A high spatial resolution X-ray and H-alpha study of hot gas in the halos of star-forming disk galaxies. II. Quantifying supernova feedback
Abstract
We investigate how the empirical properties of hot X-ray-emitting gas in a sample of 7 starburst and 3 normal edge-on spiral galaxies correlate with the size, mass, star formation rate and star formation intensity in the host galaxies. From this analysis we investigate various aspects of mechanical energy feedback on galactic scales. We demonstrate, using a variety of multi-wavelength star formation rate and intensity indicators, that the diffuse X-ray emission is ultimately driven by mechanical energy feedback from massive stars. We find that the luminosity of the extra-planar diffuse X-ray emission is proportional to proxies of the star formation rate of the host galaxy, for example the FIR or 1.4 GHz radio luminosity. Larger galaxies tend to have more extended X-ray-emitting halos, but galaxy mass appears to play no role in determining the properties of the disk or extra-planar X-ray emitting plasma. Accretion of gas from the IGM does not appear to be a significant contributor to the diffuse X-ray emission in this sample. The combination of these luminosity and size correlations leads to a correlation between the X-ray surface brightness and L_FIR/D_25^2. Intriguingly, the diffuse X-ray properties of the normal spirals fall where extrapolation of the trends from the starburst galaxies with superwinds would predict. We reconsider the conditions necessary for superbubble blow-out from the disk into the halo of a galaxy, and present methods for observationally determining the efficiency of mechanical energy feedback and testing theoretical models of disk blow out. Given the properties of the gaseous halos we observe, outflows from disk galaxies of mass M = 1e10 to 1e11 Solar masses should still eject some fraction of their material in the IGM.Keywords
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