Baryon Acoustic Oscillations reconstruction with pixels
  Gravitational non-linear evolution induces a shift in the position of the
baryon acoustic oscillations (BAO) peak together with a damping and broadening
of its shape that bias and degrades the accuracy with which the position of the
peak can be determined. BAO reconstruction is a technique developed to undo
part of the effect of non-linearities. We present and analyse a reconstruction
method that consists of displacing pixels instead of galaxies and whose
implementation is easier than the standard reconstruction method. We show that
this method is equivalent to the standard reconstruction technique in the limit
where the number of pixels becomes very large. This method is particularly
useful in surveys where individual galaxies are not resolved, as in 21cm
intensity mapping observations. We validate this method by reconstructing mock
pixelated maps, that we build from the distribution of matter and halos in
real- and redshift-space, from a large set of numerical simulations. We find
that this method is able to decrease the uncertainty in the BAO peak position
by 30-50% over the typical angular resolution scales of 21 cm intensity mapping
experiments.
