General CMB and Primordial Bispectrum Estimation I: Mode Expansion, Map-Making and Measures of f_NL

Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

41 pages, 17 figures

Scientific paper

We present a detailed implementation of two bispectrum estimation methods which can be applied to general non-separable primordial and CMB bispectra. The method exploits bispectrum mode decompositions on the domain of allowed wavenumber or multipole values. Concrete mode examples constructed from symmetrised tetrahedral polynomials are given, demonstrating rapid convergence for known bispectra. We use these modes to generate simulated CMB maps of high resolution (l > 2000) given an arbitrary primordial power spectrum and bispectrum or an arbitrary late-time CMB angular power spectrum and bispectrum. By extracting coefficients for the same separable basis functions from an observational map, we are able to present an efficient and general f_NL estimator for a given theoretical model. The estimator has two versions comparing theoretical and observed coefficients at either primordial or late times, thus encompassing a wider range of models, including secondary anisotropies, lensing and cosmic strings. We provide examples and validation of both f_NL estimation methods by direct comparison with simulations in a WMAP-realistic context. In addition, we show how the full bispectrum can be extracted from observational maps using these mode expansions, irrespective of the theoretical model under study. We also propose a universal definition of the bispectrum parameter F_NL for more consistent comparison between theoretical models. We obtain WMAP5 estimates of f_NL for the equilateral model from both our primordial and late-time estimators which are consistent with each other, as well as with results already published in the literature. These general bispectrum estimation methods should prove useful for the analysis of nonGaussianity in the Planck satellite data, as well as in other contexts.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

General CMB and Primordial Bispectrum Estimation I: Mode Expansion, Map-Making and Measures of f_NL does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with General CMB and Primordial Bispectrum Estimation I: Mode Expansion, Map-Making and Measures of f_NL, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and General CMB and Primordial Bispectrum Estimation I: Mode Expansion, Map-Making and Measures of f_NL will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-103472

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.