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We analyze the low-redshift (z~0.2) circumgalactic medium by comparingabsorption-line data from the COS-Halos Survey to absorption around a matchedgalaxy sample from two cosmological hydrodynamic simulations. The modelsinclude different prescriptions for galactic outflows, namely hybridenergy/momentum driven wind (ezw), and constant winds (cw). We extract forcomparison direct observables including equivalent widths, covering factors,ion ratios, and kinematics. Both wind models are generally in good agreementwith these observations for HI and certain low ionization metal lines, but showpoorer agreement with higher ionization metal lines including SiIII and OVIthat are well-observed by COS-Halos. These discrepancies suggest that both windmodels predict too much cool, metal-enriched gas and not enough hot gas, and/orthat the metals are not sufficiently well-mixed. This may reflect our modelassumption of ejecting outflows as cool and unmixing gas. Our ezw simulationincludes a heuristic prescription to quench massive galaxies by super-heatingits ISM gas, which we show yields sufficient low ionisation absorption to bebroadly consistent with observations, but also substantial OVI absorption thatis inconsistent with data, suggesting that gas around quenched galaxies in thereal Universe does not cool. At impact parameters of <50 kpc, recycling windsdominate the absorption of low ions and even HI, while OVI almost always arisesfrom metals ejected longer than 1 Gyr ago. The similarity between the windmodels is surprising, since we show that they differ substantially in theirpredicted amount and phase distribution of halo gas. We show that thissimilarity owes mainly to our comparison here at fixed stellar mass rather thanat fixed halo mass in our previous works, which suggests that CGM propertiesare more closely tied to the stellar mass of galaxies rather than halo mass.

Baryon Cycling in the Low-Redshift Circumgalactic Medium: A Comparison of Simulations to the COS-Halos Survey