The source responsible for reionizing the universe at z > 6 remains
uncertain. While an energetically adequate population of star-forming galaxies
may be in place, it is unknown whether a large enough fraction of their
ionizing radiation can escape into the intergalactic medium. Attempts to
measure this escape-fraction in intensely star-forming galaxies at lower
redshifts have largely yielded upper limits. In this paper we present new HST
COS and archival FUSE far-UV spectroscopy of a sample of eleven Lyman Break
Analogs (LBAs), a rare population of local galaxies that strongly resemble the
high-z Lyman Break galaxies. We combine these data with SDSS optical spectra
and Spitzer photometry. We also analyze archival FUSE observations of fifteen
typical UV-bright local starbursts. We find evidence of small covering factors
for optically-thick neutral gas in 3 cases. This is based on two independent
pieces of evidence: a significant residual intensity in the cores of the
strongest interstellar absorption-lines tracing neutral gas and a small ratio
of extinction-corrected H-alpha to UV plus far-IR luminosities. These objects
represent three of the four LBAs that contain a young, very compact (~100pc),
and highly massive (~10^9 Mo) dominant central object (DCO). These three
objects also differ from the other galaxies in showing a significant amount of
blueshifted Ly-alpha emission, which may be related to the low covering factor
of neutral gas. All four LBAs with DCOs in our sample show extremely high
velocity outflows of interstellar gas, with line centroids blueshifted by about
700km/s and maximum outflow velocities reaching at least 1500km/s. We show that
these properties are consistent with an outflow driven by a powerful starburst
that is exceptionally compact. We speculate that such extreme feedback may be
required to enable the escape of ionizing radiation from star forming galaxies.Comment: Accepted for publication in ApJ. 14 pages, 8 figures, 2 table
