The H I intensity mapping bispectrum including observational effects
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Date
2021-07-30
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Abstract
The bispectrum is a three-point statistic with the potential to provide additional information beyond power spectra analyses of
survey data sets. Radio telescopes that broadly survey the 21-cm emission from neutral hydrogen (H I) are a promising way to
probe LSS and in this work we present an investigation into the H I intensity mapping (IM) bispectrum using simulations. We
present a model of the redshift space H I IM bispectrum including observational effects from the radio telescope beam and 21-cm
foreground contamination. We validate our modelling prescriptions with measurements from robust IM simulations, inclusive
of these observational effects. Our foreground simulations include polarization leakage, on which we use a principal component
analysis cleaning method. We also investigate the effects from a non-Gaussian beam including side-lobes. For a MeerKAT-like
single-dish IM survey at z = 0.39, we find that foreground removal causes an 8 per cent reduction in the equilateral bispectrum’s
signal-to-noise ratio, whereas the beam reduces it by 62 per cent. We find our models perform well, generally providing χ2
dof ∼ 1,
indicating a good fit to the data. Whilst our focus is on post-reionization, single-dish IM, our modelling of observational effects,
especially foreground removal, can also be relevant to interferometers and reionization studies.
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Keywords
data analysis – methods, statistical – cosmology, observations – cosmology, Methods
Citation
Cunnington. (2021). The H i intensity mapping bispectrum including observational effects. Monthly Notices of the Royal Astronomical Society., 507(2), 1623–1639. https://doi.org/10.1093/mnras/stab2200