The influence of the Galactic wind upon the star formation histories of Local Group galaxies

We examine the possibility that ram pressure exerted by the galactic windfrom the Galaxy could have stripped gas from the Local Group dwarf galaxies,thereby affecting their star formation histories. Whether gas stripping occursor not depends on the relative magnitudes of two counteracting forces acting ongas in a dwarf galaxy: ram pressure force by the wind and the gravitationalbinding force by the dwarf galaxy itself. We suggest that the galactic windcould have stripped gas in a dwarf galaxy located within the distance of$R_{c}\simeq 120(r_{s}/1 {kpc})^{3/2} ({\cal E}_{b}/10^{50} {erg})^{-1/2}$ kpc(where $r_{s}$ is the surface radius and ${\cal E}_{b}$ is the total bindingenergy of the dwarf galaxy, respectively) from the Galaxy within a timescale ofGyr, thereby preventing star formation there. Our result based on this Galacticwind model explains the recent observation that dwarfs located close to theGalaxy experienced star formation only in the early phase of their lifetimes,whereas distant dwarfs are still undergoing star formation. The present starformation in the Large Magellanic Cloud can also be explained through ourGalactic wind model.Comment: 7 pages LaTeX, no figures, to appear in MNRA