Searching for standard clocks in the primordial universe

Journal Article · Wed Aug 01 04:00:00 EDT 2012 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2012/08/014· OSTI ID:22279914

Chen, Xingang ^[1]; Ringeval, Christophe ^[2]

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1. Centre for Theoretical Cosmology, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA (United Kingdom)
2. Centre for Cosmology, Particle Physics and Phenomenology, Institute of Mathematics and Physics, Louvain University, 2 Chemin du Cyclotron, 1348 Louvain-la-Neuve (Belgium)

Classically oscillating massive fields can be used as ''standard clocks'' in the primordial universe. They generate features in primordial density perturbations that directly record the scale factor evolution a(t). Detecting and measuring these ''fingerprint'' signals is challenging but would provide a direct evidence for a specific primordial universe paradigm. In this paper, such a search is performed for the power spectrum of the Cosmic Microwave Background (CMB) anisotropies using the WMAP7 data. Although a good fit to the data privileges a scale around k = 0.01 Mpc{sup −1}, we do not find statistical significance for, neither against, the presence of any feature. We then forecast the expected constraints a Planck-like CMB experiment can impose on the fingerprint parameters by using Markov-Chain-Monte-Carlo (MCMC) methods on mock data. We exhibit a high sensitivity zone for wavenumbers ranging from 0.01 Mpc{sup −1} to 0.1 Mpc{sup −1} in which fingerprints show up first on the posterior probability distribution of the wavenumber at which they occur, and then on the modulation frequency. Within the sensitivity zone, we show that the inflationary paradigm can be inferred from a single feature generating at least a 20% modulation of the primordial power spectrum. This minimal value sensitively depends on the modulation frequency.

• OSTI ID: 22279914
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 08 Vol. 2012; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANISOTROPY
ASTROPHYSICS
COSMOLOGY
DENSITY
DISTURBANCES
ENERGY SPECTRA
EVOLUTION
MARKOV PROCESS
MODULATION
MONTE CARLO METHOD
PROBABILITY
RELICT RADIATION
SENSITIVITY
UNIVERSE