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Publication . Preprint . Article . 2017 . Embargo end date: 01 Jan 2016

Constraining cosmological ultra-large scale structure using numerical relativity

Jonathan Braden; Matthew C. Johnson; Hiranya V. Peiris; Anthony Aguirre;
Open Access
Published: 31 Jul 2017
Publisher: arXiv
Country: United Kingdom
Abstract
Cosmic inflation, a period of accelerated expansion in the early universe, can give rise to large amplitude ultra-large scale inhomogeneities on distance scales comparable to or larger than the observable universe. The cosmic microwave background (CMB) anisotropy on the largest angular scales is sensitive to such inhomogeneities and can be used to constrain the presence of ultra-large scale structure (ULSS). We numerically evolve nonlinear inhomogeneities present at the beginning of inflation in full General Relativity to assess the CMB quadrupole constraint on the amplitude of the initial fluctuations and the size of the observable universe relative to a length scale characterizing the ULSS. To obtain a statistically significant number of simulations, we adopt a toy model in which inhomogeneities are injected along a preferred direction. We compute the likelihood function for the CMB quadrupole including both ULSS and the standard quantum fluctuations produced during inflation. We compute the posterior given the observed CMB quadrupole, finding that when including gravitational nonlinearities, ULSS curvature perturbations of order unity are allowed by the data, even on length scales not too much larger than the size of the observable universe. Our results illustrate the utility and importance of numerical relativity for constraining early universe cosmology.
Comment: 14 pages, 6 figures v3: Clarifications added regarding the generality of results - conclusions unchanged, version accepted for publication in PRD, v2: updated with minor clarifications, submitted
Subjects by Vocabulary

arXiv: Astrophysics::Cosmology and Extragalactic Astrophysics

Microsoft Academic Graph classification: Observable universe Metric expansion of space Inflation (cosmology) De Sitter universe Universe media_common.quotation_subject media_common Particle horizon Cosmic microwave background Big Bang Physics Astrophysics

Subjects

Cosmology and Nongalactic Astrophysics (astro-ph.CO), General Relativity and Quantum Cosmology (gr-qc), High Energy Physics - Theory (hep-th), FOS: Physical sciences, Evolution of the Universe, Fluids & classical fields in curved spacetime, Inflation, Relativistic aspects of cosmology,Astrophysical & cosmological simulations, Numerical relativity, Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology, High Energy Physics - Theory

Funded by
NSERC
Project
  • Funder: Natural Sciences and Engineering Research Council of Canada (NSERC)
,
NSF| Programs on Critical Problems in Physics, Astrophysics and Biophysics at the Aspen Center for Physics
Project
  • Funder: National Science Foundation (NSF)
  • Project Code: 1066293
  • Funding stream: Directorate for Mathematical & Physical Sciences | Division of Physics
,
EC| COSMICDAWN
Project
COSMICDAWN
Understanding the Origin of Cosmic Structure
  • Funder: European Commission (EC)
  • Project Code: 306478
  • Funding stream: FP7 | SP2 | ERC
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