Abstract
We characterize the cosmic infrared background (CIB)-lensing bispectrum which is one of the contributions to the three-point functions of cosmic microwave background (CMB) maps in harmonic space. We show that the CIB-lensing bispectrum has a considerable strength and that it can be detected with high significance in the Planck high-frequency maps. We also present forecasts of the contamination on different shapes of the primordial non-Gaussianity fnl parameter produced by the CIB-lensing bispectrum and by the extragalactic point sources bispectrum in the Planck high-resolution CMB anisotropy maps. The local, equilateral and orthogonal shapes are considered for `raw’ single-frequency (i.e. without applying any component separation technique) and foreground-reduced Planck temperature maps. The CIB-lensing correlation seems to mainly affect orthogonal shapes of the bispectrum – with Δ f_nl^(ort) =-21 and -88 for the 143 and 217 GHz bands, respectively – while point sources mostly impact equilateral shapes, with Δ f_nl^(eq) =160, 54 and 60 at 100, 143 and 217 GHz. However, the results indicate that these contaminants do not induce any relevant bias on Planck fnl estimates when foreground-reduced maps are considered: using SEVEM for the component separation, we obtain Δ f_nl^(ort) =10.5 due to the CIB-lensing and Δ f_nl^(eq)=30.4 due to point sources, corresponding to 0.3σ and 0.45σ in terms of the Planck 2013 fnl uncertainty. The component separation technique is, in fact, able to partially clean the extragalactic source contamination and the bias is reduced for all the shapes. We have further developed single- and multiple-frequency estimators based on the Komatsu, Spergel & Wandelt formalism that can be implemented to efficiently detect this signal.
Author
Curto, A.; Tucci, M.; Kunz, M.; Martínez-González, E.
Journal
Monthly Notices of the Royal Astronomical Society
Paper Publication Date
July 2015
Paper Type
Astrostatistics