Reaching small scales with low frequency imaging: applications to the Dark Ages

Abstract

The initial conditions for the density perturbations in the early Universe, which dictate the large scale structure and distribution of galaxies we see today, are set during inflation. Measurements of primordial non-Gaussianity are crucial for distinguishing between different inflationary models. Current measurements of the matter power spectrum from the CMB only constrain this on scales up to $k\sim 0.1$ Mpc${}^{-1}$. Reaching smaller angular scales (higher values of $k$) can provide new constraints on non-Gaussianity. A powerful way to do this is by measuring the $\text{H}\text{I}$ matter power spectrum at $z\gtrsim 30$. In this paper, we investigate what values of $k$ can be reached for the LOw Frequency ARray (LOFAR), which can achieve $\lesssim$1${}^{\prime \prime }$ resolution at $\sim$50 MHz. Combining this with a technique to isolate the spectrally smooth foregrounds to a wedge in $k_{\parallel }$ - $k_{\perp }$ space, we demonstrate what values of $k$ we can feasibly reach within observational constraints. We find that LOFAR is $\sim$5 orders of magnitude away from the desired sensitivity, for 10 years of integration time.

11 pages, 3 figures, accepted for publication in Royal Society Philosophical Transactions A. Under media embargo until publication

References in corpus (9)

• Late-time cosmology with 21cm intensity mapping experiments
• Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\mathbf{z}\approx 9.1$ from LOFAR
• The Epoch of Reionization Window: II. Statistical Methods for Foreground Wedge Reduction
• First Season MWA EoR Power Spectrum Results at Redshift 7
• Science with a lunar low-frequency array: from the dark ages of the Universe to nearby exoplanets
• Results from EDGES High-Band: I. Constraints on Phenomenological Models for the Global $21$ cm Signal
• Subarcsecond international LOFAR radio images of the M82 nucleus at 118 MHz and 154 MHz
• Astro 2020 Science White Paper: Fundamental Cosmology in the Dark Ages with 21-cm Line Fluctuations
• Small-scale primordial fluctuations in the 21cm Dark Ages signal

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