The effect of non-Gaussianity on error predictions for the Epoch of Reionization (EoR) 21-cm power spectrum
2015 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 449, no 1, l41-L45 p.Article in journal (Refereed) Published
The Epoch of Reionization (EoR) 21-cm signal is expected to become increasingly non-Gaussian as reionization proceeds. We have used seminumerical simulations to study how this affects the error predictions for the EoR 21-cm power spectrum. We expect SNR = root N-k for a Gaussian random field where N-k is the number of Fourier modes in each k bin. We find that non-Gaussianity is important at high SNR where it imposes an upper limit [SNR](l). For a fixed volume V, it is not possible to achieve SNR > [SNR](l) even if N-k is increased. The value of [SNR](l) falls as reionization proceeds, dropping from similar to 500 at (x) over bar}(H1) = 0.15 for a [150.08 Mpc](3) simulation. We show that it is possible to interpret [SNR](l) in terms of the trispectrum, and we expect [SNR](l) proportional to root V if the volume is increased. For SNR << [SNR](l) we find SNR = root N-k/A with A similar to 0.95-1.75, roughly consistent with the Gaussian prediction. We present a fitting formula for the SNR as a function of N-k, with two parameters A and [SNR](l) that have to be determined using simulations. Our results are relevant for predicting the sensitivity of different instruments to measure the EoR 21-cm power spectrum, which till date have been largely based on the Gaussian assumption.
Place, publisher, year, edition, pages
2015. Vol. 449, no 1, l41-L45 p.
methods: statistical, cosmology: theory, dark ages, reionization, first stars, diffuse radiation
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-117437DOI: 10.1093/mnrasl/slv015ISI: 000353555000009OAI: oai:DiVA.org:su-117437DiVA: diva2:813280