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Outflowing winds of multiphase plasma have been proposed to regulate the buildup of galaxies, but key aspects of these outflows have not been probed with observations. By using ultraviolet absorption spectroscopy, we show that "warm-hot" plasma at 105.5 kelvin contains 10 to 150 times more mass than the cold gas in a post-starburst galaxy wind. This wind extends to distances > 68 kilopersecs, and at least some portion of it wit[ escape. Moreover, the kinematical correlation of the cold and warm-hot phases indicates that the warm-hot plasma is related to the interaction of the cold matter with a hotter (unseen) phase at >>106 kelvin. Such multiphase winds can remove substantial masses and alter the evolution of post-starburst galaxies. [ABSTRACT FROM AUTHOR]

We present deep ground based imaging of the environments of five quasi-stellar objects (QSOs) that contain sub-damped Lyman α (sub-DLA) systems at with the Southern Observatories Astrophysics Research (SOAR) telescope and SOAR Optical Imager (SOI) camera. We detect a clear surplus of galaxies in these small fields, supporting the assumption that we are detecting the galaxies responsible for the absorption systems. Assuming these galaxies are at the redshift of the absorption line systems, we detect luminous galaxies for four of the five fields within 10 arcsec of the QSO. In contrast to previous imaging surveys of DLA systems at these redshifts, which indicate a range of morphological types and luminosities for the host galaxies of the systems, the galaxies we detect in these sub-DLA fields appear to be luminous (). In the case of the absorber towards Q0026 at we have spectroscopic confirmation that the candidate galaxy is at the redshift of the absorber, at an impact parameter of ∼35 kpc with a luminosity of depending on the magnitude of the K-correction. These observations are in concordance with the view that sub-DLA systems may be more representative of massive galaxies than DLA systems. The environments of the absorbers span a range of types, from the inner disc of a galaxy, the periphery of a luminous galaxy and the outskirts of interacting galaxies. The large impact parameters to some of the candidate galaxies suggest that galactic outflows or tidal tails are likely responsible for the material seen in absorption. We find a weak correlation between and the impact parameter at the 2σ level, which may be expected from the heterogeneous population of galaxies hosting the absorption line systems and random orientation angles. In addition, we detect a possible gravitationally lensed image of the BL-Lac object Q2230. [ABSTRACT FROM AUTHOR]

We have combined the results from our recent observations of damped and sub-damped Lyman α (sub-DLA) systems with the Magellan Inamori Kyocera Echelle and Ultraviolet Visual Echelle Spectrograph on the Magellan Clay and Very Large Telescopes with ones from the literature to determine the -weighted mean metallicity of these systems based both on Fe, a depleted element in quasi-stellar object absorbers and the local interstellar medium, and Zn a relatively undepleted element. In each case, the -weighted mean metallicity is higher and shows faster evolution in sub-DLAs than the classical DLA systems. Large grids of photoionization models over the sub-DLA range withcloudy show that the ionization corrections to the abundances are in general small, however the fraction of ionized H can be up to ∼90 per cent. The individual spectra have been shifted to the rest frame of the absorber and averaged together to determine the average properties of these systems at . We find that the average abundance pattern of the sub-DLA systems is similar to the gas in the halo of the Milky Way, with an offset of ∼0.3 dex in the overall metallicity. Both DLAs and sub-DLAs show similar characteristics in their relative abundances patterns, although the DLAs have smaller 〈[Mn/Zn]〉 as well as higher 〈[Ti/Zn]〉 and 〈[Cr/Zn]〉. We calculate the contribution of sub-DLAs to the metal budget of the Universe, and find that the sub-DLA systems at contain a comoving density of metals , at least twice the comoving density of metals in the DLA systems. The sub-DLAs do, however, track global chemical evolution models much more closely than do the DLAs, perhaps indicating that they are a less dust biased metallicity indicator of galaxies at high redshifts than the DLA systems. [ABSTRACT FROM AUTHOR]

The damped Lyman α (DLA) and sub-damped Lyman α (sub-DLA) systems seen in the spectra of quasi-stellar objects (QSOs) offer a unique way to study the interstellar medium (ISM) of high-redshift galaxies. In this paper, we report on new abundance determinations in a sample of 10 new systems, nine of the lesser studied sub-DLAs and one DLA along the line of sight to seven QSOs from spectra taken with the Magellan Inamori Kyocera Echelle spectrograph. Lines of Mg i, Mg ii, Al ii, Al iii, Ca ii, Mn ii, Fe ii and Zn ii were detected. Here, we give the column densities and equivalent widths of the observed absorption lines, as well as the abundances determined for these systems. Zn, a relatively undepleted element in the local ISM is detected in one system with a high metallicity of . In another system, a high abundance based on the more depleted element Fe is seen with , although Zn is not detected. The -weighted mean metallicity of these sub-DLA systems based on Fe is , nearly ∼0.7 dex higher (a factor of 5) than what is seen in DLAs in this redshift range. The relative abundance of [Mn/Fe] is also investigated. A clear trend is visible for these systems as well as systems from the literature, with [Mn/Fe] increasing with increasing metallicity in good agreement with Milky Way stellar abundances. [ABSTRACT FROM AUTHOR]

We present chemical abundance measurements from medium-resolution observations of eight subdamped Lyα (sub-DLA) absorber and two strong Lyman-limit systems at observed with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the 6.5-m Magellan II Clay telescope. These observations were taken as part of an ongoing project to determine abundances in quasar absorption line systems focusing on sub-DLA systems. These observations increase the sample of Zn measurements in sub-DLAs by ∼50 per cent. Lines of Mg i, Mg ii, Al ii, Al iii, Ca ii, Mn ii, Fe ii and Zn ii were detected and column densities were determined. Zn ii, a relatively undepleted element and tracer of the gas-phase metallicity is detected in two of these systems, with and . The latter one is however a weak system with , and therefore may need significant ionization corrections to the abundances. Fe ii lines were detected in all systems, with an average Fe abundance of , higher than typical Fe abundances for DLA systems at these redshifts. This high mean [Fe/H] could be due to less depletion of Fe on to dust grains, or to higher abundances in these systems. We also discuss the relative abundances in these absorbers. The systems with high metallicity show high ratios of [Mn/Fe] and [Zn/Fe], as seen previously in another sub-DLA. These higher values of [Mn/Fe] could be a result of heavy depletion of Fe on to grains, unmixed gas, or an intrinsically non-solar abundance pattern. Based oncloudy modelling, we do not expect ionization effects to cause this phenomenon. [ABSTRACT FROM AUTHOR]

We present chemical abundance measurements from high-resolution observations of seven subdamped Lyα (sub-DLA) absorbers and one DLA system at . Three of these objects have high metallicity, with near or supersolar Zn abundance. Grids ofcloudy models for each system were constructed to look for possible ionization effects in these systems. For the systems in which we could constrain the ionization parameter, we find that the ionization corrections as predicted by thecloudy models are generally small and within the typical error bars (∼0.15 dex), in general agreement with previous studies. The Al iii to Al ii ratio for these and other absorbers from the literature are compared, and we find that while the sub-DLAs have a larger scatter in the Al iii to Al ii ratios than the DLAs, there appears to be little correlation between the ratio and . The relationship between the metallicity and the velocity width of the profile for these systems is investigated. We show that the sub-DLAs that have been observed to date follow a similar trend as DLA absorbers, with the more metal rich systems exhibiting large velocity widths. We also find that the systems at the upper edge of this relationship with high metallicities and large velocity widths are more likely to be sub-DLAs than DLA absorbers, perhaps implying that the sub-DLA absorbers are more representative of massive galaxies. [ABSTRACT FROM AUTHOR]

We present elemental abundance measurements for nine damped Lyman α (Lyα) systems (DLAs) and one sub-DLA at from recent observations with the Multiple Mirror Telescope (MMT). Most of these absorbers are found to be metal poor, while two are found to have ≈30–50 per cent solar metallicities. Combining our data with other data from the literature, we find that the systems with higher [Zn/H] also have stronger depletion as measured by [Cr/Zn] and [Fe/Zn]. The relationship between the metallicity and H i column density is also investigated. Together with our previous MMT survey, we have discovered two of the four known absorbers at that lie above (although near) the ‘obscuration threshold’. This appears to be a result of selecting absorbers with strong metal lines in our sample. It would be interesting to find other similar systems by observing a larger sample and study how much such systems contribute to the cosmic budget of metals. Finally, an analysis of the NH i-weighted mean metallicity versus redshift for our sample combined with data from the literature supports previous conclusions that the NH i-weighted mean global DLA metallicity rises slowly at best and falls short of solar levels by a factor of >4 even at z= 0. [ABSTRACT FROM AUTHOR]

We present the design and methods of the COS-Halos survey, a systematic investigation of the gaseous halos of 44 z = 0.15-0.35 galaxies using background QSOs observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope. This survey has yielded 39 spectra of zem ≃ 0.5 QSOs with S/N ∼10-15 per resolution element. The QSO sightlines pass within 150 physical kpc of the galaxies, which span early and late types over stellar mass log M*/M☼ = 9.5-11.5. We find that the circumgalactic medium exhibits strong H I, averaging ≃ 1 Å in Lyα equivalent width out to 150 kpc, with 100% covering fraction for star-forming galaxies and 75% covering for passive galaxies. We find good agreement in column densities between this survey and previous studies over similar range of impact parameter. There is weak evidence for a difference between early- and late-type galaxies in the strength and distribution of H I. Kinematics indicate that the detected material is bound to the host galaxy, such that ≳ 90% of the detected column density is confined within ±200 km s–1 of the galaxies. This material generally exists well below the halo virial temperatures at T ≲ 105 K. We evaluate a number of possible origin scenarios for the detected material, and in the end favor a simple model in which the bulk of the detected H I arises in a bound, cool, low-density photoionized diffuse medium that is generic to all L* galaxies and may harbor a total gaseous mass comparable to galactic stellar masses. [ABSTRACT FROM AUTHOR]

We present UV and optical observations from the Cosmic Origins Spectrograph on the Hubble Space Telescope and Keck of a z = 0.27395 Lyman limit system (LLS) seen in absorption against the QSO PG1630+377. We detect H I absorption with log N(H I) = 17.06 ± 0.05 as well as Mg II, C III, Si III, and O VI in this system. The column densities are readily explained if this is a multi-phase system, with the intermediate and low ions arising in a very low metallicity ([Mg/H] = -1.71 ± 0.06) photoionized gas. We identify via Keck spectroscopy and Large Binocular Telescope imaging a 0.3 L* star-forming galaxy projected 37 kpc from the QSO at nearly identical redshift (z = 0.27406 and Δv = -26 km s-1) with near solar metallicity ([O/H] = -0.20 ± 0.15). The presence of very low metallicity gas in the proximity of a near-solar metallicity, sub-L* galaxy strongly suggests that the LLS probes gas infalling onto the galaxy. A search of the literature reveals that such low-metallicity LLSs are not uncommon. We found that 50% (4/8) of the well-studied z ≲ 1 LLSs have metallicities similar to the present system and show sub-L* galaxies with ρ < 100 kpc in those fields where redshifts have been surveyed. We argue that the properties of these primitive LLSs and their host galaxies are consistent with those of cold mode accretion streams seen in galaxy simulations. [ABSTRACT FROM AUTHOR]