SDSS-IV MaNGA: an observational evidence of density bounded region in a
  Lyman-$\alpha$ emitter
  Using Integral Field Unit (IFU) spectroscopy, we present here the spatially
resolved morphologies of [SII]$\lambda$6717,6731/H$\alpha$ and
[SII]$\lambda$6717,6731/[OIII]$\lambda$5007 emission line ratios for the first
time in a Blueberry Lyman-$\alpha$ emitter (BBLAE) at z $\sim$ 0.047. Our
derived morphologies show that the extreme starburst region of the BBLAE,
populated by young ($\leqslant$ 10 Myr), massive Wolf-Rayet stars, is
[SII]-deficient, while the rest of the galaxy is [SII]-enhanced. We infer that
the extreme starburst region is density-bounded (i.e., optically thin to
ionizing photons), and the rest of the galaxy is ionization-bounded $-$
indicating a Blister-type morphology. We find that the previously reported
small escape fraction (10%) of Ly$\alpha$ photons is from our identified
density-bounded HII region of the BBLAE. This escape fraction is likely
constrained by a porous dust distribution.
  We further report a moderate correlation between [SII]-deficiency and
inferred Lyman Continuum (LyC) escape fraction using a sample of confirmed LyC
leakers studied in the literature, including the BBLAE studied here. The
observed correlation also reveals its dependency on the stellar mass and
gas-phase metallicity of the leaky galaxies. Finally, the future scope and
implications of our work are discussed in detail.
