Searching for oscillations in the primordial power spectrum. II. Constraints from Planck data

P. Daniel Meerburg, David N. Spergel, and Benjamin D. Wandelt
Phys. Rev. D 89, 063537 – Published 28 March 2014

Abstract

In this second of two papers we apply our recently developed code to search for resonance features in the Planck CMB temperature data. We search both for log-spaced oscillations or linear-spaced oscillations and compare our findings with results of our WMAP9 analysis and the Planck team analysis [P. A. R. Ade et al. (Planck Collaboration), arXiv:1303.5082]. While there are hints of log-spaced resonant features present in the WMAP9 data, the significance of these features weaken with more data. With more accurate small scale measurements, we also find that the best-fit frequency has shifted and the amplitude has been reduced. We confirm the presence of a several low frequency peaks, earlier identified by the Planck team, but with a better improvement of fit (Δχeff212). We further investigate this improvement by allowing the lensing potential to vary as well, showing mild correlation between the amplitude of the oscillations and the lensing amplitude. We find that the improvement of the fit increases even more (Δχeff214) for the low frequencies that modify the spectrum in a way that mimics the lensing effect. Since these features were not present in the WMAP data, they are primarily due to better measurements of Planck at small angular scales. For linear-spaced oscillations we find a maximum Δχeff213 scanning two orders of magnitude in frequency space, and the biggest improvements are at extremely high frequencies. Again, we recover a best-fit frequency very close to the one found in WMAP9, which confirms that the fit improvement is driven by low . Further comparisons with WMAP9 show Planck contains many more features, both for linear- and log-spaced oscillations, but with a smaller improvement of fit. We discuss the improvement as a function of the number of modes and study the effect of the 217 GHz map, which appears to drive most of the improvement for log-spaced oscillations. Two points strongly suggest that the detected features are fitting a combination of the noise and the dip at 1800 in the 217 GHz map: the fit improvement mostly comes from a small range of , and comparison with simulations shows that the fit improvement is consistent with a statistical fluctuation. We conclude that none of the detected features are statistically significant.

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  • Received 8 November 2013

DOI:https://doi.org/10.1103/PhysRevD.89.063537

© 2014 American Physical Society

Authors & Affiliations

P. Daniel Meerburg1,*, David N. Spergel1,†, and Benjamin D. Wandelt2,3,‡

  • 1Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
  • 2CNRS-UPMC Université Paris 06, UMR7095, Institut d‘Astrophysique de Paris, 98bis Boulevard Arago, F-75014 Paris, France
  • 3Departments of Physics and Astronomy, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA

  • *meerburg@princeton.edu
  • dns@astro.princeton.edu
  • wandelt@iap.fr

See Also

Searching for oscillations in the primordial power spectrum. I. Perturbative approach

P. Daniel Meerburg, David N. Spergel, and Benjamin D. Wandelt
Phys. Rev. D 89, 063536 (2014)

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Vol. 89, Iss. 6 — 15 March 2014

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