The Simulated Circumgalactic Medium at z∼2 Molly S. Peeples (CGE Fellow; UCLA)

1. The Simulated Circumgalactic Medium at z∼2 Molly S. Peeples (CGE Fellow; UCLA) with Ben Oppenheimer, RomeelDavé, Amanda Ford, Sean Fillingham, JunaKollmeier The Dynamic Nature of Baryons; Leiden, August 2012 How do different models of star-formation driven winds affect the circumgalactic medium at z∼2? ❶ Bulk galaxy properties ❷ The physical circumgalactic medium ❸ The observable circumgalactic medium • The Simulations • 32 h-1Mpccomoving cosmological 5123 particle SPH simulations evolved with Gadget-2 • Updated versions from Oppenheimer et al. (2010) • Wiersma et al. (2009) cooling; Haardt & Madau UV background • Compare effects of three star-formation driven wind scalings • Everything shown here is atz=2.2 • ❶ Bulk galaxy properties • Steeper wind scaling ➜ shallower low-end mass function (left), steeper mass-metallicity relation (right); very little effect on star formation rates at fixed stellar mass (middle) • Simulated star formation rates (middle) still well below those inferred from observations; see Davé (2008), Narayanan & Davé (2012) for more thorough discussions • Feedback efficiency affects metal content of the ISM (right); is the metal content of the CGM another observable consequence? z=2.2 mass-metallicity relation z=2.2 star formation rate – stellar mass relation z=2.2 halo mass – stellar mass relation ❷ The z=2.2 circumgalactic medium: physical properties • Density and temperature conspire to have higher ionization species peak at higher radii (below); this qualitative behavior is seen for all feedback models and mass ranges • details will depend on UV background • Feedback processes affect densities, temperatures, and metallicities. Left: mean stacks of 50 matched galaxies with Mhalo = 1011M☀ • 3-d profiles show detailed differences (middle); fast winds ➜higher temperatures; metallicity profiles show strong slope differences • ❸ The observable z=2.2 circumgalactic medium • Most absorption is saturated even out to large impact parameters (e.g., left, for OVI absorption around a M★~1010 galaxy in the fiducial simulation). • Stacking over multiple sightlines (below) leads to ① broader profiles than typically seen in individual spectra and ② not-as-black spectra. These effects will both be compounded with observation noise + resolution added. • Comparing at fixed stellar mass (right) allows for fairer comparison to observations: model galaxies will have made roughly the same amount of metals, so testing density of halos they live in, and where they have distributed their metals. Constant Transmitted OVI flux Fiducial Mixed • Do column density profiles measured from spectra (left) agree with the intrinsic column density profiles (right)? 1 Mpc/hcomoving ~ 446 kpc physical 300 km/s deep projections log M★=10 Stay tuned to an arXiv near you for upcoming papers…