Although now routinely incorporated into hydrodynamic simulations of galaxy evolution, the true importance of the feedback effect of the outflows driven by active galactic nuclei (AGN) remains uncertain from an observational perspective. This is due to a lack of accurate information on the densities, radial scales and level of dust extinction of the outflow regions. Here we use the unique capabilities of VLT/Xshooter to investigate the warm outflows in a representative sample of 9 local (0.06 < z < 0.15) ULIRGs with AGN nuclei and, for the first time, accurately quantify the key outflow properties. We find that the outflows are compact (0.05 < R [OIII] < 1.2 kpc), significantly reddened (median E(B-V)∼0.5 magnitudes), and have relatively high electron densities (3.4 < log 10 n e (cm −3 ) < 4.8). It is notable that the latter densities -obtained using trans-auroral [SII] and [OII] emission-line ratios -exceed those typically assumed for the warm, emission-line outflows in active galaxies, but are similar to those estimated for broad and narrow absorption line outflow systems detected in some type 1 AGN. Even if we make the most optimistic assumptions about the true (deprojected) outflow velocities, we find relatively modest mass outflow rates (0.07 <Ṁ < 11 M yr −1 ) and kinetic powers measured as a fraction of the AGN bolometric luminosities (4 × 10 −4 <Ė/L BOL < 1%). Therefore, although warm, AGN-driven outflows have the potential to strongly affect the star formation histories in the inner bulge regions (r ∼ 1kpc) of nearby ULIRGs, we lack evidence that they have a significant impact on the evolution of these rapidly evolving systems on larger scales.

Massive outflows driven by active galactic nuclei (AGN) are widely recognised to play a key role in the evolution of galaxies 1-4 , heating the ambient gas, expelling it from the nuclear regions, and thereby affecting the star formation histories of the galaxy bulges. It has been proposed that the powerful jets of relativistic particles launched by some AGN can both accelerate 5-7 and heat 8 the molecular gas, which often dominates the mass budgets of the outflows 5,9 . However, clear evidence for this mechanism in the form of detailed associations between the molecular gas kinematics and features in the radioemitting jets has been lacking. Here we show that the warm molecular hydrogen gas in the western radio lobe of the Seyfert galaxy IC5063 is moving at high velocities -up to +/-600 km s -1 -relative to the galaxy disk. This suggests that the molecules have been accelerated by fast shocks driven into the interstellar medium (ISM) by the expanding radio jets. These results demonstrate the general feasibility of accelerating molecular outflows in fast shocks driven by AGN. IC5063 (z=0.0113) is a massive early-type galaxy (M *~1 0 11 M  ) that hosts both a type II AGN and a powerful double-lobed radio source ( ! P 1.4GHz = 3 " 10 23 W Hz -1 ). The first signs of AGN-driven outflows in this object were provided by the detection of extended blue wings to the HI 21cm absorption feature and optical [OIII] emission lines at the site of the radio lobe 2.0 arcsec (0.45 kpc) to the west of its nucleus 10,11,12 . Subsequently, a blue wing was also detected in the CO(2-1) emission line profile of the integrated emission from the galaxy, providing evidence for molecular outflows 5 . However, the low spatial resolution of the mmwavelength CO observations of this and similar objects 5,6,7 prevented a direct link being established between the putative molecular outflows and the relativistic jets and lobes associated with the AGN.To overcome the resolution problem we have obtained deep, near-infrared long-slit spectroscopic observations of IC5063, taken with the slit aligned along the axis of the extended radio lobes and jets. The observations were made in good seeing conditions (FWHM=0.6 arcsec) and cover the H 2 1-0S(1)λ2.128µm and H 2 2-1S(2)λ2.154µm rotationalvibrational lines of molecular hydrogen, as well as the Brγλ2.166µm line emitted by the warm ionized gas at the same spatial locations in the galaxy. In Figure 1 we show a grey-scale representation of the long-slit spectrum, as well as line profiles extracted for three key regions

Tidal disruption events (TDEs), in which stars are gravitationally disrupted as they pass close to the supermassive black holes in the centres of galaxies 1 , are potentially important probes of strong gravity and accretion physics. Most TDEs have been discovered in large-area monitoring surveys of many 1000s of galaxies, and the rate deduced for such events is relatively low: one event every 10 4 -10 5 years per galaxy 2-4 . However, given the selection effects inherent in such surveys, considerable uncertainties remain about the conditions that favour TDEs. Here we report the detection of unusually strong and broad helium emission lines following a luminous optical flare (M v <-20.1 mag) in the nucleus of the nearby ultra-luminous infrared galaxy F01004-2237. The particular combination of variability and post-flare emission line spectrum observed in F01004-2237 is unlike any known supernova or active galactic nucleus. Therefore, the most plausible explanation for this phenomenon is a TDE-the first detected in a galaxy with an ongoing massive starburst. The fact that this event has been detected in repeat spectroscopic observations of a sample of 15 ultra-luminous infrared galaxies over a period of just 10 years suggests that the rate of TDEs is much higher in such objects than in the general galaxy population.Ultra-luminous infrared galaxies (ULIRGs: L IR > 10 12 L ¤ ) 5 represent the peaks of major, gas-rich galaxy mergers in which the merger-induced gas flows concentrate the gas into the nuclear regions, leading to high rates of star formation and accretion onto the central supermassive black holes. The nearby ULIRG F01004-2237 (RA: 01h 02m 50.007s and Dec: -22d 21m 57.22s (J2000); z=0.117835) was observed using deep spectroscopic observations in September 2015 as part of a study of 15 ULIRGs to examine the importance of the warm gas outflows driven by active galactic nuclei (AGNs) in such objects 6 . Many of its properties are typical of local ULIRGs, including relatively modest total stellar and supermassive black hole masses, and evidence for AGN activity in the form of blue-shifted high ionization emission lines 6 . However, it is unusual in the sense that it is one of the few ULIRGs in which Wolf-Rayet features have been detected at optical wavelengths 9 , indicating the presence of a population of ~3×10 4 Wolf-Rayet stars with ages 3-6 Myr (supplementary information). Also, unlike most ULIRGs for which the central starburst regions are heavily enshrouded in dust, this source has a compact nucleus that is barely resolved in optical and UV observations with the Hubble Space Telescope (HST) and has been attributed to a population of stars that is both young ( < 10 Myr) and massive (~3×10 8 M ¤ ) 10 . Together, these features suggest that we have an unusually clear view of the nuclear star forming regions in F01004-2237. However, the 2015 spectra are markedly different: the ~4660Å feature is a factor of 5.6+/-1.1 stronger in flux compared with 2000, and the blend has developed broad wings that extend up to...

We present an optical spectroscopic study of a 90 per cent complete sample of nearby ULIRGs (z < 0.175) with optical Seyfert nuclei, with the aim of investigating the nature of the nearnuclear (r 3.5 kpc) warm gas outflows. A high proportion (94 per cent) of our sample show disturbed emission line kinematics in the form of broad (FWHM > 500 km s −1 ) and/or strongly blueshifted ( V < −150 km s −1 ) emission line components. This proportion is significantly higher than found in a comparison sample of nearby ultraluminous infrared galaxies (ULIRGs) that lack optical Seyfert nuclei (19 per cent). We also find evidence that the emission line kinematics of the Sy-ULIRGs are more highly disturbed than those of samples of non-ULIRG Seyferts and Palomar-Green quasars in the sense that, on average, their [O III] λλ5007, 4959 emission lines are broader and more asymmetric.The Sy-ULIRG sample encompasses a wide diversity of emission line profiles. In most individual objects, we are able to fit the profiles of all the emission lines of different ionization with a kinematic model derived from the strong [O III] λλ4959, 5007 lines, using between two and five Gaussian components. From these fits, we derive diagnostic line ratios that are used to investigate the ionization mechanisms for the different kinematic components. We show that, in general, the line ratios are consistent with gas of supersolar abundance photoionized by a combination of AGN and starburst activity, with an increasing contribution from the AGN with increasing FWHM of the individual kinematic components, and the AGN contribution dominating for the broadest components. However, shock ionization cannot be ruled out in some cases. Our derived upper limits on the mass outflows rates and kinetic powers of the emission line outflows show that they can be as energetically significant as the neutral and molecular outflows in ULIRGs -consistent with the requirements of the hydrodynamic simulations that include AGN feedback. However, the uncertainties are large, and more accurate estimates of the radii, densities and reddening of the outflows are required to put these results on a firmer footing.

Young radio AGN are pivotal for our understanding of many of the still-debated aspects of AGN feedback. In this paper we present a study of the interstellar medium (ISM) in the compact, peaked-spectrum radio galaxy PKS B1934-63 using X-shooter observations. Most of the warm ionized gas resides within a circum-nuclear disk with a radius of about 200 pc that is likely to constitute the gas reservoir from which the central black hole feeds. On the other hand, we find a biconical outflow of warm ionized gas with an estimated radius of 59 ± 12 pc. This matches the radial extent of the radio source and suggests that the outflow is jet driven. Thanks to the superior wavelength coverage of the data, we can estimate the density of the warm ionized gas using the trans-auroral line technique, and we find that the outflowing gas has remarkably high density, up to log n e (cm −3 ) 5.5. The estimated mass outflow rate is low (Ṁ =10 −3 -10 −1 M yr −1 ), and the AGN feedback operates at relatively low efficiency (Ė/L bol ∼ 10 −4 -10 −3 %). In addition, optical and near-IR line ratios show that the expansion of the radio source drives fast shocks (with velocities v s 500 km s −1 ) that ionize and accelerate the outflowing gas. At odds with the properties of other compact, peaked-spectrum radio sources hosting warm ionized gas outflows, we do not find signs of kinematically disturbed or outflowing gas in phases colder than the warm ionized gas. We argue that this is due to the young age of our source and thus to the recent nature of the AGN-ISM interaction, and suggest that cold gas forms within the outflowing material and the shock-ionized outflowing gas of PKS B1934-63 did not have enough time to cool down and accumulate in a colder phase. This scenario is also supported by the multi-phase outflows of other compact and young radio sources in the literature.