Imaging Large Scale HI structure

GBT_LargeScale_HI.pngThe large-scale distribution of neutral hydrogen in the Universe will be luminous through its 21 cm emission. Switzer et al. use data acquired with the GBT that span the redshift range 0.6 < z < 1.0 to detect, for the first time, the auto-power spectrum of 21 cm intensity fluctuations and constrain neutral hydrogen fluctuations at z ∼ 0.8. The synchrotron foregrounds exceed the signal by 103, but have fewer degrees of freedom and can be removed efficiently. Through a Bayesian treatment of signal and foregrounds, they derive an HI baryon density ΩHI bHI= [0.62+0.23-0.15] × 10-3 at 68 per cent confidence, where ΩHI is the neutral hydrogen (H I) fraction of the cosmic closure density, and bHI is the H I bias parameter.

View Publication: Determination of z ~ 0.8 Neutral Hydrogen Fluctuations Using the 21 cm Intensity Mapping Autocorrelation, E.R. Switzer (CITA), K.W. Masui (CITA, Toronto), K. Bandura (McGill), L.-M. Calin (CITA), T.-C. Chang (ASIAA), X.-L. Chen (NAO-CAS, Peking), Y.-C. Li (NAO-CAS), Y.-W. Liao (ASIAA), A. Natarajan (Carnegie Mellon), U.-L. Pen (CITA), J.B. Peterson (Carnegie Mellon), J.R. Shaw (CITA), and T.C. Voytek (Carnegie Mellon), 2013 MNRAS, 434, L46 (1 September 2013).

Added 21 Jan 2014

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