Closed universes and the CMB / SpinSILC: CMB polarisation component separation for nextgeneration experiments
APA
Bonga, B. & Rogers, K. (2016). Closed universes and the CMB / SpinSILC: CMB polarisation component separation for nextgeneration experiments. Perimeter Institute. https://pirsa.org/16080032
MLA
Bonga, Beatrice, and Keir Rogers. Closed universes and the CMB / SpinSILC: CMB polarisation component separation for nextgeneration experiments. Perimeter Institute, Aug. 04, 2016, https://pirsa.org/16080032
BibTex
@misc{ pirsa_PIRSA:16080032, doi = {10.48660/16080032}, url = {https://pirsa.org/16080032}, author = {Bonga, Beatrice and Rogers, Keir}, keywords = {Cosmology}, language = {en}, title = {Closed universes and the CMB / SpinSILC: CMB polarisation component separation for nextgeneration experiments}, publisher = {Perimeter Institute}, year = {2016}, month = {aug}, note = {PIRSA:16080032 see, \url{https://pirsa.org}} }

Radboud Universiteit Nijmegen

University College London
1. Beatrice Bonga, "Closed universes and the CMB",
Abstract:
Cosmic microwave background (CMB) observations put strong constraints on the spatial curvature via estimation of the parameter $\Omega_k$. This is done assuming a nearly scaleinvariant primordial power spectrum. However, we found that the inflationary dynamics is modified due to the presence of spatial curvature leading to corrections to the primordial power spectrum. When evolved to the surface of last scattering, the resulting temperature anisotropy spectrum shows deficit of power at low multipoles ($\ell<20$). This may partially explain the observed $3 \sigma$ anomaly of power suppression for $\ell <30$. Since the curvature effects are limited to low multipoles, the estimation of cosmological parameters remains robust under inclusion of positive spatial curvature.
(This talk is based on http://arxiv.org/abs/1605.07556)
2. Keir Rogers, "SpinSILC: CMB polarisation component separation for nextgeneration experiments",
Abstract:
Bmode polarisation is a powerful cosmological observable which in principle allows the detection of a stochastic background of gravitational waves predicted by inflation, and gives strong constraints on the neutrino sector using the weak gravitational lensing of the cosmic microwave background (CMB). Astrophysical foregrounds present a formidable obstacle in extracting these signatures of new physics from CMB polarisation data. Indeed, recent forecasts for post2020 CMB experiments predict one sigma constraints on, for example, the tensortoscalar ratio of about 10^4 and the sum of neutrino masses of about 30 meV. However, these constraints are predicated on highlyaccurate foreground and noise removal. I will present the first component separation method specifically developed for this task and tested on the latestrelease Planck data. The method, SpinSILC, is an internal linear combination algorithm that uses spin wavelets to fully analyse the spin polarisation signal P = Q + iU, where Q and U are the measured Stokes parameters. This allows all the information in the measured signal to be used in extracting the cosmological background. Furthermore, SpinSILC is the first method to simultaneously and efficiently perform component separation and the EB decomposition necessary for cosmological analyses thanks to the construction of the spin wavelets we use. SpinSILC also uses the morphological information of the foregrounds and CMB to better localise the cleaning algorithm. This is because the wavelets we use are additionally directional, and, when convolved with signals on the sphere, can separate the filamentary structures which are characteristic of both the CMB and foregrounds. I will present the results of applying these novelties to Planck data and discuss further how SpinSILC can also mitigate the EB leakage problem of future CMB experiments.