Abstract
We provide perturbation theory predictions for the HI intensity mapping power
spectrum multipoles using the Effective Field Theory of Large Scale Structure
(EFTofLSS), which should allow us to constrain cosmological parameters
exploiting mildly nonlinear scales. Assuming survey specifications typical of
proposed interferometric HI intensity mapping experiments like CHORD and PUMA,
and realistic ranges of validity for the perturbation theory modelling, we run
mock full shape MCMC analyses at a redshift bin centred at $z=0.5$, and compare
with Stage-IV optical galaxy surveys. We include the impact of 21cm foreground
removal using simulations-based prescriptions, and quantify the effects on the
precision and accuracy of the parameter estimation. We vary 10 parameters in
total: 3 cosmological and 7 bias and counterterms parameters. Amongst them, the
4 parameters of interest are: the cold dark matter density, $ømega_c$, the
Hubble parameter, $h$, the primordial amplitude of the power spectrum, $A_s$,
and the linear HI bias, $b_1$. For the best case scenario, we obtain unbiased
constraints on all parameters with $<3\%$ errors at $68\%$ confidence level.
When we include the foreground removal effects, the parameter estimation
becomes strongly biased, with all parameters being $>5\sigma$ away from the
true values. We find that scale cuts $k_min 0.03 \, h/Mpc$ are required
to return accurate estimates for $ømega_c$ and $h$, at the price of a
decrease in the precision, while $A_s$ and $b_1$ remain biased. We comment on
the implications of these results for current and forthcoming real data
analyses.
Description
Interferometric HI intensity mapping: perturbation theory predictions and foreground removal effects
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