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Open AccessJournal ArticleDOI

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

TLDR
In this paper, the authors used the auto-power spectrum of 21 cm intensity fluctuations to constrain neutral hydrogen fluctuations at z~0.8, where the dominant synchrotron foregrounds exceed the signal by 10^3 and can be removed efficiently.
Abstract
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.

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Journal ArticleDOI

Late-time cosmology with 21cm intensity mapping experiments

TL;DR: In this paper, the authors present a framework for forecasting cosmological constraints from future neutral hydrogen intensity mapping experiments at low to intermediate redshifts, and establish a simple way of comparing such surveys with optical galaxy redshift surveys.
Journal ArticleDOI

Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies

Elcio Abdalla, +202 more
TL;DR: In this paper , the authors focus on the 5.0σ tension between the Planck CMB estimate of the Hubble constant H0 and the SH0ES collaboration measurements and discuss the importance of trying to fit a full array of data with a single model.
Book

Inflation Physics from the Cosmic Microwave Background and Large Scale Structure.

TL;DR: For example, a future CMB and large-scale structure (LSS) experiments are poised to test the leading paradigm for these earliest moments and to detect the imprints of the inflationary epoch, thereby dramatically increasing our understanding of fundamental physics and the early universe.
Journal ArticleDOI

New Limits on 21cm EoR From PAPER-32 Consistent with an X-Ray Heated IGM at z=7.7

TL;DR: In this article, the authors present new constraints on the 21cm EoR power spectrum derived from 3 months of observing with a 32-antenna, dual-polarization deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa.
References
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Journal ArticleDOI

Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation

TL;DR: In this paper, the authors show that the tensor-to-scalar ratio r 1 is disfavored regardless of r. They provide a set of "WMAP distance priors, to test a variety of dark energy models.
Journal ArticleDOI

Damped Lyα Systems at z < 1.65: The Expanded Sloan Digital Sky Survey Hubble Space Telescope Sample

TL;DR: In this paper, the authors present results of the Cycle 11 survey for low-redshift (z 0.5 to 0.6 ) and show that the mean H I column density of Mg II systems with 0.3 is nDLA(z) = n0(1 + z), where n0 = 0.044? 0.005 and? = 1.1?.
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