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Multipole expansion for HI intensity mapping experiments: simulations and modelling

Research output: Contribution to journalArticlepeer-review

  • Steven Cunnington
  • Alkistis Pourtsidou
  • Paula S. Soares
  • Chris Blake
  • Dr David Bacon
We present a framework and an open-source python toolkit to analyse the 2-point statistics of 3D fluctuations in the context of HI intensity maps using the multipole expansion formalism. We include simulations of the cosmological HI signal using N-body and log-normal methods, foregrounds and their removal, as well as instrumental effects. Using these simulations and analytical modelling, we investigate the impact of foreground cleaning and the instrumental beam on the power spectrum multipoles as well as on the Fourier space clustering wedges. We find that both the instrumental beam and the foreground removal can produce a quadrupole (and a hexadecapole) signal, and demonstrate the importance of controlling and accurately modelling these effects for precision radio cosmology. We conclude that these effects can be modelled with reasonable accuracy using our multipole expansion technique. We also perform an MCMC analysis to showcase the effect of foreground cleaning on the estimation of the HI abundance and bias parameters. The accompanying python toolkit is available at https://github.com/IntensityTools/MultipoleExpansion, and includes an interactive suite of examples to aid new users.
Original languageEnglish
Pages (from-to)415-433
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Volume496
Issue number1
Early online date3 Jun 2020
DOIs
Publication statusPublished - 1 Jul 2020

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    Rights statement: This article has been accepted for publication in MNRAS © 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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