Galactic Superwinds at Low and High Redshift

In this contribution I summarize our current knowledge of the nature and significance of starburst-driven galactic superwinds. These flows are driven primarily by the kinetic energy supplied by supernovae. Superwinds are complex, multiphase phenomena requiring a panchromatic observational approach. They are ubiquitous in galaxies in which the global star-formation rate per unit area exceeds roughly 10 M⊙ yr kpc (a condition satisfied by local starbursts and high-z Lyman Break galaxies). Data on X-ray emission, optical line-emission, and optical/UV interstellar absorption-lines together imply that the mass outflow rates are comparable to the star-formation-rates and that the conversion of kinetic energy from supernovae to superwind is quite efficient (∼ 30 to 100%). Measured/inferred outflow speeds range from a few ×10 to 10 km/s and appear to be independent of the rotation speed of the “host” galaxy. The outflows are dusty (dust/gas ratios of ∼ 1% by mass). These properties imply that superwinds may have established the massmetallicity relation in elliptical and bulges, polluted the inter-galactic medium to a metallicity of ∼ 10 to 30% solar, heated the inter-galactic medium by up to ∼1 kev per baryon, and ejected enough dust into the inter-galactic medium to have potentially observable consequences.