Metal Enrichment of Ly alpha Clouds and Intergalactic Medium

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We have examined the metal enrichment of the intergalactic medium (IGM) based on a galactic wind model. A galactic wind driven by supernovae brings metallic gas to the IGM but not so far beyond the gravitational potential. The expanding velocity of the outflow depends on the star formation timescale. Examining 3D calculation for the IGM in CDM model, we find that only 10 % region has metallicity larger than 10⁻²Z at z=3. Wide range of the IGM metallicity produces variety of CIV column densities for a fixed HI column density.