Colloque national CMB-France #4

22 nov. 2022, 09:30 → 23 nov. 2022, 17:40 Europe/Paris

Amphi Durand (Sorbonne Université (Campus Jussieu))

L'initiative CMB-France vise à mettre en place une animation scientifique au niveau national autour des études CMB (cmb-france.cnrs.fr).

Le CMB-France #4 aura lieu les 22 et 23 Novembre 2022 à l'Université Paris-Sorbonne

(Amphi Durand, Campus Jussieu).

 

L'inscription est gratuite mais obligatoire: ici.

 

CMB-France peut prendre en charge les missions (dans la limite des stocks disponibles). Renseignez-vous auprès de M. Tristram.

 

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 (avant le 7 Novembre).

 

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

 

 Cette action est soutenue par le PNCG.

mar. 22 novembre

13:00 → 13:30 Introduction

13:30 → 17:40 Session #1

13:30 Status of the next ACT release (DR6)

Some status of the forthcoming ACT release (DR6)

Orateur: Blake Sherwin

Sherwin_ACT_CMBFranceTalk.pdf

14:10 High-resolution SZ observations for cluster cosmology with NIKA2

As the largest gravitationally bound objects in the Universe, galaxy clusters are key tools to study large-scale structure formation processes and to constrain cosmological models. These studies, however, require the mass of clusters to be calibrated, for example with a mass-observable scaling relation. Systematic effects, in particular at high redshift, have an impact on this calibration and are currently the main limitation of cluster-based cosmology.

NIKA2, a millimeter camera installed at the IRAM 30-m telescope is a key experiment to extend our understanding of galaxy clusters. Combining sub-arcminute (17.2’’ at 150 GHz) angular resolution and a 6.5 arcmin diameter field of view, NIKA2 is resolving the Sunyaev-Zel'dovich (SZ) effect towards clusters up to high redshifts. Combined with X-ray data from XMM-Newton satellite, we can infer with high precision the thermodynamical properties and the hydrostatic masses of such objects within the NIKA2 SZ Large Program (LPSZ), which covers a representative sample of 45 galaxy clusters at redshifts from 0.5 to 0.9.

In this talk I will present the latest results of the LPSZ and I will show for the first time preliminary results on the LPSZ sample characteristics, including the cluster masses and mean pressure profile. Based on these results, I will discuss the systematic effects impacting the mass reconstruction, such as the presence of sub-structures, and their implication for cluster cosmology.

Orateur: Corentin Hanser (UGA)

CMBFrance_HanserCorentin.pdf

14:50 SZ science with next generation CMB maps

With high resolution and low noise multifrequency CMB maps, combined with upcoming data from galaxy surveys, observables based on the Sunyaev Zeldovich (SZ) effect constitute a promising avenue for constraining cosmological models and reshaping our understanding of galaxy formation. In this talk we will review what the thermal and kinetic SZ effects are, why they are going to become a cornerstone of precision cosmology, and how we may use them to maximize the science output of next generation surveys.

Orateur: M. Boris Bolliet (Cambridge University, DAMTP)

15:30 Café

16:00 CMB-S4 Update

After a general overview of CMB-S4 and an update, it will include an overview of the Analysis of Alternatives.

Orateur: M. John Carlstrom

Carlstrom_CMB-S4_Update_221122.pdf

mer. 23 novembre

09:00 → 09:30 Café

09:30 → 12:30 Session #2

09:30 Updates from the South Pole Telescope

I will report the current status of the SPT-3G observations and highlight prospects for the near future.

Orateur: Silvia Galli (IAP)

2022 11 CMB France(2).pdf

10:10 LiteBIRD status

Status of the LiteBIRD mission

Orateur: Ludovic Montier (IRAP)

LiteBIRD_Status_CMB-France_Nov22.pdf

10:50 Café

11:10 Constraining cosmology with the summer fields of the South Pole Telescope

The South Pole Telescope (SPT) is observing the CMB with arcminutes resolution, with its third generation camera (SPT-3G). One of the main goals is to improve the current constraints on cosmological parameters. During the first observing season, SPT-3G observed its baseline sky patch (1500 deg2), and obtained cosmological constraints consistent with those from the Planck mission. Deeper observations of the SPT-3G baseline field are currently ongoing, as well as observations of additional 3000 deg2 that are observed during the summer season (the “summer fields"). In this talk I will present the ongoing analysis of the SPT-3G summer fields, and forecasts of the cosmological parameters relying on the SPT-3G extended survey (baseline+summer fields). The inclusion of the SPT-3G summer fields in the combined analysis of the SPT-3G baseline field and Planck data is expected to improve the constraints by 20% for the ΛCDM model, and by up to 50% for ΛCDM extensions.

Orateur: Federica Guidi (IAP)

guidi_cmbfrance4.pdf

11:50 Building the SPT-3G 19/20 likelihood

The South Pole Telescope (SPT) observes the CMB anisotropies with arcminute resolution using its state-of-the-art camera (SPT-3G). Constraints on cosmological parameters from the obtained data will be as tight as Planck’s one while remaining independent from the satellite experiment, thus allowing us to test the consistency of the two data sets and investigate new physics. Reliable cosmological parameters necessitate an accurate covariance matrix. In recent work, we introduced a framework for computing accurate analytical covariance matrices for small survey areas. In this talk, I will present how we adapted this framework to the specific case of SPT-3G. First, we mitigate the point source contamination with Gaussian-constrained signal realization, assert the robustness of this method, and propagate the impact on the final covariance matrix. Then, we consider the impact of data anisotropies and propose an adequate renormalization of the covariance matrix.

Orateur: Etienne Camphuis (Institut d'Astrophysique de Paris)

20221123_cmbfrance.pdf

13:30 → 14:00 Café

14:00 → 17:40 Session #3

14:00 UK contribution to SO

Presentation of the UK contribution to SO

Orateur: Dr Michael Brown (Manchester University)

SO_UK_Paris_Nov_2022.pdf

14:40 Retrieving EoR constraints from small-scale CMB data with an improved kSZ model

In this talk, I will present the first constraints on the reionisation timeline obtained from a consistent analysis of small- and large-scale CMB data, namely SPT and Planck. Utilising random forests trained to reconstruct the kinetic and thermal Sunyaev Zel’dovich angular power spectra from a set of cosmological and reionisation parameters, according to the Salvati+2018 and Gorce+2020 frameworks, we are able to retrieve the cosmological information enclosed in these foregrounds and obtain a direct measurement of the reionisation mid- and end-points. By breaking degeneracies between foreground amplitudes, this approach enables a 5 sigma measurement of the kSZ amplitude, with error bars cut in half compared to previous analyses. We also present the first direct measurement of the amplitude and shape of the patchy kSZ signal stemming from redshifts higher than 5.

Orateur: Marian Douspis (IAS)

Douspis_EoR_CMB_FR_4.pdf

15:20 Café

15:40 Galaxy clusters in the mm wavelengths: combine Planck and SPT

Galaxy clusters are a powerful cosmological probe, being able to describe the latest evolution of large scale structure.
In recent years, cluster catalogs of thousands of objects have been detected in the mm wavelengths, through the thermal Sunyaev-Zeldovich effect. CMB experiments have therefore a fundamental role also in providing observables for the recent evolution of the Universe.
The cluster mass calibration provides the largest source of uncertainties in current cluster cosmology. Indeed, since we can not measure directly cluster masses, the cosmological analysis relies on scaling relations between the survey observable (proportional to the Compton parameter, for clusters detected with tSZ effect) and the cluster mass. I will review the state of the art for tSZ cluster cosmology, focusing in particular on a novel analysis of Planck data.
I will also show results for the first combined analysis of Planck and SPT cluster catalogs. In this first analysis, we provide a mass calibration for Planck clusters completely independent on theoretical assumptions, simply using the constraining power of SPT clusters.
We show therefore the huge potentiality of combining catalogs from different experiments, in improving the cosmological analysis and the treatment of different systematic uncertainties.

Orateur: Laura Salvati (IAS, Paris Saclay)

Salvati.pdf

16:20 Frequency dependence of the thermal dust E/B ratio and EB correlation: insights from the spin-moment expansion

The change of physical conditions across the turbulent and magnetized interstellar medium (ISM) induces a 3D spatial variation of the properties of Galactic polarized emission. The observed signal results from the averaging of different spectral energy distributions (SED) and polarization angles, along and between lines of sight. As a consequence, the total Stokes parameters Q and U will have different distorted SEDs, so that the polarization angle becomes frequency dependent. In the present work, we show how this phenomenon similarly induces a different distorted SED for the three polarized angular power spectra EE, BB and EB, implying a variation of the EE/BB ratio with frequency. We demonstrate how the previously introduced spin-moment formalism provides a natural framework to grasp these effects, allowing us to derive analytical predictions for the spectral behaviors of the polarized spectra, focusing here on the example of thermal dust polarized emission. After a quantitative discussion based on a model combining emission from a filament with its background, we further reveal that the spectral complexity implemented in the dust models commonly used by the cosmic microwave background (CMB) community produce such effects. This new understanding is crucial for CMB component separation, in which an extreme accuracy is required in the modeling of the dust signal to allow for the search of the primordial imprints of inflation or cosmic birefringence. For the latter, as long as the dust EB signal is not measured accurately, great caution is required about the assumptions made to model its spectral behavior, as it may not simply follow from the other dust angular power spectra.

Orateur: Léo Vacher (Institut de recherche en astrophysique et planétologie (IRAP))

EE-BB_cmbfrance.pdf