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Trispectrum of 21-cm background anisotropies as a probe of primordial non-Gaussianity

Cooray, Asantha and Li, Chao and Melchiorri, Alessandro (2008) Trispectrum of 21-cm background anisotropies as a probe of primordial non-Gaussianity. Physical Review D, 77 (10). Art. No. 103506. ISSN 0556-2821.

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The 21-cm anisotropies from the neutral hydrogen distribution prior to the era of reionization are a sensitive probe of primordial non-Gaussianity. Unlike the case with cosmic microwave background, 21-cm anisotropies provide multi-redshift information with frequency selection and are not damped at arcminute angular scales. We discuss the angular trispectrum of the 21-cm background anisotropies and discuss how the trispectrum signal generated by the primordial non-Gaussianity can be measured with the three-to-one correlator and the corresponding angular power spectrum. We also discuss the separation of primordial non-Gaussian information in the trispectrum with that generated by the subsequent nonlinear gravitational evolution of the density field. While with the angular bispectrum of 21-cm anisotropies one can limit the second-order corrections to the primordial fluctuations below fNL~1, using the trispectrum information we suggest that the third-order coupling term, f2 or gNL, can be constrained to be around 10 with future 21-cm observations over the redshift interval of 50 to 100.

Item Type:Article
Additional Information:©2008 The American Physical Society. (Received 22 January 2008; published 8 May 2008) This work was supported in part by NSF CAREER AST-0645427 at UC Irvine and by the Moore Foundation at Caltech. We thank David Lyth for motivating us to calculate the 21 cm trispectrum.
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ID Code:10492
Deposited By: Archive Administrator
Deposited On:09 May 2008
Last Modified:26 Dec 2012 10:01

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