Modes of the Dark Ages 21cm field accessible to a lunar radio interferometer

Abstract

At redshifts beyond $z\gtrsim 30$, the 21cm line from neutral hydrogen is expected to be essentially the only viable probe of the 3D matter distribution. The lunar far-side is an extremely appealing site for future radio arrays that target this signal, as it is protected from terrestrial radio frequency interference, and has no ionosphere to attenuate and absorb radio emission at low frequencies (tens of MHz and below). We forecast the sensitivity of low-frequency lunar radio arrays to the bispectrum of the 21cm brightness temperature field, which can in turn be used to probe primordial non-Gaussianity generated by particular early universe models. We account for the loss of particular regions of Fourier space due to instrumental limitations and systematic effects, and predict the sensitivity of different representative array designs to local-type non-Gaussianity in the bispectrum, parametrised by $f_{\mathrm{NL}}$. Under the most optimistic assumption of sample variance-limited observations, we find that $\sigma (f_{\mathrm{NL}})\lesssim 0.01$ could be achieved for several broad redshift bins at $z\gtrsim 30$ if foregrounds can be removed effectively. These values degrade to between $\sigma (f_{\mathrm{NL}})\sim 0.03$ and $0.7$ for $z=30$ to $z=170$ respectively when a large foreground wedge region is excluded.

14 pages, 5 figures, published as part of Phil. Trans. R. Soc. A discussion meeting issue "Astronomy from the Moon: the next decades (part 2)"

References in corpus (12)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Primordial Non-Gaussianities from Inflation Models
• Evolution of the 21 cm signal throughout cosmic history
• The bispectrum of redshifted 21-cm fluctuations from the dark ages
• The halo model for cosmology: a pedagogical review
• Toward a robust inference method for the galaxy bispectrum: likelihood function and model selection
• Forecasts on Primordial non-Gaussianity from 21 cm Intensity Mapping experiments
• Prospects for precision cosmology with the 21 cm signal from the dark ages
• The Dark Ages' 21-cm Trispectrum
• Constraining primordial non-Gaussianity by combining next-generation galaxy and 21 cm intensity mapping surveys
• The limits of cosmology: role of the Moon