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G. Bryan (MIT)
If galactic winds escape their host galaxies and impact the intergalactic medium (IGM) then probes of the diffuse IGM, such as the Lyman-alpha forest, should reflect this tremendous energy input. Surprisingly, simulations that do not include winds accurately reproduce the observed Lyman-alpha absorption properties. On the other hand, new metal-line observations indicate that the low-density IGM has been polluted with metals (presumably via galactic outflows). In this talk, I will summarize the conflicting observational evidence and then present results from cosmological simulations which include galactic feedback in order to try to answer the following questions: (1) how would energy injection into the IGM modify the predicted Lyman-alpha statistics? (2) what are the metal line observations really telling us? (3) can the low temperature of the IGM be reconciled with the large amount of pre-heating that gas in groups and clusters seems to have undergone?