Determination of z ∼ 0.8 neutral hydrogen fluctuations using the 21 cm intensity mapping autocorrelation

By E. Switzer, K. Masui, K. Bandura, L.-M. Calin, T. Chang, Xuelei Chen, Yin-Bi Li, Yu-Wei Liao, A. Natarajan, Ue-Li Pen and 3 more. 2013

210 citations recorded by the source corpus.

The large-scale distribution of neutral hydrogen in the Universe will be luminous through its 21 cm emission. Here, for the first time, we use the auto-power spectrum of 21 cm intensity fluctuations to constrain neutral hydrogen fluctuations at z~0.8. Our data were acquired with the Green Bank Telescope and span the redshift range 0.6 < z < 1 over two fields totalling ~41 deg. sq. and 190 h of radio integration time. The dominant synchrotron foregrounds exceed the signal by ~10^3, but have fewer degrees of freedom and can be removed efficiently. Even in the presence of residual foregrounds, the auto-power can still be interpreted as an upper bound on the 21 cm signal. Our previous measurements of the cross-correlation of 21 cm intensity and the WiggleZ galaxy survey provide a lower bound. Through a Bayesian treatment of signal and foregrounds, we can combine both fields in auto- and cross-power into a measurement of Omega_HI b_HI = [0.62^{+0.23}_{-0.15}] * 10^{-3} at 68% confidence with 9% systematic calibration uncertainty, where Omega_HI is the neutral hydrogen (HI) fraction and b_HI is the HI bias parameter. We describe observational challenges with the present data set and plans to overcome them.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7e07532d8b4bca9c403ca5c1cb4ea1ba21b5bc5c

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Citations in the corpus

Cosmology with Phase 1 of the Square Kilometre Array Red Book 2018: Technical specifications and performance forecasts (2018, methodology): “Measurements using the Green Bank Telescope (GBT) produced the first tentative detection of the cosmological HI intensity signal by cross-correlating with the WiggleZ redshift survey (Chang et al. 2010; Switzer et al. 2013; Masui et al. 2013a).”
New Limits on 21cm EoR From PAPER-32 Consistent with an X-Ray Heated IGM at z=7.7 (2013, methodology): “We use Monte Carlo simulations (see, e.g., Masui et al. 2013, Paciga et al. 2013, and Switzer et al. 2013) to estimate the expected signal attenuation through the analysis chain from §3.6 onward, as illustrated by the red data-flow path in Figure 2.”
LATE-TIME COSMOLOGY WITH 21 cm INTENSITY MAPPING EXPERIMENTS (2014, methodology): “Practical experience of foreground subtraction from real data is quite limited so far (see Chang et al. 2010; Masui et al. 2013; Switzer et al. 2013 for some initial attempts), and so we do not have a good picture of how important various aspects of the foreground problem are yet.”
An Overview of CHIME, the Canadian Hydrogen Intensity Mapping Experiment (2022, background): “A complementary way to map the large scale distribution of matter, called hydrogen intensity mapping, has been successfully demonstrated by several analyses (Pen et al. 2009; Chang et al. 2010; Masui et al. 2013; Switzer et al. 2013; Anderson et al. 2018; Wolz et al. 2021).”
HIRAX: a probe of dark energy and radio transients (2016, unknown): “Only upper bounds have been placed on the BAO contribution to the 21 cm auto-correlation power spectrum.(11)”