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We present analysis of the mass-metallicity relation (MZR) for a sample of 67 [O III]-selected star-forming (SF) galaxies at a redshift range of z = 1.99-2.32 ( z med = 2.16) using Hubble Space Telescope Wide Field Camera 3 grism spectroscopy from the Quasar Sightline and Galaxy Evolution survey. Metallicities were determined using empirical gas-phase metallicity calibrations based on the strong emission lines [O II]3727, 3729, [O III]4959, 5007 and H beta. SF galaxies were identified, and distinguished from active-galactic nuclei, via Mass-Excitation diagrams. Using z 0 metallicity calibrations, we observe a negative offset in the z = 2.2 MZR of -0.51 dex in metallicity when compared to locally derived relationships, in agreement with previous literature analysis. A similar offset of -0.46 dex in metallicity is found when using empirical metallicity calibrations that are suitable out to z 5, though our z = 2.2 MZR, in this case, has a shallower slope. We find agreement between our MZR and those predicted from various galaxy evolution models and simulations. Additionally, we explore the extended fundamental metallicity relation (FMR) which includes an additional dependence on star formation rate. Our results consistently support the existence of the FMR, as well as revealing an offset of 0.28 +/- 0.04 dex in metallicity compared to locally derived relationships, consistent with previous studies at similar redshifts. We interpret the negative correlation with SFR at fixed mass, inferred from an FMR existing for our sample, as being caused by the efficient accretion of metal-poor gas fuelling SFR at cosmic noon.

We present a study of the metal-enriched halo gas, traced using Mg II and [O II] emission lines, in two large, blind galaxy surveys – the MUSE (Multi Unit Spectroscopic Explorer) Analysis of Gas around Galaxies (MAGG) and the MUSE Ultra Deep Field (MUDF). By stacking a sample of ≈600 galaxies (stellar masses M∗ ≈ 106–12 M☉), we characterize for the first time the average metal line emission from a general population of galaxy haloes at 0.7 ≤ z ≤ 1.5. The Mg II and [O II] line emission extends farther out than the stellar continuum emission, on average out to ≈25 and ≈45 kpc, respectively, at a surface brightness (SB) level of 10-20 erg s-1 cm-2 arcsec-2. The radial profile of the Mg II SB is shallower than that of the [O II], suggesting that the resonant Mg II emission is affected by dust and radiative transfer effects. The [O II] to Mg II SB ratio is ≈3 over ≈20–40 kpc, also indicating a significant in situ origin of the extended metal emission. The average SB profiles are intrinsically brighter by a factor of ≈2–3 and more radially extended by a factor of ≈1.3 at 1.0 < z ≤ 1.5 than at 0.7 ≤ z ≤ 1.0. The average extent of the metal emission also increases independently with increasing stellar mass and in overdense group environments. When considering individual detections, we find extended [O II] emission up to ≈50 kpc around ≈30–40 per cent of the group galaxies, and extended (≈30–40 kpc) Mg II emission around two z ≈ 1 quasars in groups, which could arise from outflows or environmental processes.

We present a study of metal-enriched halo gas traced by Mg ii and C iv absorption at z < 2 in the MUSE Analysis of Gas around Galaxies survey and the Quasar Sightline and Galaxy Evolution survey. Using these large and complete galaxy surveys in quasar fields, we study the dependence of the metal distribution on galaxy properties and overdensities, out to physical projected separations of 750 kpc. We find that the cool, low-ionization gas is significantly affected by the environment across the full redshift range probed, with ≈2-3 times more prevalent and stronger Mg ii absorption in higher overdensity group environments and in regions with greater overall stellar mass and star formation rates. Complementary to these results, we have further investigated the more highly ionized gas as traced by C iv absorption, and found that it is likely to be more extended than the Mg ii gas, with ≈2 times higher covering fraction at a given distance. We find that the strength and covering fraction of C iv absorption show less significant dependence on galaxy properties and environment than the Mg ii absorption, but more massive and star-forming galaxies nevertheless also show ≈2 times higher incidence of C iv absorption. The incidence of Mg ii and C iv absorption within the virial radius shows a tentative increase with redshift, being higher by a factor of ≈1.5 and ≈4, respectively, at z > 1. It is clear from our results that environmental processes have a significant impact on the distribution of metals around galaxies and need to be fully accounted for when analysing correlations between gaseous haloes and galaxy properties.

Recently,Carnall et al. discovered two bright high-redshift quasars using the combination of the Very Large Telescope (VLT) Survey Telescope (VST) ATLAS and Wide-field Infrared Survey Explorer (WISE) surveys. The technique involved using the 3D colour plane i-z: z-W1: W1- W2with the WISEW1 (3.4 micron) andW2 (4.5 micron) bands taking the place of the usual NIR J band to help decrease stellar dwarf contamination. Here, we report on our continued search for 5.7 < z < 6.4 quasars over an ≈ 2×larger area of≈3577 deg2 of the Southern Hemisphere. We have found two further z > 6 quasars, VST-ATLAS J158.6938-14.4211 at z = 6.07 and J332.8017-32.1036 at z = 6.32 with magnitudes of zAB = 19.4 and 19.7 mag, respectively. J158.6938-14.4211 was confirmed by Keck LRIS observations and J332.8017-32.1036 was confirmed by ESO NTT EFOSC-2 observations. Here, we present VLT X-shooter visible and NIR spectra for the four ATLAS quasars. We have further independently rediscovered two z > 5.7 quasars previously found by the VIKING/KiDS and PanSTARRS surveys. This means that in ATLAS we have now discovered a total of six quasars in our target 5.7 < z < 6.4 redshift range. Making approximate corrections for incompleteness, we find that our quasar space density agrees with the Sloan Digital Sky Survey results of Jiang et al. at M1450Å ≈ -27. Preliminary virial mass estimates based on the C IV and MgII emission lines give black hole masses in the range MBH ≈ 1-6 × 109M⊙ for the four ATLAS quasars

Post-starburst E+A galaxies show indications of a powerful starburst that was quenched abruptly. Their disturbed, bulge-dominated morphologies suggest that they are merger remnants. Themoremassive E+A galaxies are suggested to be quenched by active galactic nucleus (AGN) feedback, yet little is known about AGN-driven winds in this short-lived phase. We present spatially resolved integral field unit spectroscopy by the Keck Cosmic Web Imager of SDSS J003443.68 + 251020.9, at z = 0.118. The system consists of two galaxies, the larger of which is a post-starburst E+A galaxy hosting an AGN. Our modelling suggests a 400 Myr starburst, with a peak star formation rate of 120 M⊙ yr-1. The observations reveal stationary and outflowing gas, photoionized by the central AGN. We detect gas outflows to a distance of 17 kpc from the central galaxy, far beyond the region of the stars (~3 kpc), inside a conic structure with an opening angle of 70 deg. We construct self-consistent photoionization and dynamical models for the different gas components and show that the gas outside the galaxy forms a continuous flow, with a mass outflow rate of about 24 M⊙ yr-1. The gas mass in the flow, roughly 109 M⊙, is larger than the total gas mass within the galaxy, some of which is outflowing too. The continuity of the flow puts a lower limit of 60 Myr on the duration of the AGN feedback. Such AGNs are capable of removing, in a single episode, most of the gas from their host galaxies and expelling enriched material into the surrounding circumgalactic medium.

We demonstrate that the UV brightest quasars at z = 1-2 live in overdense environments. This is based on an analysis of deep Hubble Space Telescope WFC3 G141 grism spectroscopy of the galaxies along the lines-of-sight to UV luminous quasars in the redshift range z = 1-2. This constitutes some of the deepest grism spectroscopy performed by WFC3, with four roll angles spread over a year of observations to mitigate the effect of overlapping spectra. Of the 12 quasar fields studied, 8 display evidence for a galaxy overdensity at the redshift of the quasar. One of the overdensities, PG0117 + 213 at z = 1.50, has potentially 36 spectroscopically confirmed members, consisting of 19 with secure redshifts and 17 with single-line redshifts, within a cylinder of radius similar to 700 kpc. Its halo mass is estimated to be log (M/M-circle dot) = 14.7. This demonstrates that spectroscopic and narrow-band observations around distant UV bright quasars may be an excellent route for discovering protoclusters. Our findings agree with previous hints from statistical observations of the quasar population and theoretical works, as feedback regulated black hole growth predicts a correlation between quasar luminosity and halo mass. We also present the high signal-to-noise rest-frame optical spectral and photometric properties of the quasars themselves.

We study the physical properties of a homogeneous sample of 157 optically thick absorption line systems at redshifts ~1.8-4.4, selected from a high-dispersion spectroscopic survey of Lyman limit systems (LLSs). By means of multiple ionization models and Bayesian techniques, we derive the posterior probability distribution functions for the density, metallicity, temperature and dust content of the absorbing gas.We find that z > 2 LLSs are highly ionized with ionization parameters between -3 ≲ logU ≲ -2, depending on the HI column density. LLSs are characterized by low temperatures (T < 5 × 104K) and reside in dust-poor environments. Between z ~ 2.5-3.5, ~80 per cent of the LLSs have physical densities between nH ~ 10-3.5-10-2 cm-3 for the assumed UV background, but we caution that a degeneracy between the ionization parameter and the intensity of the radiation field prevents robust inference on the density and sizes of LLSs. Conversely, metallicity estimates are less sensitive to the assumptions behind ionization corrections. LLSs at z > 2 are characterized by a broad unimodal distribution over > 4 orders of magnitude, with a peak at log Z/Z⊙ ~-2. LLSs are metal poor, significantly less enriched than DLAs, with ~70 per cent of the metallicity PDF below log Z/Z⊙ = -1.5. The median metallicity of super LLSs with logNHI = 19 rapidly evolves with redshift, with a 10-fold increase between z ~ 2.1-3.6 (~1.5 Gyr). Based on this sample, we find that LLSs at z = 2.5-3.5 account for ~15 per cent of all the metals produced by UV-selected galaxies. The implications for theories of cold gas accretion and metal ejection from galaxies are also discussed.

We report the serendipitous detection of a 0.2 L*, Lya emitting galaxy at redshift 2.5 at an impact parameter of 50 kpc from a bright background QSO sightline. A high-resolution spectrum of the QSO reveals a partial Lyman-limit absorption system (NHI = 1016.94±0.10 cm-2) with many associated metal absorption lines at the same redshift as the foreground galaxy. Using photoionization models that carefully treat measurement errors and marginalize over uncertainties in the shape and normalization of the ionizing radiation spectrum, we derive the total hydrogen column density NH = 1019.4±0.3 cm-2, and show that all the absorbing clouds are metal enriched, with Z = 0.1-0.6 Z⊙. These metallicities and the system's large velocity width (436 km s-1) suggest the gas is produced by an outflowing wind. Using an expanding shell model we estimate a mass outflow rate of ~5M⊙ yr-1. Our photoionization model yields extremely small sizes (<100-500 pc) for the absorbing clouds, which we argue is typical of high column density absorbers in the circumgalactic medium (CGM). Given these small sizes and extreme kinematics, it is unclear how the clumps survive in the CGM without being destroyed by hydrodynamic instabilities. The small cloud sizes imply that even state-of-the-art cosmological simulations require more than a 1000-fold improvement in mass resolution to resolve the hydrodynamics relevant for cool gas in the CGM.

Post-starburst E+A galaxies show indications of a powerful starburst that was quenched abruptly. Their disturbed, bulge-dominated morphologies suggest that they are merger remnants. The more massive E+A galaxies are suggested to be quenched by active galactic nucleus (AGN) feedback, yet little is known about AGN-driven winds in this short-lived phase. We present spatially resolved integral field unit spectroscopy by the Keck Cosmic Web Imager of SDSS J003443.68 + 251020.9, at z = 0.118. The system consists of two galaxies, the larger of which is a post-starburst E+A galaxy hosting an AGN. Our modelling suggests a 400 Myr starburst, with a peak star formation rate of 120 M⊙ yr−1. The observations reveal stationary and outflowing gas, photoionized by the central AGN. We detect gas outflows to a distance of 17 kpc from the central galaxy, far beyond the region of the stars (∼3 kpc), inside a conic structure with an opening angle of 70 deg. We construct self-consistent photoionization and dynamical models for the different gas components and show that the gas outside the galaxy forms a continuous flow, with a mass outflow rate of about 24 M⊙ yr−1. The gas mass in the flow, roughly 109M⊙⁠, is larger than the total gas mass within the galaxy, some of which is outflowing too. The continuity of the flow puts a lower limit of 60 Myr on the duration of the AGN feedback. Such AGNs are capable of removing, in a single episode, most of the gas from their host galaxies and expelling enriched material into the surrounding circumgalactic medium.