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Non-Gaussianity from self-ordering scalar fields

Figueroa, Daniel G. and Caldwell, Robert R. and Kamionkowski, Marc (2010) Non-Gaussianity from self-ordering scalar fields. Physical Review D, 81 (12). Art. No. 123504 . ISSN 0556-2821. http://resolver.caltech.edu/CaltechAUTHORS:20100625-080640927

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Abstract

The Universe may harbor relics of the post-inflationary epoch in the form of a network of self-ordered scalar fields. Such fossils, while consistent with current cosmological data at trace levels, may leave too weak an imprint on the cosmic microwave background and the large-scale distribution of matter to allow for direct detection. The non-Gaussian statistics of the density perturbations induced by these fields, however, permit a direct means to probe for these relics. Here we calculate the bispectrum that arises in models of self-ordered scalar fields. We find a compact analytic expression for the bispectrum, evaluate it numerically, and provide a simple approximation that may be useful for data analysis. The bispectrum is largest for triangles that are aligned (have edges k_1≃2k_2≃2k_3) as opposed to the local-model bispectrum, which peaks for squeezed triangles (k_1≃k_2≫k_3), and the equilateral bispectrum, which peaks at k_1≃k_2≃k_3. We estimate that this non-Gaussianity should be detectable by the Planck satellite if the contribution from self-ordering scalar fields to primordial perturbations is near the current upper limit.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1103/PhysRevD.81.123504 DOIUNSPECIFIED
http://prd.aps.org/abstract/PRD/v81/i12/e123504PublisherUNSPECIFIED
Additional Information:© 2010 The American Physical Society. Received 2 March 2010; published 4 June 2010. DGF thanks Caltech and CERN for hospitality during the completion of this work. DGF was supported by the Spanish Ministry of Science under Contract No. AP-2005- 1092. This work was supported at Caltech by DOE under Contract No. DE-FG03-92-ER40701 and the Gordon and Betty Moore Foundation, and at Dartmouth by NSF under Contract No. AST-0349213.
Group:TAPIR
Funders:
Funding AgencyGrant Number
Spanish Ministry of Science AP-2005-1092
Department of Energy (DOE)DE-FG03-92-ER40701
Gordon and Betty Moore Foundation UNSPECIFIED
NSFAST-0349213
Classification Code:PACS: 98.80.-k, 11.30.Fs, 98.80.Cq
Record Number:CaltechAUTHORS:20100625-080640927
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20100625-080640927
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18808
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:09 Jul 2010 22:50
Last Modified:26 Dec 2012 12:10

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