nucleus. The ionized outflow has a maximum mass outflow rate of Ṁout, max =42-51 M yr −1 , and its kinetic power represents 0.1% of the quasar bolometric luminosity. VLA data of J0945 show extended radio emission (PA∼100 • ) that is aligned with the clumpy emission traced by the narrow component of the ionized lines up to scales of several kpc, and with the innermost part of the outflow (central ∼0.4 = 915 pc). Beyond that radius, at the edge of the radio jet, the high-velocity gas shows a different PA, of ∼125 • . This might be indicating that the line-emitting gas is being compressed and accelerated by the shocks generated by the radio jet.

The triggering mechanism for the most luminous, quasar-like active galactic nuclei (AGN) remains a source of debate, with some studies favouring triggering via galaxy mergers and others finding little evidence in support of this mechanism. Here, we present deep INT/WFC imaging observations of a complete sample of 48 optically-selected type 2 quasars – the QSOFEED sample (L[OIII] &gt; 108.5L⊙; z &lt; 0.14). Based on visual inspection by eight classifiers, we find clear evidence that galaxy interactions are the dominant triggering mechanism for quasar activity in the local universe, with 65$^{+6}_{-7}$ per cent of the type 2 quasar hosts showing morphological features consistent with galaxy mergers or encounters, compared with only 22$^{+5}_{-4}$ per cent of a stellar-mass- and redshift-matched comparison sample of non-AGN galaxies – a 5σ difference. The type 2 quasar hosts are a factor 3.0$^{+0.5}_{-0.8}$ more likely to be morphologically disturbed than their matched non-AGN counterparts, similar to our previous results for powerful 3CR radio AGN of comparable [OIII] emission-line luminosity and redshift. In contrast to the idea that quasars are triggered at the peaks of galaxy mergers as the two nuclei coalesce, and only become visible post-coalescence, the majority of morphologically-disturbed type 2 quasar sources in our sample are observed in the pre-coalescence phase (61$^{+8}_{-9}$ per cent). We argue that much of the apparent ambiguity that surrounds observational results in this field is a result of differences in the surface brightness depths of the observations, combined with the effects of cosmological surface brightness dimming.