The COS-legacy survey of C IV absorbers: properties and origins of the intervening systems

We present here results from a survey of intervening C IV absorbers at $z < 0.16$ conducted using 223 sightlines from the Hubble Spectroscopic Legacy Archive. Most systems (83%) out of the total sample of 69 have simple kinematics with 1 or 2 C IV components. In the 22 C IV systems with well constrained H I column densities, the temperatures from the $b$-values imply predominantly photoionized plasma ($Tleq 10^5$ K) and non-thermal dynamics. These systems also have solar or higher metallicities. We obtain a C IV line density of $dmathcal{N}/dX = 5.1pm 1.0$ for $log [N(C~IV)~(cm^{-2})]geq12.9$, and $Omega_{C~IV}=(8.01pm 1.62) times 10^{-8}$ for $12.9 leq log [N(C~IV)~(cm^{-2})] leq 15.0$. The C IV bearing diffuse gas in the $z < 0.16$ Universe has a metallicity of $(2.07~{pm}~0.43)~times~10^{-3}$ Z$_{odot}$, an order of magnitude more than the metal abundances in the IGM at high redshifts ($z gtrsim 5$), and consistent with the slow build-up of metals in the diffuse circum/intergalactic space with cosmic time. For $z<0.015$ (complete above $L>0.01L^star$), the Sloan Digital Sky Survey provides a tentative evidence of declining covering fraction for strong C IV ($N>10^{13.5}~cm^{-2}$) with $rho$ (impact parameter) and $rho/R_mathrm{vir}$. However, the increase at high separations suggests that strong systems are not necessarily coincident with such galaxies. We also find that strong C IV absorption at $z<0.051$ is not coincident with galaxy over-dense regions complete for $L>0.13L^star$