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Simulations for single-dish intensity mapping experiments
Bigot-Sazy, M-A; Dickinson, C; Battye, R A; Browne, I W A; Ma, Y-Z; Maffei, B; Noviello, F; Remazeilles, M; Wilkinson, P N
Monthly Notices of the Royal Astronomical Society. 2015;454:3240-3253.
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Abstract
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.
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cosmology: observations; diffuse radiation; methods: statistical; radio continuum: general; radio lines: ISM; radio lines: galaxies
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- Related website http://adsabs.harvard.edu/abs/2015MNRAS.454.3240B