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Using the Low Dispersion Survey Spectrograph 3 at the Magellan II Clay Telescope, we target candidate absorption host galaxies detected in deep optical imaging (reaching limiting apparent magnitudes of 23.0.26.5 in g, r, i, and z filters) in the fields of three QSOs, each of which shows the presence of high metallicity, high NHI absorption systems in their spectra (Q0826-2230: zabs = 0.9110, Q1323-0021: zabs = 0.7160, Q1436-0051: zabs = 0.7377, 0.9281). We confirm three host galaxies at redshifts 0.7387, 0.7401, and 0.9286 for two of the Lyman α absorption systems (one with two galaxies interacting). For these systems, we are able to determine the star formation rates (SFRs); impact parameters (from previous imaging detections); the velocity shift between the absorption and emission redshifts; and, for one system, also the emission metallicity. Based on previous photometry, we find these galaxies have L > L∗ The [OII] SFRs for these galaxies are in the range 11.25 M⊙ yr-1 (uncorrected for dust), while the impact parameters lie in the range 35.54 kpc. Despite the fact that we have confirmed galaxies at 50 kpc from the QSO, no gradient in metallicity is indicated between the absorption metallicity along the QSO line of sight and the emission line metallicity in the galaxies. We confirm the anticorrelation between impact parameter and NHI from the literature. We also report the emission redshift of five other galaxies: three at zem > zQSO, and two (L < L∗) at zem < zQSO not corresponding to any known absorption systems. [ABSTRACT FROM AUTHOR]

We present photometric and spectroscopic measurements of 53 QSO–galaxy pairs from the Sloan Digital Sky Survey (SDSS), where nebular emission lines from a 0 < z < 0.84 foreground galaxy are detected in the fibre spectra of a background QSO, bringing the overall sample to 103 QSO–galaxy pairs detected in the SDSS. We here study the nature of these systems. Detected foreground galaxies appear at impact parameters between 0.37 and 12.68 kpc. The presence of oxygen and Balmer emission lines allows us to determine the emission line metallicities for our sample, which are on average supersolar in value. Star formation rates for our sample are in the range 0.01–12 M⊙ yr−1. We utilize photometric redshift fitting techniques to estimate the M* values of our galaxies (log M* = 7.34–11.54), and extrapolate this relationship to those galaxies with no imaging detections. Where available, we measure the absorption features present in the QSO spectrum due to the foreground galaxy and the relationships between their rest equivalent widths. We report an anticorrelation between impact parameter and E(B − V)(g − i), as well as a correlation between galaxy colour (u − r) and E(B − V)(g − i). We find that our sample is one of late-type, star-forming galaxies comparable to field galaxies in a similar redshift range, providing important clues to better understand absorption systems. These galaxies represent a sample of typical galaxies in the local Universe for which abundances, extinction, morphology, and absorption properties may be measured using background QSOs with great potential for follow-up observations. [ABSTRACT FROM AUTHOR]

ABSTRACT A search for emission lines in foreground galaxies in quasar spectra ( zgal < zQSO) of the Sloan Digital Sky Survey data release 5 reveals 23 examples of quasars shining through low redshift, foreground galaxies at small impact parameters (<10 kpc). About 74 000 quasar spectra were examined by searching for narrow Hα emission lines at z < 0.38, at a flux level greater than 5 × 10−17 erg cm−2 s−1, and then confirming that other expected emission lines of the H ii regions in the galaxy are detected. The galaxies were deblended from the quasar images to get colours and morphologies. For cases that allow the galaxy and the quasar to be deblended, the galaxies are blue (0.95 < ( u− r) < 1.95). Extinction and reddening through the galaxies are determined from the ( g− i) colour excess of the quasars. These reddening values are compared with the flux ratio of Hα to Hβ, which reflect the extinction for an undetermined fraction of the sightline through each galaxy. No trends were found relating E( B− V)( g− i), impact parameter ( b), and ( u− r) for the galaxies or between E( B− V) derived from ( g− i) and that derived from Hα/Hβ. Comparison with previous studies of quasar absorption systems indicates that our sample is more reddened, suggesting disc-dominated absorber galaxies. Measurement or limits on galactic, interstellar Ca ii and Na i absorption lines are given from the quasar spectrum. No trends were found relating the Ca ii equivalent width W (Ca ii) or the Na i equivalent width W (Na i) to b, but a correlation of rs=−0.77 (α= 0.05) was found relating W (Ca ii) and E( B− V)( g− i). [ABSTRACT FROM AUTHOR]

This paper presents a study of the galactic environment of a chemically pristine (<0.6 per cent solar metallicity) Lyman Limit system (LLS) discovered along the sightline towards QSO SDSSJ 135726.27+043541.4 (⁠|$z$| QSO = 1.233) at projected distance d  = 126 physical kpc (pkpc) from a luminous red galaxy (LRG) at |$z$|  = 0.33. Combining deep Hubble Space Telescope images, MUSE integral field spectroscopic data, and wide-field redshift survey data has enabled an unprecedented, ultradeep view of the environment around this LRG–LLS pair. A total of 12 galaxies, including the LRG, are found at |$d\, \lesssim \, 400$| pkpc and line-of-sight velocity |$\Delta \, v\lt 600$| km s−1 of the LLS, with intrinsic luminosity ranging from |$0.001\, L_*$| to |$2\, L_*$| and a corresponding stellar mass range of |${\rm{M_{\rm star}}}\approx 10^{7-11}\, {\mbox{M$_{\odot }$}}$|⁠. All 12 galaxies contribute to a total mass of |${\rm{M_{\rm star}}}=1.6\times 10^{11}\, {\mbox{M$_{\odot }$}}$| with ≈80 per cent contained in the LRG. The line-of-sight velocity dispersion of these galaxies is found to be σgroup = 230 km s−1 with the centre of mass at d group = 118 pkpc and line-of-sight velocity offset of |$\Delta \, v_{\rm group}=181$| km s−1 from the LLS. Three of these are located at d ≲ 100 pkpc from the LLS, and they are all faint with intrinsic luminosity |$\lt 0.02\, L_*$| and gas-phase metallicity of ≈10 per cent solar in their interstellar medium. The disparity in the chemical enrichment level between the LLS and the group members suggests that the LLS originates in infalling intergalactic medium and that parts of the intergalactic gas near old and massive galaxies can still remain chemically pristine through the not too distant past. [ABSTRACT FROM AUTHOR]

We use medium-resolution Keck/Echellette Spectrograph and Imager spectroscopy of bright quasars to study cool gas traced by Ca ii λλ 3934, 3969 and Na i λλ 5891, 5897 absorption in the interstellar/circumgalactic media of 21 foreground star-forming galaxies at redshifts 0.03 < z < 0.20 with stellar masses 7.4 ≤ log M */ M ⊙ ≤ 10.6. The quasarâ€"galaxy pairs were drawn from a unique sample of Sloan Digital Sky Survey quasar spectra with intervening nebular emission, and thus have exceptionally close impact parameters (R ⊥ < 13 kpc). The strength of this line emission implies that the galaxies’ star formation rates (SFRs) span a broad range, with several lying well above the star-forming sequence. We use Voigt profile modeling to derive column densities and component velocities for each absorber, finding that column densities N (Ca ii) > 1012.5 cmâˆ'2 (N (Na i) > 1012.0 cmâˆ'2) occur with an incidence f C(Ca ii) = 0.63+0.10âˆ'0.11 (f C(Na i) = 0.57+0.10âˆ'0.11). We find no evidence for a dependence of f C or the rest-frame equivalent widths W r (Ca ii K) or W r (Na i 5891) on R ⊥ or M *. Instead, W r (Ca ii K) is correlated with local SFR at >3 σ significance, suggesting that Ca ii traces star formation-driven outflows. While most of the absorbers have velocities within ±50 km sâˆ'1 of the host redshift, their velocity widths (characterized by Î" v 90) are universally 30â€"177 km sâˆ'1 larger than that implied by tilted-ring modeling of the velocities of interstellar material. These kinematics must trace galactic fountain flows and demonstrate that they persist at R ⊥ > 5 kpc. Finally, we assess the relationship between dust reddening and W r (Ca ii K) (W r (Na i 5891)), finding that 33% (24%) of the absorbers are inconsistent with the best-fit Milky Way E (B âˆ'V)- W r relations at >3 σ significance. [ABSTRACT FROM AUTHOR]

We present the first results from a Hubble Space Telescope Wide Field Camera 3/Infrared program, which obtained direct imaging and grism observations of galaxies near quasar sightlines with a high frequency of uncorrelated foreground Mg ii absorption. These highly efficient observations targeted 54 Mg ii absorbers along the line of sight to nine quasars at z(qso ∼ 2. We find that 89% of the absorbers in the range of 0.64 < z < 1.6 can be spectroscopically matched to at least one galaxy with an impact parameter of less than 200 kpc and ∣Δz∣/(1 + z) < 0.006. We have estimated the star formation rates and measured structural parameters for all detected galaxies with impact parameters in the range of 7–200 kpc and star formation rates greater than 1.3 M⊙ yr−1. We find that galaxies associated with Mg ii absorption have significantly higher mean star formation rates and marginally higher mean star formation rate surface densities compared to galaxies with no detected Mg ii. Nearly half of the Mg ii absorbers match more than one galaxy, and the mean equivalent width of the Mg ii absorption is found to be greater for groups, compared to isolated galaxies. Additionally, we observe a significant redshift evolution in the physical extent of Mg ii -absorbing gas around galaxies and evidence of an enhancement of Mg ii within 50° of the minor axis, characteristic of outflows, which persists to 80 kpc around the galaxies, in agreement with recent predictions from simulations. [ABSTRACT FROM AUTHOR]

Galaxy haloes appear to be missing a large fraction of their baryons, most probably hiding in the circumgalactic medium (CGM), a diffuse component within the dark matter halo that extends far from the inner regions of the galaxies. A powerful tool to study the CGM gas is offered by absorption lines in the spectra of background quasars. Here, we present optical (MUSE) and mm (ALMA) observations of the field of the quasar Q1130−1449 which includes a log [ N (H  i)/cm−2] = 21.71 ± 0.07 absorber at z  = 0.313. Ground-based VLT/MUSE 3D spectroscopy shows 11 galaxies at the redshift of the absorber down to a limiting SFR > 0.01 M⊙ yr−1 (covering emission lines of [O  ii ], Hβ, [O  iii ], [N  ii ], and H α), 7 of which are new discoveries. In particular, we report a new emitter with a smaller impact parameter to the quasar line of sight (b  = 10.6 kpc) than the galaxies detected so far. Three of the objects are also detected in CO(1–0) in our ALMA observations indicating long depletion time-scales for the molecular gas and kinematics consistent with the ionized gas. We infer from dedicated numerical cosmological ramses zoom-in simulations that the physical properties of these objects qualitatively resemble a small group environment, possibly part of a filamentary structure. Based on metallicity and velocity arguments, we conclude that the neutral gas traced in absorption is only partly related to these emitting galaxies while a larger fraction is likely the signature of gas with surface brightness almost four orders of magnitude fainter that current detection limits. Together, these findings challenge a picture where strong- |$N(\rm H\,{\small I})$| quasar absorbers are associated with a single bright galaxy and favour a scenario where the H  i gas probed in absorption is related to far more complex galaxy structures. [ABSTRACT FROM AUTHOR]

We present MUSE observations of the field of the quasar Q0152-020, whose spectrum shows a Lyman limit system (LLS) at redshift zabs = 0.38, with a metallicity Z ≾ 0.06 Z⊙ The low-ionization metal lines associated with the LLS present two narrow distinct absorption components with a velocity separation of 26 km s-1. We detect six galaxies within 600 km s-1 from the absorption redshift; their projected distances from the quasar sightline range from 60 to 200 kpc. The optical spectra of five of these galaxies exhibit prominent nebular emission lines, from which we deduce extinction-corrected star formation rates in the range SFR=0.06-1.3M⊙ yr-1, and metallicities between 0.2 Z⊙ and Z⊙. The sixth galaxy is only detected in the stellar continuum. By combining our data with archival Keck/HIRES spectroscopy of the quasar and Hubble Space Telescope/Wide Field Planetary Camera 2 imaging of the field, we can relate absorption line and galaxy kinematics; we conclude that the LLS is most likely associated with the galaxy closest to the quasar sightline (galaxy 'a'). Our morphokinematic analysis of galaxy 'a' combined with the absorption line kinematics supports the interpretation that one of the absorption components originates from an extension of the stellar disk of galaxy 'a', while the other component may arise in accreting gas in a warped disk with specific angular momentum ~3 times larger than the specific angular momentum of the galaxy halo. Such warped disks are common features in hydrodynamical simulations of cold-flow accretion on to galaxies; the data presented here provide observational evidence in favour of this scenario. [ABSTRACT FROM AUTHOR]

We present new Multi Unit Spectroscopic Explorer observations of quasar field Q2131-1207 with a log N(H I) = 19.50 ± 0.15 sub-damped Lyman α at zabs = 0.42980. We detect four galaxies at a redshift consistent with that of the absorber where only one was known before this study. Two of these are star-forming galaxies, while the ones further away from the quasar (>140 kpc) are passive galaxies. We report the metallicities of the H II regions of the closest objects (12 + log(O/H) = 8.98 ± 0.02 and 8.32 ± 0.16) to be higher or equivalent within the errors to the metallicity measured in absorption in the neutral phase of the gas (8.15 ± 0.20). For the closest object, a detailed morphokinematic analysis indicates that it is an inclined large rotating disc with Vmax = 200 ± 3 kms-1. We measure the masses to be Mdyn = 7.4 ± 0.4 × 1010 M⊙ and Mhalo = 2.9 ± 0.2 × 1012 M⊙. Some of the gas seen in absorption is likely to be corotating with the halo of that object, possibly due to a warped disc. The azimuthal angle between the quasar line-of-sight and the projected major axis of the galaxy on the sky is 12°± 1° which indicates that some other fraction of the absorbing gas might be associated with accreting gas. This is further supported by the galaxy to gas metallicity difference. Based on the same arguments, we exclude outflows as a possibility to explain the gas in absorption. The four galaxies form a large structure (at least 200 kpc wide) consistent with a filament or a galaxy group so that a fraction of the absorption could be related to intragroup gas. [ABSTRACT FROM AUTHOR]

We present new MUSE observations of quasar field Q2131-1207 with a log N(H I)=19.50±0.15 sub-DLA at zabs=0.42980. We detect four galaxies at a redshift consistent with that of the absorber where only one was known before this study. Two of these are star forming galaxies, while the ones further away from the quasar (>140 kpc) are passive galaxies. We report the metallicities of the HII regions of the closest objects (12+log(O/H)=8.98±0.02 and 8.32±0.16) to be higher or equivalent within the errors to the metallicity measured in absorption in the neutral phase of the gas (8.15±0.20). For the closest object, a detailed morpho-kinematic analysis indicates that it is an inclined large rotating disk with Vmax=200±3 km s-1. We measure the masses to be Mdyn=7.4±0.4 × 1010 M⊙ and Mhalo=2.9±0.2 × 1012 M⊙. Some of the gas seen in absorption is likely to be co-rotating with the halo of that object, possibly due to a warped disk. The azimuthal angle between the quasar line of sight and the projected major axis of the galaxy on the sky is 12°±1° which indicates that some other fraction of the absorbing gas might be associated with accreting gas. This is further supported by the galaxy to gas metallicity difference. Based on the same arguments, we exclude outflows as a possibility to explain the gas in absorption. The four galaxies form a large structure (at least 200 kpc wide) consistent with a filament or a galaxy group so that a fraction of the absorption could be related to intra-group gas. [ABSTRACT FROM AUTHOR]

The use of background quasars provides a powerful tool to probe the cool gas in the circumgalactic medium of foreground galaxies. Here, we present new observations with SINFONI and X-Shooter of absorbing-galaxy candidates at z = 0.7-1. We report the detection with both instruments of the Hα emission line of one sub-damped Lyman α (sub-DLA) at zabs = 0.941 87 with logN(H I) = 19.38+0.10 -0.15 towards SDSS J002133.27+004300.9.We estimate the star formation rate: SFR = 3.6 ± 2.2 M☉ yr-1 in that system. A detailed kinematic study indicates a dynamical mass Mdyn = 109.9±0.4 M☉ and a halo mass Mhalo = 1011.9±0.5 M☉. In addition, we report the [O II] detection with X-Shooter of another DLA at zabs = 0.7402 with logN(H I) = 20.4 ± 0.1 towards Q0052+0041 and an estimated SFR of 5.3 ± 0.7 M☉ yr-1. Three other objects are detected in the continuum with X-Shooter but the nature and redshift of two of these objects are unconstrained due to the absence of emission lines, while the third object might be at the redshift of the quasar. We use the objects detected in our whole N(H I)-selected SINFONI survey to compute the metallicity difference between the galaxy and the absorbing gas, δHI(X), where a positive (negative) value indicates infall (outflow). We compare this quantity with the quasar line-of-sight alignment with the galaxy's major (minor) axis, another tracer of infall (outflow).We find that these quantities do not correlate as expected from simple assumptions. Additional observations are necessary to relate these two independent probes of gas flows around galaxies. [ABSTRACT FROM AUTHOR]