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Abstract Abundance measurements for the volatile element phosphorus are important for measuring the metallicity in interstellar and circumgalactic gas, where their accuracies are limited by uncertainties in the oscillator strengths. We report updated oscillator strength values for two resonant transitions of the dominant ion PII, the transitions at 961.041 and 963.801 Å, which have historically shown large uncertainties. Using a combination of observational measurements and highly accurate quasi-relativistic Hartree–Fock theoretical calculations, we present an updated oscillator strength off= 0.147 ± 0.021 for the poorly constrained PIIresonant transition at 961.401 Å, which arises from the ground electronic state 3s²3p²³P₀to the excited level 3s²3p3d³D ${}_1^{\mathrm{o}}$. This result utilizes archival optical spectra obtained with the Very Large Telescope for the quasar PKS 0528–250, which has a damped Lyαabsorber atz= 2.811. We calculate a theoreticalf-value = 0.153 for 961.401 Å consistent with our empirically derived value, and calculate a theoreticalf-value = 1.79 for 963.801 Å. We also present theoretical oscillator strengths for the PIIresonant transitions at 972.779, 1124.945, 1152.818, 1301.874, and 1532.533 Å, as well as for multiple PIIfine-structure and excited-level transitions. The updatedf-value for the PII961 Å transition will be useful in future studies of P abundances, especially in sight lines where the 1152 Å line is saturated. 

ABSTRACT The flow of gas into and out of galaxies leaves traces in the circumgalactic medium which can then be studied using absorption lines towards background quasars. We analyse 27 $${{\log [N({\textrm {H}}\, {\small {I}})/\rm {cm}^{-2}]}} > 18.0$$ H i absorbers at z = 0.2 to 1.4 from the MUSE-ALMA Haloes survey with at least one galaxy counterpart within a line of sight velocity of ±500 km s−1. We perform 3D kinematic forward modelling of these associated galaxies to examine the flow of dense, neutral gas in the circumgalactic medium. From the VLT/MUSE, HST broad-band imaging, and VLT/UVES and Keck/HIRES high-resolution UV quasar spectroscopy observations, we compare the impact parameters, star-formation rates, and stellar masses of the associated galaxies with the absorber properties. We find marginal evidence for a bimodal distribution in azimuthal angles for strong H i absorbers, similar to previous studies of the Mg ii and O vi absorption lines. There is no clear metallicity dependence on azimuthal angle, and we suggest a larger sample of absorbers is required to fully test the relationship predicted by cosmological hydrodynamical simulations. A case-by-case study of the absorbers reveals that ten per cent of absorbers are consistent with gas accretion, up to 30 per cent trace outflows, and the remainder trace gas in the galaxy disc, the intragroup medium, and low-mass galaxies below the MUSE detection limit. Our results highlight that the baryon cycle directly affects the dense neutral gas required for star-formation and plays a critical role in galaxy evolution. 

Abstract Abundances of chemical elements in the interstellar and circumgalactic media of high-redshift galaxies offer important constraints on the nucleosynthesis by early generations of stars. Damped Lyαabsorbers (DLAs) in spectra of high-redshift background quasars are excellent sites for obtaining robust measurements of element abundances in distant galaxies. Past studies of DLAs at redshiftsz> 4 have measured abundances of ≲0.01 solar. Here we report the discovery of a DLA atz= 4.7372 with an exceptionally high degree of chemical enrichment. We estimate the Hicolumn density in this absorber to be log (N_{H I}/cm⁻²) = 20.48 ± 0.15. Our analysis shows unusually high abundances of carbon and oxygen ([C/H] = 0.88 ± 0.17, [O/H] = 0.71 ± 0.16). Such a high level of enrichment a mere 1.2 Gyr after the Big Bang is surprising because of insufficient time for the required amount of star formation. To our knowledge, this is the first supersolar absorber found atz> 4.5. We find the abundances of Si and Mg to be [Si/H] = $-{0.56}_{-0.35}^{+0.40}$and [Mg/H] = ${0.59}_{-0.50}^{+0.27}$, confirming the metal-rich nature of this absorber. By contrast, Fe shows a much lower abundance ([Fe/H] = $-{1.53}_{-0.15}^{+0.15}$). We discuss implications of our results for galactic chemical evolution models. The metallicity of this absorber is higher than that of any other known DLA and is >2 orders of magnitude above predictions of chemical evolution models and theN_{H I}-weighted mean metallicity from previous studies atz> 4.5. The relative abundances (e.g., [O/Fe] = 2.29 ± 0.05, [C/Fe] = 2.46 ± 0.08) are also highly unusual compared to predictions for enrichment by early stars. 

ABSTRACT The distribution of gas and metals in the circumgalactic medium (CGM) plays a critical role in how galaxies evolve. The MUSE-ALMA Haloes survey combines MUSE, ALMA, and HST observations to constrain the properties of the multiphase gas in the CGM and the galaxies associated with the gas probed in absorption. In this paper, we analyse the properties of galaxies associated with 32 strong $${\rm H\, {\small I}}$$ Ly-α absorbers at redshift 0.2 ≲ z ≲ 1.4. We detect 79 galaxies within ±500 kms−1 of the absorbers in our 19 MUSE fields. These associated galaxies are found at physical distances from 5.7 kpc and reach star formation rates as low as 0.1 M⊙ yr−1. The significant number of associated galaxies allows us to map their physical distribution on the Δv and b plane. Building on previous studies, we examine the physical and nebular properties of these associated galaxies and find the following: (i) 27/32 absorbers have galaxy counterparts and more than 50 per cent of the absorbers have two or more associated galaxies, (ii) the $${\rm H\, {\small I}}$$ column density of absorbers is anticorrelated with the impact parameter (scaled by virial radius) of the nearest galaxy as expected from simulations, (iii) the metallicity of associated galaxies is typically larger than the absorber metallicity, which decreases at larger impact parameters. It becomes clear that while strong $${\rm H\, {\small I}}$$ absorbers are typically associated with more than a single galaxy, we can use them to statistically map the gas and metal distribution in the CGM. 

A powerful technique to trace the signatures of the first stars is through the metal enrichment in concentrated reservoirs of hydrogen, such as the damped Lyα absorbers (DLAs) in the early Universe. We conducted a survey aimed at discovering DLAs along sight lines to high-z quasars in order to measure element abundances at z > 4. Here we report our first results from this survey for 10 DLAs with redshifts of ≈4.2–5.0. We determine abundances of C, O, Si, S, and Fe, and thereby the metallicities and dust depletions. We find that DLA metallicities at z > 4.5 show a wide diversity spanning ∼3 orders of magnitude. The metallicities of DLAs at 3.7 < z < 5.3 show a larger dispersion compared to that at lower redshifts. Combining our sample with the literature, we find a relatively smooth evolution of metallicity with redshift out to z ∼ 5.3, with a tentative (∼2 sigma) indication of a slight rise in metallicity at 4.5 < z < 5.3. The relative abundances exhibit C enhancement for both metal-poor and metal-enriched DLAs. In addition, α-element enhancement is evident in some DLAs, including a DLA at z = 4.7 with a supersolar metallicity. Comparing [C/O] and [Si/O] with model predictions, four DLAs in our survey seem consistent with a nonzero Population III contribution (three with >~30% Population III contribution). Combining our sample and the literature, we find the dust depletion strength and dust-to-metal ratios to correlate positively with the total (gas+solid phase) metallicity, confirming the presence of metal-rich, dusty DLAs even at ∼1 billion years after the Big Bang. 

Abundances of chemical elements in the interstellar and circumgalactic media of high-redshift galaxies offer important constraints on the nucleosynthesis by early generations of stars. Damped Lyα absorbers (DLAs) in spectra of high-redshift background quasars are excellent sites for obtaining robust measurements of element abundances in distant galaxies. Past studies of DLAs at redshifts z > 4 have measured abundances of 0.01 solar. Here we report the discovery of a DLA at z = 4.7372 with an exceptionally high degree of chemical enrichment. We estimate the H I column density in this absorber to be log (NH I/cm^−2) = 20.48 ± 0.15. Our analysis shows unusually high abundances of carbon and oxygen ([C/H] = 0.88 ± 0.17, [O/H] = 0.71 ± 0.16). Such a high level of enrichment a mere 1.2 Gyr after the Big Bang is surprising because of insufficient time for the required amount of star formation. To our knowledge, this is the first supersolar absorber found at z > 4.5. We find the abundances of Si and Mg to be [Si/H] = -0.56-0.35+0.40 and [Mg/H] = -0.59-0.50+0.27, confirming the metal-rich nature of this absorber. By contrast, Fe shows a much lower abundance ([Fe/H] = -1.53 ± 0.15). We discuss implications of our results for galactic chemical evolution models. The metallicity of this absorber is higher than that of any other known DLA and is >2 orders of magnitude above predictions of chemical evolution models and the NH I-weighted mean metallicity from previous studies at z > 4.5. The relative abundances (e.g., [O/Fe] = 2.29 ± 0.05, [C/Fe] = 2.46 ± 0.08) are also highly unusual compared to predictions for enrichment by early stars. 

Abstract We report Hubble Space Telescope Cosmic Origins Spectrograph spectroscopy of 10 quasars with foreground star-forming galaxies at 0.02 < z < 0.14 within impact parameters of ∼1–7 kpc. We detect damped/sub-damped Ly α (DLA/sub-DLA) absorption in 100% of cases where no higher-redshift Lyman-limit systems extinguish the flux at the expected wavelength of Ly α absorption, obtaining the largest targeted sample of DLA/sub-DLAs in low-redshift galaxies. We present absorption measurements of neutral hydrogen and metals. Additionally, we present Green Bank Telescope 21 cm emission measurements for five of the galaxies (including two detections). Combining our sample with the literature, we construct a sample of 117 galaxies associated with DLA/sub-DLAs spanning 0 < z < 4.4, and examine trends between gas and stellar properties, and with redshift. The H i column density is anticorrelated with impact parameter and stellar mass. More massive galaxies appear to have gas-rich regions out to larger distances. The specific star formation rate (sSFR) of absorbing galaxies increases with redshift and decreases with M *, consistent with evolution of the star formation main sequence (SFMS). However, ∼20% of absorbing galaxies lie below the SFMS, indicating that some DLA/sub-DLAs trace galaxies with longer-than-typical gas-depletion timescales. Most DLA/sub-DLA galaxies with 21 cm emission have higher H i masses than typical galaxies with comparable M *. High M HI / M * ratios and high sSFRs in DLA/sub-DLA galaxies with M * < 10 9 M ⊙ suggest these galaxies may be gas-rich because of recent gas accretion rather than inefficient star formation. Our study demonstrates the power of absorption and emission studies of DLA/sub-DLA galaxies for extending galactic evolution studies to previously under-explored regimes of low M * and low SFR. 

ABSTRACT We present abundance measurements of the elements Zn, S, O, C, Si, and Fe for four sub-DLAs at redshifts ranging from z = 2.173 to 2.635 using observations from the MIKE spectrograph on the Magellan telescope to constrain the chemical enrichment and star formation of gas-rich galaxies. Using weakly depleted elements O, S, and or Zn, we find the metallicities after the photoionization corrections to be [S/H] = −0.50 ± 0.11, [O/H] > −0.84, [O/H] = −1.27 ± 0.12, and [Zn/H]  = +0.40 ± 0.12 for the absorbers at z  = 2.173, 2.236, 2.539, and 2.635, respectively. Moreover, we are able to put constraints on the electron densities using the fine structure lines of C ii⋆ and Si ii⋆ for two of the sub-DLAs. We find that these values are much higher than the median values found in DLAs in the literature. Furthermore, we estimate the cooling rate lc = 1.20 × 10−26 erg s−1 per H atom for an absorber at z = 2.173, suggesting higher star formation rate density in this sub-DLA than the typical star formation rate density for DLAs at similar redshifts. We also study the metallicity versus velocity dispersion relation for our absorbers. Most of the absorbers follow the trend one can expect from the mass versus metallicity relation for sub-DLAs in the literature. Finally, we are able to put limits on the molecular column density from the non-detections of various strong lines of CO molecules. We estimate 3σ upper limits of logN(CO, J = 0) < 13.87, logN(CO, J = 0) < 13.17, and logN(CO, J = 0) < 13.08, respectively, from the non-detections of absorption from the J = 0 level in the CO AX 0–0, 1–0, and 2–0 bands near 1544, 1510, and 1478 Å.