Joint Astrophysics Colloquium

Galactic Outflows and Evolution of the Intergalactic Medium

Hugo Martel

Université Laval

We have designed an analytical model for anisotropic galactic outflows. With this model, we study the impact of anisotropic outflows in the evolution of the IGM, focussing on (1) the distribution of metals and its observational signature in spectra of QSO's, (2) the positive feedback resulting for the increased cooling rate of the IGM due to metal enrichment, and (3) the negative feedback resulting from ram-pressure stripping of proto-galaxies. Outflows travel preferentially into low-density regions, away from other galaxies. As a result, the suppression of galaxy formation by ram-pressure stripping, and the cross-pollution in metals between galaxies, are greatly reduced.

These supernovae-driven outflows are produced predominently by low-mass galaxies. These galaxies are precisely the ones that are affected by the reionization of the universe. We consider several reionization scenarios, estimate the resulting suppresion of dwarf galaxies, and the impact of this suppresion on the deposition of metals in the IGM.