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 rangesdetails will depend on UV

background

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

with Ben Oppenheimer, Romeel Davé,Amanda Ford, Sean Fillingham, Juna Kollmeier

The Dynamic Nature of Baryons; Leiden, August 2012

Stay tuned to an arXiv near you for upcoming papers…

Wind Model Wind velocity vw Mass-loading factor ηw

Fiducial:momentum-driven scaling vw = [150 km/s] / σgal ηw σ∝ gal

-1

Mixed: v-2 energy-driven scaling for dwarfs vw = [150 km/s] / σgal

σgal > 75 km/s: ηw σ∝ gal-1

σgal < 75 km/s: ηw σ∝ gal-2

constant wind vw = 680 km/s ηw = 2

€

ηwind ≡˙ M wind˙ M SFR

The Simulations 32 h-1 Mpc comoving 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 at z=2.2

z=2.2 star formation rate – stellar mass relation

z=2.2 mass-metallicity relation

❷ The z=2.2 circumgalactic medium: physical properties

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?

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

❸ The observable z=2.2 circumgalactic mediumMost 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.

log M★=10 1 Mpc/h comoving ~ 446 kpc physical300 km/s deep projections

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VI fl

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z=2.2 halo mass – stellar mass relation

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

Fidu

cial

Cons

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Do column density profiles measured from spectra (left) agree with

the intrinsic column density profiles (right)?