Simulations for single-dish intensity mapping experiments

M-A Bigot-Sazy, C Dickinson, Richard A Battye, I W A Browne, Y-Z Ma, Bruno Maffei, F Noviello, M Remazeilles, P N Wilkinson

    Research output: Contribution to journalArticlepeer-review


    H I intensity mapping is an emerging tool to probe dark energy. Observations of the redshifted H I signal will be contaminated by instrumental noise, atmospheric and Galactic foregrounds. The latter is expected to be four orders of magnitude brighter than the H I emission we wish to detect. We present a simulation of single-dish observations including an instrumental noise model with 1/f and white noise, and sky emission with a diffuse Galactic foreground and H I emission. We consider two foreground cleaning methods: spectral parametric fitting and principal component analysis. For a smooth frequency spectrum of the foreground and instrumental effects, we find that the parametric fitting method provides residuals that are still contaminated by foreground and 1/f noise, but the principal component analysis can remove this contamination down to the thermal noise level. This method is robust for a range of different models of foreground and noise, and so constitutes a promising way to recover the H I signal from the data. However, it induces a leakage of the cosmological signal into the subtracted foreground of around 5 per cent. The efficiency of the component separation methods depends heavily on the smoothness of the frequency spectrum of the foreground and the 1/f noise. We find that as long as the spectral variations over the band are slow compared to the channel width, the foreground cleaning method still works.
    Original languageEnglish
    Pages (from-to)3240-3253
    Number of pages14
    JournalMonthly Notices of the Royal Astronomical Society
    Publication statusPublished - 2015


    • methods: statistical
    • cosmology: observations
    • diffuse radiation
    • radio continuum: general
    • radio lines: galaxies
    • radio lines: ISM


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