Are Ly{\alpha} emitters segregated in protoclusters regions?
  The presence of neutral hydrogen in the inter-stellar medium (ISM) and
inter-galactic medium (IGM) induces radiative transfer (RT) effects on
Ly{\alpha} photons which affect the observability of Ly{\alpha} emitters
(LAEs). We use the GALFORM semi-analytic model of galaxy formation and
evolution to analyse how these effects shape the spatial distribution of LAEs
with respect to H{\alpha} emitters (HAEs) around high density regions at high
redshift. We find that when a large sample of protoclusters is considered, HAEs
showing also Ly{\alpha} emission (HAEs+LAEs) populate the same regions as those
that do not display the Ly{\alpha} line at $z=2.2$. We compare against the
protocluster USS1558-003, one of the most massive protoclusters located at
$z=2.53$. Our results indicate that the strong depletion of HAEs+LAEs present
in the high density regions of USS1558-003 may be due to cosmic variance. We
find that at $z=2.2$ and $z=3.0$, RT of the ISM produces a strong decline
($30$-$50$ per cent) of the clustering amplitude of HAEs+LAEs with respect to
HAEs towards the protoclusters centre. At $z=5.7$, given the early evolutionary
state of protoclusters and galaxies, the clustering of HAEs+LAEs has a smaller
variation ($10$-$20$ per cent) towards the protoclusters centre. Depending on
the equivalent width and luminosity criteria of the emission-line galaxy
sample, the IGM can have a mild or a null effect on galaxy properties and
clustering in high density regions.
