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We study the physical conditions of the circum-galactic medium (CGM) aroundz=0.25 galaxies as traced by HI and metal line absorption, using cosmologicalhydrodynamic simulations that include galactic outflows. Using lines of sighttargeted at impact parameters from 10 kpc to 1 Mpc around galaxies with halomasses from 10^11-10^13 M_solar, we study the physical conditions and theirvariation with impact parameter b and line-of-sight velocity delta v in the CGMas traced by HI, MgII, SiIV, CIV, OVI, and NeVIII absorbers. All ions show astrong excess of absorption near galaxies compared to random lines of sight.The excess continues beyond 1 Mpc, reflecting the correlation of metalabsorption with large-scale structure. Absorption is particularly enhancedwithin about v<300 km/sec and roughly 300 kpc of galaxies (with distancessomewhat larger for the highest ion), approximately delineating the CGM; thisrange contains the majority of global metal absorption. Low ions like MgII andSiIV predominantly arise in denser gas closer to galaxies and drop more rapidlywith b, while high ions OVI and NeVIII trace more diffusely distributed gaswith a comparatively flat radial profile; CIV is intermediate. All ionspredominantly trace T~10^4-4.5 K photo-ionised gas at all b, but when hot CGMgas is present (mostly in larger halos), we see strong collisionally-ionisedOVI and NeVIII at b <= 100 kpc. Larger halo masses generally produce moreabsorption, though overall the trends are not as strong as that with impactparameter. These findings arise using our favoured outflow scalings as expectedfor momentum-driven winds; with no winds, the CGM gas remains mostlyunenriched, while our outflow model with a constant velocity and mass loadingfactor produce hotter, more widely dispersed metals.

Hydrogen and Metal Line Absorption Around Low-Redshift Galaxies in Cosmological Hydrodynamic Simulations