Expected constraints on models of the epoch of reionization with the
  variance and skewness in redshifted 21cm-line fluctuations
  Redshifted 21cm-line signal from neutral hydrogens in the intergalactic
medium (IGM) gives a direct probe of the epoch of reionization (EoR). In this
paper, we investigate the potential of the variance and skewness of the
probability distribution function of the 21cm brightness temperature for
constraining EoR models. These statistical quantities are simple, easy to
calculate from the observed visibility and thus suitable for the early
exploration of the EoR with ongoing telescopes such as the Murchison Widefield
Array (MWA) and LOw Frequency ARray (LOFAR). We show, by performing Fisher
analysis, that the variance and skewness at $z=7-9$ are complementary to each
other to constrain the EoR model parameters such as the minimum virial
temperature of halos which host luminous objects, ionizing efficiency and mean
free path of ionizing photons in the IGM. Quantitatively, the constraining
power highly depends on the quality of the foreground subtraction and
calibration. We give a best case estimate of the constraints on the parameters,
neglecting the systematics other than the thermal noise.
