The Properties of Two Low-Redshift O Vi Absorbers and Their Associated Galaxies Toward 3c 263,

Savage, Blair D.; Kim, T.-S.; Keeney, Brian A.; Narayanan, A.; Stocke, John T.; Syphers, David; Wakker, Bart P.

doi:10.1088/0004-637x/753/1/80

Cited by 13 publications

(19 citation statements)

References 35 publications

(50 reference statements)

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“…Several studies have already utilized this redshift survey to characterize the CGM of star-forming and passive galaxies Keeney et al 2017), to determine the maximum extent that metals spread away from their potential galaxy of origin (Stocke et al 2006;Pratt et al 2018), to probe the warm-hot intergalactic medium (WHIM) in nearby groups of galaxies (Stocke et al 2014, and to place an upper limit on the metallicity of gas clouds in cosmic voids (Stocke et al 2007). This survey also provided galaxy environments for individual absorbers of interest including two cases of demonstrably warm-hot, O VI-only absorbers (i.e., no detectable H I Lyα) in the PKS 0405-123 and FBQS 1010+3003 sight lines (Savage et al 2010;Stocke et al 2017) and a strong, multi-phase absorber in the 3C 263 sight line (Savage et al 2012).…”

Section: Discussionmentioning

confidence: 99%

A Galaxy Redshift Survey Near HST/COS AGN Sight Lines

Keeney

Stocke

Pratt

et al. 2018

ApJS

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To establish the connection between galaxies and UV-detected absorption systems in the local universe, a deep (g ≤ 20) and wide (∼ 20 radius) galaxy redshift survey is presented around 47 sight lines to UV-bright AGN observed by the Cosmic Origins Spectrograph (COS). Specific COS science team papers have used this survey to connect absorbers to galaxies, groups of galaxies, and large-scale structures, including voids. Here we present the technical details of the survey and the basic measurements required for its use, including redshifts for individual galaxies and uncertainties determined collectively by spectral class (emission-line, absorption-line, and composite spectra) and completeness for each sight line as a function of impact parameter and magnitude. For most of these sight lines the design criteria of > 90% completeness over a > 1 Mpc region down to 0.1 L * luminosities at z ≤ 0.1 allows a plausible association between low-z absorbers and individual galaxies. Lyα covering fractions are computed to approximate the star-forming and passive galaxy populations using the spectral classes above. In agreement with previous results, the covering fraction of star-forming galaxies with L ≥ 0.3 L * is consistent with unity inside one virial radius and declines slowly to > 50% at 4 virial radii. On the other hand, passive galaxies have lower covering fractions (∼ 60%) and a shallower decline with impact parameter, suggesting that their gaseous halos are patchy but have a larger scale-length than star-forming galaxies. All spectra obtained by this project are made available electronically for individual measurement and use.

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Section: Discussionmentioning

confidence: 99%

A Galaxy Redshift Survey Near HST/COS AGN Sight Lines

Keeney

Stocke

Pratt

et al. 2018

ApJS

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“…An extra H component is required to fit the weak absorption seen at ∼ −180 km s −1 . However, we adopted the total log N (H ) = 15.40 ± 0.12 as measured by the Savage et al (2012) from the unsaturated Lyγ profile using FUSE data. We thus assign a quality factor of Q = 4 for this system.…”

Section: Appendix C: Velocity Plots and System Descriptionsmentioning

confidence: 99%

COS-Weak: probing the CGM using analogues of weak Mg ii absorbers at z < 0.3

Muzahid

Fonseca

Roberts

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present a sample of 34 weak metal line absorbers at z < 0.3 selected by the simultaneous > 3σ detections of the Si λ1260 and C λ1334 absorption lines, with W r (Si ) < 0.2 Å and W r (C ) < 0.3 Å, in archival HST /COS spectra. Our sample increases the number of known low-z "weak absorbers" by a factor of > 5. The column densities of H and low-ionization metal lines obtained from Voigt profile fitting are used to build simple photoionization models. The inferred densities and line of sight thicknesses of the absorbers are in the ranges of −3.3 < log n H /cm −3 < −2.4 and ∼1 pc -50 kpc (median ≈ 500 pc), respectively. Most importantly, 85% (50%) of these absorbers show a metallicity of [Si/H] > −1.0 (0.0). The fraction of systems showing near-/super-solar metallicity in our sample is significantly higher than in the H -selected sample (Wotta et al. 2016) and the galaxy-selected sample (Prochaska et al. 2017) of absorbers probing the circum-galactic medium at similar redshift. A search for galaxies has revealed a significant galaxy-overdensity around these weak absorbers compared to random positions with a median impact parameter of 166 kpc from the nearest galaxy. Moreover, we find the presence of multiple galaxies in ≈ 80% of the cases, suggesting group environments. The observed dN/dz of 0.8 ± 0.2 indicates that such metal-enriched, compact, dense structures are ubiquitous in the halos of low-z group galaxies. We suggest that these are transient structures that are related to galactic outflows and/or stripping of metal-rich gas from galaxies.

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“…The science program of the Cosmic Origins Spectrograph (COS) Guaranteed Time Observers (GTOs; Stocke et al 2013;Keeney et al 2017) and the various HST guest observer (GO) Projects, including COS-Halos, COS-Dwarfs and COS-GASS (Tumlinson et al 2011;Werk et al 2013;Bordoloi et al 2014;Borthakur et al 2013), and the Andromeda Galaxy AMIGA project (Lehner, Howk, & Wakker 2015), among others, have gone a long way towards defining the relationship between individual galaxies, their massive photo-ionized CGMs (> 10 10 M at T ∼ 10 4 K for L ≥ L * , late-type galaxies) and the shocked interfaces with hotter gas seen as O VI absorptions (Savage et al 2010(Savage et al , 2012Tumlinson et al 2011Tumlinson et al , 2013Prochaska et al 2011;Thom et al 2012;Borthakur et al 2013;Stocke et al 2013Stocke et al , 2014Werk et al 2013Werk et al , 2014Bordoloi et al 2014;Lehner et al 2014). However dramatic the CGM detections have been, these studies still leave 50% of spiral baryons unaccounted for in the current epoch (but see Prochaska et al 2017 for an accounting in which the CGM baryon content is dominated by warm gas).…”

Section: Introductionmentioning

confidence: 99%

The Ultraviolet Detection of Diffuse Gas in Galaxy Groups

Stocke

Keeney

Danforth

et al. 2019

ApJS

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A small survey of the UV-absorbing gas in 12 low-z galaxy groups has been conducted using the Cosmic Origins Spectrograph (COS) on-board the Hubble Space Telescope (HST). Targets were selected from a large, homogeneously-selected sample of groups found in the Sloan Digital Sky Survey (SDSS). A critical selection criterion excluded sight lines that pass close (< 1.5 virial radii) to a group galaxy, to ensure absorber association with the group as a whole. to characterize these 10 13.5 to 10 14.5 M groups, the most massive of which are highly-virialized with numerous early-type galaxies (ETGs). This sample also includes two spiral-rich groups, not yet fully-virialized. At group-centric impact parameters of 0.3-2 Mpc, these S/N = 15-30 spectra detected H I absorption in 7 of 12 groups; high (O VI) and low (Si III) ion metal lines are present in 2/3 of the absorption components. None of the three most highly-virialized, ETG-dominated groups are detected in absorption. Covering fractions 50% are seen at all impact parameters probed, but do not require large filling factors despite an enormous extent. Unlike halo clouds in individual galaxies, group absorbers have radial velocities which are too low to escape the group potential well without doubt. This suggests that these groups are "closed boxes" for galactic evolution in the current epoch. Evidence is presented that the cool and warm group absorbers are not a pervasive intra-group medium (IGrM), requiring a hotter (T ∼ 10 6 to 10 7 K) IGrM to be present to close the baryon accounting.

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The Properties of Two Low-Redshift O Vi Absorbers and Their Associated Galaxies Toward 3c 263,

Cited by 13 publications

References 35 publications

A Galaxy Redshift Survey Near HST/COS AGN Sight Lines

A Galaxy Redshift Survey Near HST/COS AGN Sight Lines

COS-Weak: probing the CGM using analogues of weak Mg ii absorbers at z < 0.3

The Ultraviolet Detection of Diffuse Gas in Galaxy Groups

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