We present a detailed study of the kinematic, chemical and excitation properties of the giant Lyα emitting nebula and the giant H i absorber associated with the z = 2.92 radio galaxy MRC 0943-242, using spectroscopic observations from VLT/MUSE, VLT/X-SHOOTER and other instruments. Together, these data provide a wide range of restframe wavelength (765Å -6378Å at z = 2.92) and 2D spatial information. We find clear evidence for jet gas interactions affecting the kinematic properties of the nebula, with evidence for both outflows and inflows being induced by radio-mode feedback. We suggest that the regions of relatively lower ionization level, spatially correlated with the radio hotspots, may be due to localised compression of photoionized gas by the expanding radio source, thereby lowering the ionization parameter, or due to a contribution from shock-heating. We find that photoionization of super-solar metallicity gas (Z/Z = 2.1) by an AGN-like continuum (α=-1.0) at a moderate ionization parameter (U = 0.018) gives the best overall fit to the complete X-SHOOTER emission line spectrum. We identify a strong degeneracy between column density and Doppler parameter such that it is possible to obtain a reasonable fit to the H i absorption feature across the range log N(H i/cm −2 ) = 15.20 and 19.63, with the two best-fitting occurring near the extreme ends of this range. The extended H i absorber is blueshifted relative to the emission line gas, but shows a systematic decrease in blueshift towards larger radii, consistent with a large scale expanding shell.

We study the ultraviolet (UV) emission-line ratios of a sample of 145 type II quasars (QSO2s) from Sloan Digital Sky Survey iii Baryon Oscillation Spectroscopic Survey, and compare against a grid of active galactic nucleus (AGN) photoionization models with a range in gas density, gas chemical abundances, and ionization parameter. Most of the quasars are ‘carbon-loud’, with C  iv/He ii ratios that are unusually high for the narrow-line region, implying higher than expected gas density (>106 cm−3) and/or significantly supersolar-relative carbon abundance. We also find that solar or supersolar nitrogen abundance and metallicity are required in the majority of our sample, with potentially significant variation between objects. Compared to radio galaxies at similar redshifts (HzRGs; z > 2), the QSO2s are offset to higher N  v/He ii, C  iv/He ii, and C iii]/He ii, suggesting systematically higher gas density and/or systematically higher C and N abundances. We find no evidence for a systematic difference in the N/C abundance ratio between the two types of objects. Scatter in the N  iv]/C  iv ratio implies a significant scatter in the N/C abundance ratio among the QSO2s and HzRGs, consistent with differences in the chemical enrichment histories between objects. Interestingly, we find that adopting secondary behaviour for both N and C alleviates the long-standing ‘N  iv] problem’. A subset of the QSO2s and HzRGs also appear to be ‘silicon-loud’, with Si iii] relative fluxes suggesting Si/C and Si/O are an order of magnitude above their solar values. Finally, we propose new UV-line criteria to select genuine QSO2s with low-density narrow-line regions.

We present an investigation of the properties of the extended Lyα halo and the largescale H i absorbing structures associated with 5 high-redshift radio galaxies at z > 2, using the Goodman long-slit spectrograph on the SOAR telescope, with the slit placed at large angles (>45 • ) to the radio axis, to study regions that are unlikely to be illuminated by the active nucleus. Spatially extended Lyα emission is detected with large line widths (FWHM = 1000 -2500 km s −1 ), which although impacted by resonant scattering, is suggestive of turbulent motion. We find a correlation between higher blueshifts and higher FWHM, which is an indication that radial motion dominates the bulk gas dynamics perpendicular to the radio axis, although we are unable to distinguish between outflow and infall scenarios due to the resonant nature of the Lyα line. Extended, blueshifted Lyα absorption is detected in the direction perpendicular to the radio axis in three radio galaxies with minimum spatial extents ranging from > ∼ 27 kpc to > ∼ 35 kpc, supporting the idea that the absorbing structure covers the entire Lyα halo, consistent with being part of a giant, expanding shell of gas enveloping the galaxy and its (detected) gaseous halo.