Starburst Galaxies: Outflows of Metals and Energy into the IGM
  What is the contribution of mass, metals and energy from starburst galaxies
to the Intergalactic Medium? Starburst galaxies drive galactic-scale outflows
or "superwinds" that may be responsible for removing metals from galaxies and
polluting the Intergalactic Medium (IGM). In the last decade tremendous
progress was made in mapping cool entrained gas in superwinds through
UV/optical imaging and absorption line spectroscopy. These studies demonstrated
that superwinds are ubiquitous in galaxies forming stars at high surface
densities and that the most powerful starbursts can drive outflows near escape
velocity. Theoretical models of galaxy evolution have begun to incorporate
superwinds, using various ad-hoc prescriptions based on our knowledge of the
cool gas. However, these efforts are fundamentally impeded by our lack of
information about the hot phase of these outflows. The hot X-ray emitting phase
of a superwind contains the majority of its energy and newly-synthesized
metals, and given its high specific energy and inefficient cooling it is also
the component most likely escape from the galaxy's gravitational potential
well. Knowledge of the chemical composition and velocity of the hot gas are
crucial to assess the energy and chemical feedback from a starburst. A high
priority for the next decade is to enable direct measurements to be made of the
rates at which starburst galaxies of all masses eject gas, metals, and energy
into the IGM. This will require a high sensitivity X-ray imaging spectrometer
capable of measuring velocities in faint diffuse X-ray emission with a velocity
accuracy of ~ 100 km/s. Such spectral resolution automatically allows detailed
line-based plasma diagnostics, and thus composition, energetics and flow rates
can be derived.
