Munshi, D. and Corasaniti, P.S. and Coles, Peter and Heavens, A.F. and Pandolfi, S. (2014) Reionization and CMB non-Gaussianity. Monthly Notices of the Royal Astronomical Society, 442 (4). pp. 821-837. ISSN 0035-8711

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Abstract

We show how cross-correlating a high-redshift external tracer field, such as the 21-cm neutral hydrogen distribution and product maps involving cosmic microwave background (CMB) temperature and polarization fields, that probe mixed bispectrum involving these fields, can help to determine the reionization history of the Universe, beyond what can be achieved from cross-spectrum analysis. Taking clues from recent studies for the detection of primordial non-Gaussianity, we develop a set of estimators that can study reionization using a power spectrum associated with the bispectrum (or skew-spectrum). We use the matched filtering inherent in this method to investigate different reionization histories. We check to what extent they can be used to rule out various models of reionization and study cross-contamination from different sources such as the lensing of the CMB. The estimators can be fine-tuned to optimize study of a specific reionization history. We consider three different types of tracers in our study, namely: proto-galaxies; 21-cm maps of neutral hydrogen; and quasars. We also consider four alternative models of reionization. We find that the cumulative signal-to-noise ratio (S/N) for detection at ℓmax = 2000 can reach O(70) for cosmic variance limited all-sky experiments. Combining 100 GHz, 143 GHz and 217 GHz channels of the Planck experiment, we find that the S/N lies in the range O(5)–O(35)⁠. The S/N depends on the specific choice of a tracer field, and multiple tracers can be effectively used to map out the entire reionization history with reasonable S/N. Contamination from weak lensing is investigated and found to be negligible, and the effects of Thomson scattering from patchy reionization are also considered.

Item Type:	Article
Keywords:	methods: analytical; methods: numerical; methods: statistical; dark ages; reionization; first stars; diffuse radiation; large-scale structure of Universe;
Academic Unit:	Faculty of Science and Engineering > Theoretical Physics
Item ID:	12506
Identification Number:	https://doi.org/10.1093/mnras/stu1123
Depositing User:	Peter Coles
Date Deposited:	03 Mar 2020 16:57
Journal or Publication Title:	Monthly Notices of the Royal Astronomical Society
Publisher:	The Royal Astronomical Society
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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