Upper Limits on the 21 cm Power Spectrum at z = 5.9 from Quasar Absorption Line Spectroscopy

Abstract

We present upper limits on the 21 cm power spectrum at $z=5.9$ calculated from the model-independent limit on the neutral fraction of the intergalactic medium of $x_{\mathrm{H}\mathrm{I}}<0.06+0.05(1\sigma )$ derived from dark pixel statistics of quasar absorption spectra. Using 21CMMC, a Markov chain Monte Carlo Epoch of Reionization analysis code, we explore the probability distribution of 21 cm power spectra consistent with this constraint on the neutral fraction. We present 99 per cent confidence upper limits of ${\Delta }^2(k)<10$ to $20{\mathrm{mK}}^2$ over a range of $k$ from 0.5 to $2.0h{\mathrm{Mpc}}^{-1}$, with the exact limit dependent on the sampled $k$ mode. This limit can be used as a null test for 21 cm experiments: a detection of power at $z=5.9$ in excess of this value is highly suggestive of residual foreground contamination or other systematic errors affecting the analysis.

5 pages, 1 figure, accepted to MNRAS letters

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Cited by in corpus (4)

• Improving the Epoch of Reionization Power Spectrum Results from Murchison Widefield Array Season 1 Observations
• First Season MWA Phase II EoR Power Spectrum Results at Redshift 7
• The impact of non-Gaussianity on the error covariance for observations of the Epoch of Reionization 21-cm power spectrum
• Analysing the Epoch of Reionization with three-point correlation functions and machine learning techniques