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Primordial non-Gaussianity: local curvature method and statistical significance of constraints on f_NL from WMAP data | | P. Cabella
; M. Liguori
; F.K. Hansen
; D. Marinucci
; S. Matarrese
; L. Moscardini
; N. Vittorio
; | | Date: |
1 Jun 2004 | | Journal: | Mon.Not.Roy.Astron.Soc. 358 (2005) 684-692 | | Subject: | astro-ph | | Abstract: | We test the consistency of estimates of the non-linear coupling constant f_{NL} using non-Gaussian CMB maps generated by the method described in (Liguori, Matarrese and Moscardini 2003). This procedure to obtain non-Gaussian maps differs significantly from the method used in previous works on estimation of f_{NL}. Nevertheless, using spherical wavelets, we find results in very good agreement with (Mukherjee and Wang 2004), showing that the two ways of generating primordial non-Gaussian maps give equivalent results. Moreover, we introduce a new method for estimating the non-linear coupling constant from CMB observations by using the local curvature of the temperature fluctuation field. We present both Bayesian credible regions (assuming a flat prior) and proper (frequentist) confidence intervals on f_{NL}, and discuss the relation between the two approaches. The Bayesian approach tends to yield lower error bars than the frequentist approach, suggesting that a careful analysis of the different interpretations is needed. Using this method, we estimate f_{NL}=-10^{+270}_{-260} at the 2sigma level (Bayesian) and f_{NL}=-10^{+310}_{-270} (frequentist). Moreover, we find that the wavelet and the local curvature approaches, which provide similar error bars, yield approximately uncorrelated estimates of f_{NL} and therefore, as advocated in (Cabella et al. 2004), the estimates may be combined to reduce the error bars. In this way, we obtain f_{NL}=-5pm 85 and f_{NL}=-5pm 175 at the 1sigma and 2sigma level respectively using the frequentist approach. | | Source: | arXiv, astro-ph/0406026 | | Services: | Forum | Review | PDF | Favorites | |
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