Lyman continuum leaking galaxies - Search strategies and local
  candidates
  Star-forming dwarf galaxies leaking Lyman-continuum (LyC) radiation may have
played an important role in the reionization of the Universe. Local galaxies
exhibiting LyC leakage could shed light on the escape mechanisms, but so far
only two such cases have been identified. Here we want to investigate whether
the lack of local LyC emitters can be caused in part by biased selection
criteria (e.g. strong H-alpha emission), and we present a novel method of
selecting targets with high escape fractions. By applying these criteria, we
assemble a sample of observation targets to study their basic properties.
  We introduce a new strategy where potential LyC leakers are selected by their
blue colours and weak (instead of strong) emission lines. We take a closer look
at 8 LyC leaking candidates at z ~ 0.03, selected from the Sloan Digital Sky
Survey (SDSS), which we observe with ESO/NTT in broadband B and H-alpha. We
find that 7 of the 8 galaxies are involved in interaction with neighbours or
show signs of mergers. In 7 cases the young stellar population is clearly
displaced from the main body of the galaxies. Half of our targets show
absorption spectra with post-starburst signatures. The scale lengths in H-alpha
are typically 30% smaller than those of the stellar continua, indicating ram
pressure stripping. We tentatively identify a few conditions favourable for
leakage: 1) the combined effects of ram pressure stripping with supernova winds
from young stars formed in the front, 2) merger events that increase the star
formation rate and displace stars from gas, 3) starbursts in the centres of
post-starburst galaxies, and 4) a low dust content.
