A Deep Search for Faint Galaxies Associated with Very Low Redshift C IV Absorbers. III. The Mass- and Environment-dependent Circumgalactic Medium
Abstract
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\lt z\lt 0.015, which defines a complete galaxy survey to L≳ 0.01 L\ast or stellar mass {M}* ≳ {10}8 {M}⊙ . We report two principal findings. First, for galaxies with impact parameter ρ \lt 1 {r}{vir}, C IV detection strongly depends on the luminosity/stellar mass of the nearby galaxy. C IV is preferentially associated with galaxies with {M}* \gt {10}9.5 {M}⊙ ; lower-mass galaxies rarely exhibit significant C IV absorption (covering fraction {f}C={9}-6+12 % for 11 galaxies with {M}* \lt {10}9.5 {M}⊙ ). Second, C IV detection within the {M}* \gt {10}9.5 {M}⊙ population depends on environment. Using a fixed-aperture environmental density metric for galaxies with ρ < 160 kpc at z\lt 0.055, we find that {57}-13+12 % (8/14) of galaxies in low-density regions (regions with fewer than seven L\gt 0.15 L\ast 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 {M}{halo}\gt {10}12.5 {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}})≳ 13.5 {{cm}}-2 trace the halos of {M}* \gt {10}9.5 {M}⊙ galaxies but also reflect larger-scale environmental conditions.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2016
- DOI:
- 10.3847/0004-637X/832/2/124
- arXiv:
- arXiv:1512.00853
- Bibcode:
- 2016ApJ...832..124B
- Keywords:
-
- galaxies: dwarf;
- galaxies: evolution;
- galaxies: groups: general;
- galaxies: halos;
- intergalactic medium;
- quasars: absorption lines;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 26 pages, 13 figures. ApJ, in press