The Impact of Realistic Foreground and Instrument Models on 21cm Epoch
  of Reionization Experiments
  Predictions for the ability of 21-cm interferometric experiments to
discriminate Epoch of Reionization (EoR) signal models are typically limited by
the simplicity of data models, whereby foreground signals and characteristics
of the instrument are often simplified or neglected.To move towards more
realistic scenarios, we explore the effects of applying more realistic
foreground and instrument models to the 21cm signal, and the ability to
estimate astrophysical parameters with these additional complexities. We use a
highly-optimized version of \textsc{21cmFAST}, integrated into \textsc{21cmMC},
to generate lightcones of the brightness temperature fluctuation for Bayesian
parameter estimation. We include a statistical point-source foreground model
and an instrument model based on the Murchison Widefield Array (MWA) scaled in
observation time to have an effective sensitivity similar to the future Square
Kilometre Array (SKA). We also extend the current likelihood prescription to
account for the presence of beam convolution and foregrounds, the 2-Dimensional
Power Spectrum (PS), and the correlation of PS modes. We use frequency bands
between 150 and 180 MHz to constrain the ionizing efficiency ($\zeta$), the
minimum virial temperature of halos ($T_{\mathrm{vir}}$), the soft X-ray
emissivity per unit Star Formation Rate (SFR) ($L_X/SFR$ ), and the X-ray
energy threshold ($E_0$). We find that the inclusion of realistic foregrounds
and instrumental components biases the parameter constraints due to unaccounted
for cross-power between the EoR signal, foregrounds and thermal noise. This
causes estimates of $\zeta$ to be biased by up to $5\sigma$ but the estimates
of $T_{vir}$, L$_X$/SFR and E$_0$ remain unaffected and are all within
$1\sigma$.
