期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 487, 期 4, 页码 4951-4964出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stz1561
关键词
large-scale structure of universe; first stars; cosmology: reionization; diffuse radiation; methods: statistical; technique: interferometric
资金
- Science and Technology Facilities Council [ST/F002858/1, ST/I000976/1]
- Southeast Physics Network (SEPNet)
Recent simulations show the Epoch of Reionization (EoR) 21-cm signalto be inherently non-Gaussian whereby the error covariance matrix of the 21-cm power spectrum (PS) contains a trispectrum contribution that would be absent if the signal were Gaussian. Using the binned power spectrum and trispectrum from simulations, here we present a methodology for incorporating these with the baseline distribution and system noise to make error predictions for observations with any radio-interferometric array. Here we consider the upcoming SKA-Low. Non-Gaussianity enhances the errors introducing a positive deviation Delta relative to the Gaussian predictions. Delta increases with observation time t(obs) and saturates as the errors approach the cosmic variance. Considering t(obs)= 1024 hours where a 5 sigma detection is possible at all redshifts 7 <= z <= 13, in the absence of foregrounds we find that the deviations are important at small k where we have at for some of the redshifts and also at intermediate where we have at z= 7. Non-Gaussianity also introduces correlations between the errors in different k bins, and we find both correlations and anticorrelations with the correlation coefficient value spanning -0.4 <= r(ij)<= 0.8. Incorporating the foreground wedge, Delta continues to be important () at z= 7. We conclude that non-Gaussianity makes a significant contribution to the errors and this is important in the context of the future instruments that aim to achieve high-sensitivity measurements of the EoR 21-cm PS.
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