To appear in "Extragalactic Gas at Low Redshift",
ed. J. Mulchaey and J. Stocke, ASP Conf. Series;
astro-ph/0107438
For a postscript version of the article, click
here.
GALACTIC SUPERWINDS CIRCA 2001
Timothy M. Heckman
Department of Physics & Astronomy, The Johns Hopkins University,
Baltimore, MD 21218
Abstract.
In this contribution I summarize our current knowledge of the nature
and significance of starburst-driven galactic winds ("superwinds").
Superwinds are complex multiphase
outflows of cool, warm, and hot gas, dust, and magnetized
relativistic plasma.
The observational manifestations of superwinds result from the
hydrodynamical interaction between the primary energy-carrying wind fluid
and the ambient interstellar medium.
Superwinds are ubiquitous
in galaxies in which the global star-formation rate per unit area
exceeds roughly 10-1
M
yr-1 kpc-2. This
criterion is met by local starbursts and the high-z Lyman Break galaxies.
Several independent datasets and techniques imply that the total
mass and energy outflow rates
in a superwind are comparable to the starburst's
star-formation-rate and mechanical energy injection rate, respectively.
Outflow speeds in interstellar
matter entrained in the wind range from
∼ 102 to 103 km/s, but the primary
wind fluid itself may reach velocities as high as ∼ 3000 km
s-1. The available
X-ray and far-UV (FUSE) data
imply that radiative losses in superwinds are not significant.
Superwinds may have established the mass-metallicity relation
in ellipticals and bulges, polluted the present-day inter-galactic
medium to a metallicity of ∼ 10 to 30% solar, heated the
inter-galactic medium, and ejected
enough dust into the inter-galactic medium to have potentially observable
consequences.
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