In this paper we describe the first data release of the UltraVISTA near-infrared imaging survey of the COSMOS field. We summarise the key goals and design of the survey and provide a detailed description of our data reduction techniques. We provide stacked, skysubtracted images in Y JHK s and narrow-band filters constructed from data collected during the first year of UltraVISTA observations. Our stacked images reach 5σ AB depths in an aperture of 2 diameter of ∼25 in Y and ∼24 in JHK s bands and all have subarcsecond seeing. To this 5σ limit, our K s catalogue contains 216 268 sources. We carry out a series of quality assessment tests on our images and catalogues, comparing our stacks with existing catalogues. The 1σ astrometric rms in both directions for stars selected with 17.0 < K s (AB) <

We present intermediate-resolution, wide-wavelength coverage spectra for a complete sample of 14 compact radio sources taken with the aim of investigating the impact of the nuclear activity on the circumnuclear interstellar medium (ISM) in the early stages of radio source evolution. We observe spatially extended line emission (up to ∼20 kpc) in the majority of sources which is consistent with a quiescent halo. In the nuclear apertures we observe broad, highly complex emission-line profiles. Multiple Gaussian modelling of the [O III]λ5007 line reveals between two and four components which can have velocity widths [full width at halfmaximum (FWHM)] and blueshifts relative to the halo of up to ∼2000 km s −1 . We interpret these broad, blueshifted components as material in outflow and discuss the kinematical evidence for jet-driven outflows as previously proposed for PKS 1549−79 and PKS 1345+12. Comparisons with samples in the literature show that compact radio sources harbour more extreme nuclear kinematics than their extended counterparts, a trend seen within our sample with larger velocities in the smaller sources. The observed velocities are also likely to be influenced by source orientation with respect to the observer's line of sight. Nine sources have associated H I absorption. In common with the optical emission-line gas, the H I profiles are often highly complex with the majority of the detected components significantly blueshifted, tracing outflows in the neutral gas. The sample has been tested for stratification in the ISM (FWHM/ionization potential/critical density) as suggested by Holt, Tadhunter & Morganti for PKS 1345+12 but we find no significant trends within the sample using a Spearman rank analysis. This study supports the idea that compact radio sources are young radio-loud active galactic nuclei observed during the early stages of their evolution and currently shedding their natal cocoons through extreme circumnuclear outflows.

We present intermediate resolution, large wavelength coverage spectra for the compact radio source PKS 1345+12 (4C 12.50, z = 0.122) that were taken with the aim of investigating the impact of the nuclear activity on the circumnuclear interstellar medium (ISM). Our spectra show extended line emission up to ∼20 kpc from the nucleus, consistent with the asymmetric halo of diffuse emission observed in optical and infrared images. At the position of the nucleus we observe complex emission line profiles and Gaussian fits to the [O III] emission lines require three components (narrow, intermediate and broad), the broadest of which has width ∼2000 km s −1 (FWHM) and is blueshifted by ∼2000 km s −1 with respect to the halo of the galaxy and H I absorption. We interpret this latter component as material in outflow. We also find evidence for large reddening [0.92 < E(B − V ) < 2.00] and high densities (n e > 4200 cm −3 ) for the most kinematically disturbed component. The corresponding total mass of line-emitting gas in the kinematically disturbed components is M gas < 10 6 M . Not all emission line profiles can be reproduced by the same model: [O I]λλ6300, 6363 and [S II]λλ6716, 6731 require separate, unique models. We argue that PKS 1345+12 is a young radio source with nuclear regions that are enshrouded in a dense cocoon of gas and dust. The radio jets are expanding through this cocoon, sweeping material out of the nuclear regions. Emission originates from three kinematically distinct regions, though gradients (e.g. in density, ionization potential, velocity) must exist across the regions responsible for the emission of the intermediate and broad components. C 2003 RAS 1 H 0 = 75 km s −1 , q 0 = 0.0 assumed throughout, resulting in a scale of 2.37 kpc arcsec −1 at z = 0.122. 2 S ∝ ν −α assumed throughout.

We use deep optical, infrared and radio observations to explore the symbiosis between nuclear activity and galaxy evolution in the southern compact radio source PKS 1549−79 (z= 0.1523). The optical imaging observations reveal the presence of tidal tail features which provide strong evidence that the host galaxy has undergone a major merger in the recent past. The merger hypothesis is further supported by the detection of a young stellar population (YSP), which, on the basis of spectral synthesis modelling of our deep Very Large Telescope (VLT) optical spectra, was formed 50–250 Myr ago and makes up a significant fraction of the total stellar mass (1–30 per cent). Despite the core‐jet structure of the radio source, which is consistent with the idea that the jet is pointing close to our line of sight, our H i 21‐cm observations reveal significant H i absorption associated with both the core and the jet. Moreover, the luminous, quasar‐like active galactic nucleus (AGN) (MV < −23.5) is highly extinguished (Av > 6.4) at optical wavelengths and show many properties in common with narrow‐line Seyfert 1 galaxies (NLS1), including relatively narrow permitted lines [full width at half‐maximum (FWHM) ∼ 1940 km s−1], highly blueshifted [O iii]λλ5007,4959 lines (ΔV∼ 680 km s−1) and evidence that the putative supermassive black hole is accreting at a high Eddington ratio (0.3 < Lbol/Ledd < 11). The results suggest that accretion at high Eddington ratio does not prevent the formation of powerful relativistic jets. Together, the observations lend strong support to the predictions of some recent numerical simulations of galaxy mergers in which the black hole grows rapidly through merger‐induced accretion following the coalescence of the nuclei of two merging galaxies, and the major growth phase is largely hidden at optical wavelengths by the natal gas and dust. Although the models also predict that AGN‐driven outflows will eventually remove the gas from the bulge of the host galaxy, the visible warm outflow in PKS 1549−79 is not currently capable of doing so. However, much of the outflow may be hidden by the material obscuring the quasar and/or tied up in hotter or cooler phases of the interstellar medium. By combining our estimates of the reddening of the quasar with the H i column derived from the 21‐cm radio observations, we have also made the first direct estimate of the H i spin temperature in the vicinity of a luminous AGN: Tspin > 3000 K.

We present new ATCA 17-and 24-GHz radio images and ESO-NTT optical spectra of the radio-loud Seyfert galaxy IC 5063, the first galaxy in which a fast (∼600 km s −1 ) outflow of neutral hydrogen was discovered. The new radio data confirm the triple radio structure with a central, unresolved flat-spectrum core and two resolved radio lobes with steep spectral index. This implies that the previously detected fast outflow of neutral gas is occurring off-nucleus, near a radio lobe about 0.5 kpc from the core. The ionised gas shows highly complex kinematics in the region co-spatial with the radio emission. Broad and blueshifted (∼500 km s −1 ) emission is observed in the region of the radio lobe, at the same location as the blueshifted H i absorption. The velocity of the ionised outflow is similar to the one found in H i. The first order correspondence between the radio and optical properties suggests that the outflow is driven by the interaction between the radio jet and the ISM. However, despite the high outflow velocities, no evidence is found for the ionisation of the gas being due to fast shocks in the region of the outflow, indicating that photoionisation from the AGN is likely to be the dominant ionisation mechanism. The outflow rate of the warm (ionised) gas is small compared to that of the cold gas, similar to what is found in other radio galaxies.The mass outflow rate associated with the H i is in the same range as for "mild" starburst-driven superwinds in ULIRGs. However, in IC 5063, the AGN-driven outflow appears to be limited to the inner kpc region of the galaxy. The kinetic power associated with the H i outflow is a small fraction (a few ×10 −4 ) of the Eddington luminosity of the galaxy but is a significant fraction (∼0.1) of the nuclear bolometric luminosity. In IC 5063, the observed outflows may have sufficient kinetic power to have a significant impact on the evolution of the ISM in the host galaxy.