The Lyman Continuum Escape and ISM properties in Tololo 1247-232 - New
  Insights from HST and VLA
  Low- and intermediate mass galaxies are widely discussed as cause of
reionization at redshift $z\sim10-6$. However, observational proof of galaxies
that are leaking ionizing radiation (Lyman continuum; LyC) is a currently
ongoing challenge and the list of LyC emitting candidates is still short.
Tololo 1247-232 is among those very few galaxies with recently reported
leakage. We performed intermediate resolution ultraviolet (UV) spectroscopy
with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope
and confirm ionizing radiation emerging from Tololo 1247-232. Adopting an
improved data reduction procedure, we find that LyC escapes from the central
stellar clusters, with an escape fraction of 1.5$\pm$0.5% only, i.e. the lowest
value reported for the galaxy so far. We further make use of FUV absorption
lines of Si II and Si IV as a probe of the neutral and ionized interstellar
medium. We find that most of the ISM gas is ionized, likely facilitating LyC
escape from density bounded regions. Neutral gas covering as a function of
line-of-sight velocity is derived using the apparent optical depth method. The
ISM is found to be sufficiently clumpy, supporting the direct escape of LyC
photons. We further report on broadband UV and optical continuum imaging as
well as narrowband imaging of Ly$\alpha$, H$\alpha$ and H$\beta$. Using stellar
population synthesis, a Ly$\alpha$ escape fraction of 8% was derived. We also
performed VLA 21cm imaging. The hydrogen hyperfine transition was not detected,
but a deep upper limit atomic gas mass of $\lesssim10^9 M_{\odot}$ could be
derived. The upper limit gas fraction defined as $\frac{M_{H I}}{M_*}$ is only
20%. Evidence is found that the H I gas halo is relatively small compared to
other Lyman Alpha emitters.
