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Title: Probing patchy reionization through τ-21 cm correlation statistics

We consider the cross-correlation between free electrons and neutral hydrogen during the epoch of reionization (EoR). The free electrons are traced by the optical depth to reionization τ, while the neutral hydrogen can be observed through 21 cm photon emission. As expected, this correlation is sensitive to the detailed physics of reionization. Foremost, if reionization occurs through the merger of relatively large halos hosting an ionizing source, the free electrons and neutral hydrogen are anticorrelated for most of the reionization history. A positive contribution to the correlation can occur when the halos that can form an ionizing source are small. A measurement of this sign change in the cross-correlation could help disentangle the bias and the ionization history. We estimate the signal-to-noise ratio of the cross-correlation using the estimator for inhomogeneous reionization τ-hat {sub ℓm} proposed by Dvorkin and Smith. We find that with upcoming radio interferometers and cosmic microwave background (CMB) experiments, the cross-correlation is measurable going up to multipoles ℓ ∼ 1000. We also derive parameter constraints and conclude that, despite the foregrounds, the cross-correlation provides a complementary measurement of the EoR parameters to the 21 cm and CMB polarization autocorrelations expected to be observed in the comingmore » decade.« less
Authors:
;  [1] ;  [2]
  1. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08540 (United States)
  2. Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
Publication Date:
OSTI Identifier:
22348460
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 779; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BACKGROUND RADIATION; CORRELATIONS; COSMOLOGY; ELECTRONS; HYDROGEN; INTERFEROMETERS; LIMITING VALUES; MULTIPOLES; PHOTON EMISSION; POLARIZATION; RELICT RADIATION; SIGNAL-TO-NOISE RATIO; STARS