J/MNRAS/449/3263   Extended galaxy halo gas through HI and OVI  (Johnson+, 2015)
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On the possible environmental effect in distributing heavy elements beyond
individual gaseous haloes.
    Johnson S.D., Chen H.-W., Mulchaey J.S.
   <Mon. Not. R. Astron. Soc., 449, 3263-3273 (2015)>
   =2015MNRAS.449.3263J    (SIMBAD/NED BibCode)
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ADC_Keywords: QSOs ; Galaxies, spectra
Keywords: galaxies: haloes - galaxies: interactions - intergalactic medium -
          quasars: absorption lines

Abstract:
    We present a study of extended galaxy halo gas through HI and OVI
    absorption over two decades in projected distance at z~0.2. The study
    is based on a sample of 95 galaxies from a highly complete (>80
    percent) survey of faint galaxies (L>0.1L*) with archival quasar
    absorption spectra and 53 galaxies from the literature. A clear
    anticorrelation is found between HI (OVI) column density and virial
    radius normalized projected distance, d/Rh. Strong HI (OVI) absorption
    systems with column densities greater than 10^14.0^ (10^13.5^)cm^-2^
    are found for 48 of 54 (36 of 42) galaxies at d<Rh indicating a mean
    covering fraction of <{kappa}_HI_>=0.89 (<{kappa}_OVI_>=0.86). OVI
    absorbers are found at d~Rh, beyond the extent observed for lower
    ionization species. At d/Rh=1-3 strong HI (OVI) absorption systems are
    found for only 7 of 43 (5 of 34) galaxies (<{kappa}_HI_>=0.16 and
    <{kappa}_OVI_>=0.15). Beyond d=3Rh, the HI and OVI covering fractions
    decrease to levels consistent with coincidental systems. The high
    completeness of the galaxy survey enables an investigation of
    environmental dependence of extended gas properties. Galaxies with
    nearby neighbours exhibit a modest increase in Ovi covering fraction
    at d>Rh compared to isolated galaxies (<{kappa}_OVI_~0.13 versus 0.04)
    but no excess HI absorption. These findings suggest that environmental
    effects play a role in distributing heavy elements beyond the enriched
    gaseous haloes of individual galaxies. Finally, we find that
    differential HI and OVI absorption between early- and late-type
    galaxies continues from d<Rh to d~3Rh.

Description:
    To assemble the eCGM galaxy sample, we combined our own
    absorption-blind survey data targeting galaxies of rAB<23mag in the
    fields of HE 0226-4110, PKS 0405-123, LBQS 1435-0134, and
    PG 1522+101 with spectroscopic galaxies in the SDSS Data Release 10
    (DR10; York et al., 2000AJ....120.1579Y; Ahn et al.,
    2014ApJS..211...17A).

    The HE 0226-4110, PKS 0405-123, LBQS 1435-0134, and PG 1522+101
    fields were selected because of the high completeness levels
    (80 per cent) achieved by our surveys for galaxies as faint as
    L=0.1L* at z<0.4 and d<500kpc. At smaller projected distances of d=100
    and 200kpc, the survey completeness increases to 100 and
    90 per cent, respectively (see fig. 2 of Johnson, Chen & Mulchaey,
    2013, Cat. J/MNRAS/434/1765). We included SDSS galaxies to increase
    the number of eCGM sample members of logM*/M_{sun}_>11. The resulting
    galaxy sample is summarized in Table 1.

File Summary:
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 FileName      Lrecl  Records   Explanations
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ReadMe            80        .   This file
table1.dat       108      148   Summary of galaxy and absorber properties
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See also:
    J/MNRAS/434/1765 : Catalog of galaxies around PKS 0405-123 (Johnson+, 2013)
    http://www.sdss3.org : SDSS-III website

Byte-by-byte Description of file: table1.dat
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   Bytes Format Units    Label     Explanations
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   1- 14  A14   ---      Name      Galaxy sightline name
  16- 17  I2    h        RAh       Right ascension (J2000)
  19- 20  I2    min      RAm       Right ascension (J2000)
  22- 26  F5.2  s        RAs       Right ascension (J2000)
      28  A1    ---      DE-       Declination sign (J2000)
  29- 30  I2    deg      DEd       Declination (J2000)
  32- 33  I2    arcmin   DEm       Declination (J2000)
  35- 38  F4.1  arcsec   DEs       Declination (J2000)
  40- 45  F6.4  ---      zgal      Galaxy redshift
  47- 50  F4.1  [Msun]   logM*     Stellar mass
  52- 56  A5    ---      Class     [Early Late] Classification (1)
  58- 59  A2    ---      Env       [I NI A] Environment class (2)
  61- 69  A9    ---      Survey    Survey
  71- 73  I3    kpc      d         Distance
  75- 78  F4.1  ---      d/Rh      Virial radius normalized projected distance
      80  A1    ---    l_logNHI    Limit flag on logNHI
  81- 85  F5.2  [cm-2]   logNHI    ?=-1 HI column density
  87- 90  F4.2  [cm-2] e_logNHI    ? rms uncertainty on logNHI
      91  A1    ---      ---       [-]
  92- 96  F5.2  [cm-2]   logNHIu   ? Upper value of logNHI when interval
      98  A1    ---    l_logNHOVI  Limit flag on logNHOVI
  99-103  F5.2  [cm-2]   logNHOVI  ?=-1 OIV column density (3)
 105-108  F4.2  [cm-2] e_logNHOVI  ? rms uncertainty on logNHOVI
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Note (1): Galaxy classification as follows:
    Early = early-type, absorption-line dominated galaxies
    Late  = late-type, emission-line dominated galaxies
Note (2): Galaxy environment class defined  as follows:
    I = isolated
   NI = non-isolated
    A = ambiguous cases
Note (3): Total column density measured in the COS sightline within
   {Delta}V=+/-300km/s of the galaxy systemic redshift.
   In cases where OVI or HI column densities cannot be measured due to
   contamination, the value is set to -1.
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History:
    From electronic version of the journal

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(End)                                      Patricia Vannier [CDS]    10-Dec-2015