Journal Article

Adiabatic versus isocurvature non-Gaussianity

Chiaki Hikage, Dipak Munshi, Alan Heavens and Peter Coles

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 404, issue 3, pages 1505-1511
Published in print May 2010 | ISSN: 0035-8711
Published online May 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.16362.x
Adiabatic versus isocurvature non-Gaussianity

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We study the extent to which one can distinguish primordial non-Gaussianity (NG) arising from adiabatic and isocurvature perturbations. We make a joint analysis of different NG models based on various inflationary scenarios: local-type and equilateral-type NG from adiabatic perturbations and local-type and quadratic-type NG from isocurvature perturbations together with a foreground contamination by point sources. We separate the Fisher information of the bispectrum of cosmic microwave background temperature and polarization maps by l for the skew spectrum estimator introduced by Munshi and Heavens to study the scale dependence of the signal-to-noise ratio of different NG components and their correlations. We find that the adiabatic and the isocurvature modes are strongly correlated, though the phase difference of acoustic oscillations helps to distinguish them. The correlation between local- and equilateral-type is weak, but the two isocurvature modes are too strongly correlated to be discriminated. Point source contamination, to the extent to which it can be regarded as white noise, can be almost completely separated from the primordial components for l > 100. Including correlations among the different components, we find that the errors of the NG parameters increase by 20–30 per cent for the Wilkinson Microwave Anisotropy Probe 5-year observation, but ≃5 per cent for Planck observations.

Keywords: methods: analytical; methods: statistical; cosmic microwave background; early Universe

Journal Article.  3336 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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