4. OUTFLOWS FROM GALAXIES WITH BOTH STARBURST AND AGN ACTIVITY

The soft X-ray properties of many actively star-forming galaxies with spatially-extended soft X-ray emission are in accord with models of supernova-driven winds. But what of starburst galaxies that also host AGN? In general the outflows from classic starburst galaxies that also host LLAGN (NGC 253, NGC 3079) do not differ from winds from pure starbursts (M82, NGC 3628, see Strickland et al. 2004a). The one "classic" starburst that does appear unusual is NGC 4945, which is also the host of a very peculiar X-ray-luminous AGN that is probably heavily obscured along all lines of sight (Levenson et al., 2002; Marconi et al., 2000). Although it has a X-ray and H nuclear outflow cone similar to NGC 253, it is lacking in diffuse X-ray or H emission when compared to a starburst of the same total galactic bolometric luminosity, log L_{X, TOT} / L_BOL = - 4.25 (Strickland et al., 2004a). However, the AGN may dominate L_BOL. If we assume that the diffuse X-ray emission is due to a starburst-driven wind alone, then the starburst must only account for 20% of L_BOL. In general, the large-scale soft X-ray emission in Seyfert/Starburst composite galaxies is consistent with a purely-starburst origin (Levenson et al., 2001b; Levenson et al., 2004; Levenson et al., 2001a). Thus, for a given total bolometric luminosity it appears that SNe are more effective at driving galactic-scale winds than AGN.. This does not imply that AGN-driven galactic winds do not exist. There clearly are galaxies with AGN but lacking starbursts that have galactic-scale (i.e. ~ 10 kpc) outflows (Colbert et al., 1996; Colbert et al., 1998), but their local space density is lower than typical starburst superwind galaxies.