Effects of the sources of reionization on 21-cm redshift-space
  distortions
  The observed 21-cm signal from the epoch of reionization will be distorted
along the line-of-sight by the peculiar velocities of matter particles. These
redshift-space distortions will affect the contrast in the signal and will also
make it anisotropic. This anisotropy contains information about the
cross-correlation between the matter density field and the neutral hydrogen
field, and could thus potentially be used to extract information about the
sources of reionization. In this paper, we study a collection of simulated
reionization scenarios assuming different models for the sources of
reionization. We show that the 21-cm anisotropy is best measured by the
quadrupole moment of the power spectrum. We find that, unless the properties of
the reionization sources are extreme in some way, the quadrupole moment evolves
very predictably as a function of global neutral fraction. This predictability
implies that redshift-space distortions are not a very sensitive tool for
distinguishing between reionization sources. However, the quadrupole moment can
be used as a model-independent probe for constraining the reionization history.
We show that such measurements can be done to some extent by first-generation
instruments such as LOFAR, while the SKA should be able to measure the
reionization history using the quadrupole moment of the power spectrum to great
accuracy.
