The impact of non-Gaussianity on the Epoch of Reionization parameter
  forecast using 21-cm power spectrum measurements
  Measurements of the Epoch of Reionization (EoR) 21-cm signal hold the
potential to constrain models of reionization. In this paper we consider a
reionization model with three astrophysical parameters namely (1) the minimum
halo mass which can host ionizing sources, $M_{\rm min}$, (2) the number of
ionizing photons escaping into the IGM per baryon within the halo, $N_{\rm
ion}$ and (3) the mean free path of the ionizing photons within the IGM,
$R_{\rm mfp}$. We predict the accuracy with which these parameters can be
measured from future observations of the 21-cm power spectrum (PS) using the
upcoming SKA-Low. Unlike several earlier works, we account for the
non-Gaussianity of the inherent EoR 21-cm signal. Considering cosmic variance
only and assuming that foregrounds are completely removed, we find that
non-Gaussianity increases the volume of the $1 \sigma$ error ellipsoid of the
parameters by a factor of $133$ relative to the Gaussian predictions, the
orientation is also different. The ratio of the volume of error ellipsoids is
$1.65$ and $2.67$ for observation times of $1024$ and $10000$ hours
respectively, when all the $\mathbf{k}$ modes within the foreground wedge are
excluded. With foreground wedge excluded and for $1024$ hours, the 1D
marginalized errors are $(\Delta M_{\rm min}/M_{\rm min},\Delta N_{\rm
ion}/N_{\rm ion},\Delta R_{\rm mfp}/R_{\rm mfp})=(6.54, 2.71, 7.75) \times
10^{-2}$ which are respectively $2 \%$, $5 \%$ and $23 \%$ larger than the
respective Gaussian predictions. The impact of non-Gaussianity increases for
longer observations, and it is particularly important for $R_{\rm mfp}$.
