AAS 198th Meeting, June 2001
Session 57. Cosmological Impact of Galactic Winds

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[57.03] Cosmological Feedback and Metal Ejection from High-Redshift Dwarf Galaxies

A. Fujita (American Museum of Natural History/Columbia University), M.-M. Mac Low (American Museum of Natural History), A. Meiksin (U. Edinburgh), A. Ferrara (Oss. Astrofisico di Arcetri)

According to the theory of hierarchical structure formation, small-scale structures such as dwarf galaxies form first, as protogalactic gas clouds of mass M\approx108-9M\odot start to collapse at high redshift. Such dwarf galaxies are building blocks of larger structures such as the disk galaxies that we see today. Therefore, understanding the formation and evolution of dwarf galaxies enables us to address some unresolved problems in galaxy formation:

1. How can a disk of a present-day disk galaxy be formed, when infalling gas in the halo first overcools in dwarf-sized halos and then loses too much angular momentum as the resulting dwarf galaxies merge with each other?

2. Where do the heavy elements, ~.1-1% of solar content, observed in Lyman \alpha forest absorbers at z \geq 3 come from?

We model the effects of repeated supernova explosions from starbursts in high-redshift dwarf galaxies, using ZEUS-3D, a second-order, Eulerian, astrophysical gas dynamics code (Stone & Norman 1992). Dwarf galaxies are embedded in an evolving cosmological background, which is computed with a one-dimensional numerical hydrodynamics code with Gaussian perturbation (Meiksin 1994). We study the rate of mass loss and energy output ('feedback') and the rate of metal ejection from such dwarf galaxies to the IGM, as a function of the mass and time of formation of the galaxy, and the size of the starburst.

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