Astrophys. J., 832, 124-124 (2016/December-1)
A deep search for faint galaxies associated with very low redshift C IV absorbers. III. The mass- and environment-dependent circumgalactic medium.
BURCHETT J.N., TRIPP T.M., BORDOLOI R., WERK J.K., PROCHASKA J.X., TUMLINSON J., WILLMER C.N.A., O'MEARA J. and KATZ N.
Abstract (from CDS):
Using Hubble Space Telescope Cosmic Origins Spectrograph observations of 89 QSO sightlines through the Sloan Digital Sky Survey footprint, we study the relationships between C iv absorption systems and the properties of nearby galaxies, as well as the large-scale environment. To maintain sensitivity to very faint galaxies, we restrict our sample to 0.0015< z< 0.015, which defines a complete galaxy survey to L>rsim 0.01 L*or stellar mass M*>rsim 108 M☉. We report two principal findings. First, for galaxies with impact parameter ρ< 1 rvir, C iv detection strongly depends on the luminosity/stellar mass of the nearby galaxy. C iv is preferentially associated with galaxies with M*> 109.5 M☉; lower-mass galaxies rarely exhibit significant C iv absorption (covering fraction fC=9–6+12 % for 11 galaxies with M*< 109.5 M☉). Second, C iv detection within the M*> 109.5 M☉ population depends on environment. Using a fixed-aperture environmental density metric for galaxies with ρ < 160 kpc at z< 0.055, we find that 57–13+12 % (8/14) of galaxies in low-density regions (regions with fewer than seven L> 0.15 L*galaxies within 1.5 Mpc) have affiliated C iv absorption; however, none (0/7) of the galaxies in denser regions show C iv. Similarly, the C iv detection rate is lower for galaxies residing in groups with dark matter halo masses of Mhalo> 1012.5 M☉. In contrast to C iv, H i is pervasive in the circumgalactic medium without regard to mass or environment. These results indicate that C iv absorbers with log N(C IV)>rsim 13.5 cm–2 trace the halos of M*> 109.5 M☉ galaxies but also reflect larger-scale environmental conditions.
© 2016. The American Astronomical Society. All rights reserved.
galaxies: dwarf - galaxies: evolution - galaxies: groups: general - galaxies: halos - intergalactic medium - quasars: absorption lines - quasars: absorption lines
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