Issue |
A&A
Volume 566, June 2014
|
|
---|---|---|
Article Number | A77 | |
Number of page(s) | 10 | |
Section | Numerical methods and codes | |
DOI | https://doi.org/10.1051/0004-6361/201322326 | |
Published online | 30 June 2014 |
PRISM: Sparse recovery of the primordial power spectrum
Laboratoire AIM, UMR CEA-CNRS-Paris 7, Irfu, SAp, CEA Saclay,
91191
Gif sur Yvette Cedex,
France
e-mail: paniez.paykari@cea.fr; francois.lanusse@cea.fr
Received:
19
July
2013
Accepted:
2
March
2014
Aims. The primordial power spectrum describes the initial perturbations in the Universe which eventually grew into the large-scale structure we observe today, and thereby provides an indirect probe of inflation or other structure-formation mechanisms. Here, we introduce a new method to estimate this spectrum from the empirical power spectrum of cosmic microwave background maps.
Methods. A sparsity-based linear inversion method, named PRISM, is presented. This technique leverages a sparsity prior on features in the primordial power spectrum in a wavelet basis to regularise the inverse problem. This non-parametric approach does not assume a strong prior on the shape of the primordial power spectrum, yet is able to correctly reconstruct its global shape as well as localised features. These advantages make this method robust for detecting deviations from the currently favoured scale-invariant spectrum.
Results. We investigate the strength of this method on a set of WMAP nine-year simulated data for three types of primordial power spectra: a near scale-invariant spectrum, a spectrum with a small running of the spectral index, and a spectrum with a localised feature. This technique proves that it can easily detect deviations from a pure scale-invariant power spectrum and is suitable for distinguishing between simple models of the inflation. We process the WMAP nine-year data and find no significant departure from a near scale-invariant power spectrum with the spectral index ns = 0.972.
Conclusions. A high-resolution primordial power spectrum can be reconstructed with this technique, where any strong local deviations or small global deviations from a pure scale-invariant spectrum can easily be detected.
Key words: methods: statistical / cosmic background radiation / early Universe / inflation / methods: data analysis
© ESO, 2014
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.