Power spectrum multipole expansion for H <scp>i</scp> intensity mapping experiments: unbiased parameter estimation

We assess the performance of multipole expansion formalism in case single-dish HI intensity mapping, including instrumental and foreground removal effects. This is used to provide MCMC forecasts for a range cosmological parameters, redshift space distortions Alcock-Paczynski effect. first determine validity our power spectrum modelling by fitting simulation data, concentrating on monopole, quadrupole, hexadecapole contributions. then show that subtraction effects can lead severe biases determination particular parameters relating transverse BAO rescaling, growth rate bias ($\alpha_\perp$, $\overline{T}_\text{HI} f\sigma_8$, b_\text{HI} \sigma_8$, respectively). attempt account these constructing 2-parameter prescription, find prescription leads unbiased parameter estimation at expense increasing estimated uncertainties parameters. In addition, we confirm significantly impact theoretical covariance matrix, cause between different multipoles become non-negligible. Finally, effect higher-order analysis, how be investigate presence systematic mapping data.