http://arxiv.org/abs/2111.11347
Cosmological parameter estimation in the post-reionisation era via the radio emission of neutral hydrogen ($\text{\hi}$), is one of the key science goals of the forthcoming SKA Observatory (SKAO). In this paper, we explore detection capability for baryon acoustic oscillations (BAO) with a SKAO-like experimental set up, using a suite of (100) simulations inclusive of the main limitations from foreground contamination and poor angular resolution caused by the radio telescope beam. The latter represents a serious challenge for BAO detection with \hi\ intensity mapping, hence we investigate adopting a multipole expansion approach as a means for mitigating the BAO detection limitations caused by the broad single-dish beam. We also showcase the gains made from cross-correlating the \hi\ intensity mapping data with an overlapping spectroscopic galaxy survey, aiming to test the potential synergies between the SKA Project and other future cosmological experiments at optical/near-infrared wavelengths, like the \textit{Euclid} satellite or the Dark Energy Spectroscopic Instrument. Whilst we were still able to achieve a $\sim4.5\sigma$ detection of BAO features in auto-correlation despite the dominant beam effect, a cross-correlation can increase this to a $\sim6\sigma$ detection. Furthermore, by adopting the widely studied multipole expansion formalism, we show that including the power spectrum quadrupole besides the monopole in a joint fit can approximately double the BAO detection significance. Despite not implementing a radial-only $P(k_\parallel)$ analysis in favour of the three-dimensional $P(\bm{k})$ and its multipoles, we were still able to obtain robust constraints on the radial Alcock-Paczynski parameter, but found that perpendicular parameter remains unconstrained and prior dominated due to beam effects.
A. Rubiola, S. Cunnington and S. Camera
Tue, 23 Nov 21
78/84
Comments: 18 pages, 13 figures
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