Impact of polarization on the intrinsic cosmic microwave background bispectrum

Abstract

(2014) Impact of polarization on the intrinsic cosmic microwave background bispectrum. Physical Review D, 90 (10). ISSN 1550-7998 This version is available from Sussex Research Online: http://sro.sussex.ac.uk/57291/ This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the URL above for details on accessing the published version. Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way.Impact of polarization on the intrinsic cosmic microwave background bispectrum We compute the cosmic microwave background (CMB) bispectrum induced by the evolution of the primordial density perturbations, including for the first time both temperature and polarization using a second-order Boltzmann code. We show that including polarization can increase the signal-to-noise by a factor 4 with respect to temperature alone. We find the expected signal-to-noise for this intrinsic bispectrum of S=N ¼ 3.8; 2.9; 1.6 and 0.5 for an ideal experiment with an angular resolution of l max ¼ 3000, the proposed CMB surveys PRISM and COrE, and Planck's polarized data, respectively; the bulk of this signal comes from E-mode polarization and from squeezed configurations. We discuss how CMB lensing is expected to reduce these estimates as it suppresses the bispectrum for squeezed configurations and contributes to the noise in the estimator. We find that the presence of the intrinsic bispectrum will bias a measurement of primordial non-Gaussianity of local type by f intr NL ¼ 0.66 for an ideal experiment with l max ¼ 3000. Finally, we verify the robustness of our results by recovering the analytic approximation for the squeezed-limit bispectrum in the general polarized case.

The intrinsic bispectrum of the cosmic microwave background

“…It is our intention to make the bispectrum and Fisher parts of SONG public later in 2013 [66] as independent modules for CLASS [43,44]. We shall release the full code once the extensions discussed above have been completed.…”

Weak lensing induced by second-order vector mode

“…These modes do not have free parameters, since the first-order scalar mode is well determined by current observations. The secondary CMB polarization anisotropy induced by these modes has been discussed in the literature [24][25][26][27][28]. The application of these modes to the weak lensing is also possible and quite interesting.…”

CMBB-mode non-Gaussianity

“…Our analysis does not include possible contributions to the observed BT T bispectrum from lensing, foregrounds, or systematic effects. We also neglect late-time effects, analagous to those that are known to produce T T T correlations at the level of f NL ∼ 1 even for purely Gaussian initial conditions [48,49,57,58]. We leave the computation of these contributions to future work.…”