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We propose that cooling outflows from star-forming dwarf galaxies that arespatially correlated with but unbound to bright galaxies may account for thelow column QSO Ly$\alpha$ forests, providing an explanation for both the heavyelements recently detected in them and the large sizes associated with them.Thus, we suggest that structure formations in the early universe on scaleswhere matters collapse gravitationally and the gas forms stars are responsiblefor the Ly$\alpha$ forests (cf. the mini-halo model). Supernovae shock theinterstellar gas to high temperature, and the resulting gas outflows from thedwarfs owing to their shallow potential wells. The gas cools radiatively as theradiative cooling time shortens because of adiabatic expansion. Subsequentthermal instability results in condensation of clouds. The clouds inherit thekinetic energy of the flow and coast to large distances, providing regions ofthe absorbing gas with sizes of up to hundreds of kpc. We calculate theLy$\alpha$ absorption line profiles and the neutral column distribution, andshow that they are consistent with observations. We suggest that the Ly$\alpha$forests are caused by the faint blue galaxies found in the deep extragalacticsurveys.Comment: to appear ApJ (Letters), 10 pages in uuencoded, compressed  postscript, inclduing figures

Ly-alpha forests and cooling outflow from dwarf galaxies