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Session 38 - Modeling & Numerical Methods.
Display session, Wednesday, June 11
South Main Hall,

[38.07] Testing Cosmological Models Using Damped Lyman-Alpha Absorbers

J. P. Gardner (U. Washington), N. Katz (U. Mass.), D. H. Weinberg (Ohio State U.), L. Hernquist (U.C. Santa Cruz)

Damped Lyman-alpha absorption systems probe the distribution of collapsed, cold gas at high redshift. Numerical simulations that incorporate gravity and gas dynamics can, when analyzed appropriately, be used to predict the abundance of such absorbers in cosmological models. We calculate the number of damped Lyman-alpha absorbers as a function of redshift expected in various popular cosmological scenarios and compare our predictions with observed abundances. The Press-Schechter formalism is used to obtain the distribution of halos with circular velocity, and we calibrate the relation between circular velocity and absorption cross-section using detailed gas dynamical simulations. Because of this calibration, our approach makes more realistic assumptions about the absorption properties of collapsed objects than previous, analytic calculations of the damped Lyman-alpha abundance.

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