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First observational tests of eternal inflation: Analysis methods and WMAP 7-year results

Feeney, Stephen M. and Johnson, Matthew C. and Mortlock, Daniel J. and Peiris, Hiranya V. (2011) First observational tests of eternal inflation: Analysis methods and WMAP 7-year results. Physical Review D, 84 (4). 043507. ISSN 2470-0010. doi:10.1103/PhysRevD.84.043507.

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In the picture of eternal inflation, our observable universe resides inside a single bubble nucleated from an inflating false vacuum. Many of the theories giving rise to eternal inflation predict that we have causal access to collisions with other bubble universes, providing an opportunity to confront these theories with observation. We present the results from the first observational search for the effects of bubble collisions, using cosmic microwave background data from the WMAP satellite. Our search targets a generic set of properties associated with a bubble-collision spacetime, which we describe in detail. We use a modular algorithm that is designed to avoid a posteriori selection effects, automatically picking out the most promising signals, performing a search for causal boundaries, and conducting a full Bayesian parameter estimation and model selection analysis. We outline each component of this algorithm, describing its response to simulated CMB skies with and without bubble collisions. Comparing the results for simulated bubble collisions to the results from an analysis of the WMAP 7-year data, we rule out bubble collisions over a range of parameter space. Our model selection results based on WMAP 7-year data do not warrant augmenting ΛCDM with bubble collisions. Data from the Planck satellite can be used to more definitively test the bubble-collision hypothesis.

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Johnson, Matthew C.0000-0002-5099-8185
Additional Information:© 2011 American Physical Society. Received 17 December 2010; published 8 August 2011. We are very grateful to Eiichiro Komatsu and the WMAP Science Team for supplying the end-to-end WMAP simulations used in our null tests. S. M. F. is supported by the Perren Fund. M. C. J. acknowledges support from the Moore Foundation. H.V. P. is supported by Marie Curie Grant No. MIRG-CT-2007-203314 from the European Commission, and by STFC and the Leverhulme Trust. M. C. J. and H.V. P. thank the Aspen Center for Physics, where this project was initiated, for hospitality. H.V. P. and D. J. M. acknowledge the hospitality of the Statistical Frontiers of Astrophysics workshop at IPMU, Tokyo. S. M. F. thanks Filipe Abdalla, Ingo Waldmann, and Michael Hirsch for useful discussions, and Jenny Feeney for proofreading the manuscript. M. C. J. thanks Rebecca Danos for discussions regarding the edge-detection algorithm. H. V. P. thanks Andrew Pontzen for interesting discussions regarding the general problem of CMB anomaly hunting. We acknowledge use of the HEALPIX package and the Legacy Archive for Microwave Background Data Analysis (LAMBDA). Support for LAMBDA is provided by the NASA Office of Space Science. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Research and Innovation. A preprint version of this paper presented only evidence ratios confined to patches. We thank an anonymous referee who encouraged us to develop this algorithm into a full-sky formalism. This calculation is now presented in Appendix and incorporated into our analysis pipeline and results.
Group:Caltech Theory
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Marie Curie Grant from the European CommissionMIRG-CT-2007-203314
Leverhulme TrustUNSPECIFIED
Government of Canada through Industry CanadaUNSPECIFIED
Province of Ontario Ministry of Research and InnovationUNSPECIFIED
Issue or Number:4
Classification Code:PACS: 98.80.Es, 98.70.Vc, 98.80.Cq
Record Number:CaltechAUTHORS:20110829-105838056
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25144
Deposited On:08 Sep 2011 20:19
Last Modified:09 Nov 2021 16:30

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