Far-Ultraviolet Observations of Outflows from IR-Luminous Galaxies
  We obtained medium-resolution ultraviolet (UV) spectra between 1150 and 1450
Angstroms of the four UV-bright, infrared (IR)-luminous starburst galaxies IRAS
F08339+6517, NGC 3256, NGC 6090, and NGC 7552 using the Cosmic Origins
Spectrograph onboard the Hubble Space Telescope. The selected sightlines
towards the starburst nuclei probe the properties of the recently formed
massive stars and the physical conditions in the starburst-driven galactic
superwinds. Despite being metal-rich and dusty, all four galaxies are strong
Lyman-alpha emitters with equivalent widths ranging between 2 and 13 Angstroms.
The UV spectra show strong P Cygni-type high-ionization features indicative of
stellar winds and blueshifted low-ionization lines formed in the interstellar
and circumgalactic medium. We detect outflowing gas with bulk velocities of
about 400 km/s and maximum velocities of almost 900 km/s. These are among the
highest values found in the local universe and comparable to outflow velocities
found in luminous Lyman-break galaxies at intermediate and high redshift. The
outflow velocities are unlikely to be high enough to cause escape of material
from the galactic gravitational potential. However, the winds are significant
for the evolution of the galaxies by transporting heavy elements from the
starburst nuclei and enriching the galaxy halos. The derived mass outflow rates
of ~100 Msol/yr are comparable to, or even higher than the star-formation
rates. The outflows can quench star formation and ultimately regulate the
starburst as has been suggested for high-redshift galaxies.
