Colloque national CMB-France #1

2 juin 2021, 13:55 → 3 juin 2021, 19:00 Europe/Paris

Cette initiative vise à mettre en place une animation scientifique au niveau national autour des études CMB.

 

La première action associée que nous souhaitons mettre en place est l’organisation d’un colloque national CMB avant l’été.

 

Nous proposons ce premier colloque sous la forme de 2 demi-journées le 2 et 3 juin 2021, en distanciel.

L’agenda est en cours de finalisation mais l’idée de ces colloques est de:

• présenter les nouveautés scientifiques et les nouveaux résultats dans le domaine
• donner un statut sur l’avancement des expériences ou des projets en cours
• permettre aux jeunes (post-doc, PhD) de présenter leur travail

N’hésitez pas à nous contacter ou à soumettre vos propositions de presentation

 

Les informations de connexion seront envoyées par la mailing-liste cmb-france. Pensez à vous inscrire.

 

  Cette action est soutenue par le PNCG.

mercredi 2 juin

14:00 → 14:10 Welcome CMB-France

14:10 → 14:40 CMB results: #1

14:15 SPT3G Results

Orateur: Silvia Galli (IAP)

galli_spt3g_results.mp4

14:40 → 14:50 break

14:50 → 15:50 Open session: #1

14:50 Impact of polarised extragalactic sources on the measurement of CMB B-mode anisotropies

Using state-of-the-art models of galaxy evolution for both radio and dusty galaxies and polarisation fractions as recently measured, we computed the B-mode power spectra of the three extragalactic foregrounds: radio source shot noise, dusty galaxy shot noise, and clustering. We will discuss their relative levels for different CMB experiments and will compare their amplitudes to that of the instrument noise and of the primordial B-mode signal.

Orateur: Guilaine Lagache (LAM)

lagache_polarized_extragalactic_sources.mp4

15:10 Phase harmonics statistics and denoising/components separation

Phase harmonics statistics are recently developed non-Gaussian statistics, inspired by convolutional neural networks, which characterize the interaction between scales in a given process. It is possible to build from these statistics a realistic generative model of a process from a very limited number of samples. In this talk, I will show how this possibility has allowed the development of new methods for denoising and components separation of different fields related to CMB experiments.

Orateur: Erwan Allys (LPENS, Paris)

Allys_phase_harmonics_statistics.mp4

15:30 Phase-harmonic generative models for likelihood-free polarization foreground marginalization

I will present single frequency morphological foreground removal and denoising using deep learning (in a Bayesian likelihood-free framework) using phase harmonic augmentation. With only a single training image of polarized dust foregrounds, we are able to generate new realisations using wavelet phase harmonic synthesis. In a likelihood-free inference framework, these new realisations can be used for Bayesian foreground map-cleaning (using high dimensional Moment Networks) and cosmological parameter inference.

Orateur: Dr Niall Jeffrey (École normale supérieure)

Jeffey_likelihood-free_foreground_marginalization.mp4

15:50 → 16:00 break

16:00 → 17:00 CMB experiments: #1

Président de session: Guilaine Lagache (LAM)

16:00 Concerto

Status of Concerto

Orateur: Andrea Catalano (LPSC - Grenoble)

catalano_concerto.mp4

16:20 QUBIC

Statut QUBIC

Orateur: Jean-Christophe Hamilton (APC)

hamilton_qubic.mp4

News from QUBIC

16:40 Ali-CPT

Statut Ali-CPT

Orateur: Jacques Delabrouille (APC)

delabrouille_alicpt.mp4

jeudi 3 juin

14:00 → 14:50 CMB results: #2

Président de session: Nabila Aghanim

14:00 SPIDER

Talk on the last SPIDER results by the SPIDER collaboration:
"A Constraint on Primordial B-Modes from the First Flight of the SPIDER Balloon-Borne Telescope",
https://arxiv.org/abs/2103.13334

Orateur: Riccardo Gualtieri (Argonne)

gualtieri_spider.mp4

SPIDER_first_flight_results_and_beyond.pdf

14:30 Planck constraints on the tensor-to-scalar ratio

Je présenterais les contraintes sur le rapport tenseur-sur-scalaire obtenue a partir de Planck ("Planck constraints on the tensor-to-scalar ratio" https://arxiv.org/abs/2010.01139).

Orateur: Matthieu Tristram (IJClab, CNRS, France)

Planck constraints on the tensor to scalar ratio.pdf

tristram_planck_constraints_tensor_to_scalar_ratio.mp4

14:50 → 15:00 break

15:00 → 16:00 CMB experiments: #2

Président de session: Nabila Aghanim

15:00 LiteBIRD

Status LiteBIRD

Orateur: Ludovic Montier (IRAP)

montier_litebird.mp4

15:20 Simons Observatory

Statut de SO

Orateur: Hamza El Bouhargani (AstroParticle and Cosmology laboratory (APC))

ElBouhargani_simons_observatory.mp4

15:40 CMB-S4

Statut CMB-S4

Orateur: François R. Bouchet (IAP)

bouchet_cmbs4.mp4

16:00 → 16:10 break

16:10 → 17:50 Open session: #2

16:10 Cosmology with the T-E correlation coefficient

Precise measurements of cosmological parameters have revealed tensions in the standard model of cosmology. One way of studying these tensions is to check the robustness of our datasets using observables that are less sensitive to systematic effects. In this talk I will discuss the properties of the Pearson's correlation coefficient of T and E modes $\mathcal{R}_\ell^{TE}$; a combination of the power spectra which is insensitive to multiplicative instrumental systematics. I will present the first cosmological constraints from the correlation coefficient using the latest Planck data release (PR4).

Orateur: Adrien La Posta (IJCLab, CNRS, France)

laposta_Rl_TE_correlation.mp4

16:30 Moment expansion: a new path towards capturing the CMB B-modes with LiteBIRD

In the quest for the Cosmic Microwave Background (CMB) primordial $B$-modes, being able to accurately characterise the polarised foregrounds will be decisive. The mismodeling of their complex spectral properties could lead to a bias on the final estimation of the tensor-to-scalar ratio $r$. Finding a method to avoid this issue is central for future key surveys like the LiteBIRD satellite, which aims at constraining the faint primordial signal leftover by Inflation with an accuracy allowing to constrain $r$ down to $1 \times 10^{-3}$. Part of the problem lies in the knowledge of spatial variations of the spectral properties of the astrophysical sources over the sky (in the instrumental beam and through harmonic expansion) and along the line of sight. Such variations lead to unavoidable distortions of the spectral energy distribution (SED) that can not be easily anticipated by standard component separation methods.This issue may be tackled using a moment expansion of the foreground SEDs. As proposed by Chluba et al (2017) ,this innovative parametrisation method imposes no a priory assumptions on the sky complexity.
In this paper, we apply this formalism in spherical harmonic space to LiteBIRD simulated data, considering only the dominant polarised foreground source at high frequency : thermal dust emission. Different scenarios of increasing complexity are considered. In the most realistic case, pushing the expansion around the canonical modified black body allows us to remove biases on $r$, while insuring an error budget compatible with LiteBIRD requirements. The direction just opened by moment expansion is promising to face the challenges set by LiteBIRD, and more generally, next generation CMB experiments. However, we note the existence of degeneracies between $r$ and the parameters of the moment expansion, that may compromise a simple analysis in the presence of complex dust SED. The existence of correlations between the dust complexity and the tensor-to-scalar ratio could be problematic for component separation methods even beyond the moment expansion.

Orateur: Léo Vacher ({UNIV TOULOUSE PAUL SABATIER}UMR5277)

vacher_moment_expansion.mp4

16:50 NIKA2

Analyses NIKA2

Orateur: Juan Francisco Macias-Perez (LPSC)

maciasperez_nika2.mp4

17:10 Better accounting for reionisation in CMB data analysis: the KSZ effect

CMB data is a crucial source of information about reionisation. Despite the exquisite measurements of Planck on large scales and SPT, ACT or future CMB-S4 experiments on small scales, the way CMB data is currently used to constrain reionisation is coarse.
In this talk, we focus on the kinetic Sunyaev-Zel’dovich effect in the context of patchy reionisation and introduce a new way to relate both the shape and amplitude of its angular power spectrum to reionisation global history and morphology. Until now, only rough scalings of the kSZ amplitude with reionisation duration or midpoint were used. Our approach is based on a novel and extremely simple description of the power spectrum of the free electrons density contrast, however sufficient to describe the physics at stake, as confirmed when applying it to a wide range of simulations. Combined with 21cm intensity mapping, this innovative tool will allow a much more optimal use of future CMB observations to constrain the physics of reionisation.
After introducing this new formalism, I will present the first results obtained when including it in Planck and SPT data analysis and the insights on reionisation that can be deduced from them.

Orateur: Adélie Gorce (Institut d'Astrophysique Spatiale)

gorce_reionization_ksz_effect.mp4

17:30 Detection of the kinetic Sunyaev-Zel'dovich effect in galaxy clusters with Planck data

The kinetic Sunyaev-Zel'dovich (kSZ) effect is caused by the scattering of CMB photons off the electrons due to the object's bulk motion. It is proportional to the peculiar velocity but also depends on the properties of the virialized gas as well as the gas surrounding halos.

I will present the statistical detection of the kSZ effect from ~30,000 galaxy clusters identified in the SDSS survey at ~3.5 sigma using the Planck data. This measurement exhibited ionized gas beyond the virial radius of the galaxy clusters with average masses of M500~10^14 Msun. The derived gas fraction of the galaxy clusters was found to be fgas=0.12+-0.04, still consistent with the cosmic baryon fraction.

Orateur: Hideki Tanimura (Institut d'Astrophysique Spatiale)

tanimura_detecting_kSZ_in_planck.mp4