In March 2025, the Atacama Cosmology Telescope (ACT) collaboration released its last cosmological analysis along with a new cosmic microwave background (CMB) dataset. The sixth data release (DR6), including data collected from 2017 to 2022, covers 40% of the sky at arcminute resolution providing precise maps of CMB temperature and polarization. In this talk, I will give an overview of the...
The Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) delivers some of the most precise small-scale measurements of the cosmic microwave background, requiring accurate treatment of astrophysical foregrounds at millimeter wavelengths. In this talk, we will present the DR6 parametric foreground model, which accounts for Galactic dust, extragalactic sources, and secondary CMB anisotropies....
I will present measurements of the temperature and E-mode polarization angular power spectra of the cosmic microwave background (CMB) from observations covering 4% of the sky with SPT-3G, the current camera on the South Pole Telescope. These maps are the deepest ever used in a CMB TT/TE/EE analysis. Both the maps and resulting power spectra have been rigorously validated through blind and...
In the second part of this talk, I will first briefly present the lensing bandpowers used in this analysis. These are lensing data inferred from the E-mode polarization maps using the Marginal Unbiased Score Estimator (MUSE), and they are the most precise to date at $L > 350$. Second, I will present constraints on $\Lambda$CDM and a few of its extensions with CMB data, highlighting the...
In the final part of this series of presentations, I will present cosmological implications from the cosmic microwave background (CMB) temperature and E-mode polarization power spectrum measurements previously introduced based on SPT-3G data. My presentation will cover the comparison and combination of the SPT data, as well as other contemporary CMB data sets, with state-of-the-art baryon...
The fifth (and final) data release of the Kilo-Degree Survey (KiDS) provides significantly more than just an increase in survey area. Instead, additional observations couple with improvements in data quality, data reduction, and value-added data-products, to make KiDS-DR5 the most robust and reliable release produced by KiDS to date. We leverage the lensing sample from this state-of-the-art...
We present a unified assessment of Bayesian model comparisons and cross-dataset tensions for the (still) standard $\Lambda$CDM model and some minimal extensions (curvature $\Omega_K$, sum of neutrino masses $\sum{m_\nu}$, dynamic dark energy $w$, or $w_0$ and $w_a$) in light of data from the cosmic microwave background (CMB), baryon acoustic oscillations (BAO), and supernovae (SN). Our...
We present a coherent cosmological analysis that combines data from the Planck satellite, the Atacama Cosmology Telescope (ACT), and the South Pole Telescope (SPT). We construct a unified likelihood that jointly fits temperature and polarization power spectra from all three datasets, implementing consistent modeling of Galactic and extragalactic foregrounds as well as instrumental systematics....
Measurements of spectral distortions of the CMB are one of the pillars on which we built our standard cosmological model. While measurements of CMB anisotropies have massively improved since their discovery, CMB spectral distortion were last measured by the COBE/FIRAS mission in the 1990s over the full sky. I will show how a re-analysis of archival data of COBE/FIRAS using modern foreground...
SMICA (Spectral Matching Independent Component Analysis) is a non-parametric method (Delabrouille et al. 2003; Cardoso et al. 2008) that operates in the spherical harmonic domain. It relies on the assumptions of statistical isotropy and Gaussianity of the signals. In this work, we relax the Gaussianity assumption to allow for weak non-Gaussianity, including three-point correlation functions of...
Claims have appeared in the literature of a statistically significant signal of parity violation in higher-order correlation functions from galaxy surveys. I will present some estimators of parity violation for the CMB bispectrum.
Context
Galaxy clusters in formation, or protoclusters, are important sites regarding the star formation history and the evolution of large scale structures, but only their galaxy members have been observed so far. The majority of their mass is expected to be under the form of non baryonic dark matter and intergalactic cold gas.
Aims
The Planck high redshift...
The second Planck catalogue of Sunyaev-Zeldovich sources (PSZ2) was originally presented by the Planck Collaboration as part of their 2015 data release. Along with the catalogue, a cosmological analysis was also published, conducted on the PSZ2 cosmological sample that contains 439 high signal-to-noise cluster candidates. However, this analysis was limited by the precision of its mass...
High-precision observations of the Cosmic Microwave Background (CMB) will yield improved measurements of the kinetic Sunyaev–Zel’dovich (kSZ) effect. In order to investigate the sensitivity of the kSZ signal to astrophysics, we build a neural-network emulator of the kSZ power spectrum, trained on the LoReLi II reionisation simulations, to enable fast inference of galaxy properties during...
Gravitational lensing of the Cosmic Microwave Background (CMB) is becoming one of our sharpest cosmological probes, with surveys such as SPT-3G and the Simons Observatory delivering deep polarization maps. In this talk, I will present a new optimal estimator for CMB lensing, which outperforms the widely used quadratic estimator in both accuracy and robustness. I will highlight recent advances...
The tightest constraints on the tensor-to-scalar ratio (BK18) are strongly limited by gravitational lensing, which can be reduced by high-resolution SPT-3G observations. SPT-3G and BICEP (SPO) have collected now enough data to achieve, in principle, 3 times better constraints on r than currently published (sigma(r) \sim 0.003 vs 0.009 now)), thanks to de-lensing. I'll discuss initial lensing...
Combining CMB and large-scale structure (LSS) data allows us to probe cosmic evolution from recombination to the present, constraining the amounts of baryonic and dark matter and testing general relativity on cosmological scales, as well as shedding light on the nature of dark energy.
In this talk, I present preliminary results from the clustering analysis of a magnitude-limited galaxy sample...
The Simons Observatory (SO) is already taking data and moving toward full science operations with its suite of small- and large-aperture telescopes. In this talk I will present recent updates on the project and outline its scientific potential, based on new forecasts.
The Simons Observatory (SO) is an ensemble of telescopes located in the Atacama Desert in Chile, targeting the detection of primordial B-modes in the polarization of the cosmic microwave background (CMB). The Small Aperture Telescopes (SATs) have been taking data for over a year and have already delivered their first CMB maps, which are currently under analysis. In this talk, we will present...
The last and only measurement of the CMB spectrum was performed by COBE-FIRAS in 1991, showing that it is close to a perfect blackbody emission. However, deviations referred to as CMB spectral distortions are expected. Due to its limited sensitivity, FIRAS could only give upper limits, leading to new space missions being proposed to perform this measurement. The balloon-borne mission BISOU...
I will present the current status of the LiteBIRD JAXA mission, after it entered in reformation period since September 2024, and recently went through a key review at JAXA in September 2025.
The proposal to build a high-frequency Small Aperture Telescope (SAT) as a new component of the Simons Observatory has gained increasing momentum over the recent years. This initiative, named KAIROS, is under evaluation for funding through the CNRS RI² program (“Recherche à risque et à impact”), with the backing of three CNRS institutes: IN2P3, INSU, and INP.
KAIROS aims to deploy a focal...
Panelists: N. Aghanim, J. Delabrouille, J. Errard, S. Galli, L. Montier
We investigate the impact of non-ideal half-wave plates (HWPs) on CMB polarization measurements in experiments such as the Simons Observatory and LiteBIRD. Because both foreground emission and instrumental effects vary with frequency, they are closely intertwined, and addressing one without the other can interfere with our estimation of cosmological parameters.
Through end-to-end...
Planck-HFI highly sensitive bolometers were considerably affected by cosmic-rays, producing spurious signals appearing as glitches in the raw astrophysical data. Since, the effect of cosmic rays on detectors is a major concern for future similar space missions. Their instruments will have a larger detection surface, an increased sensitivity, and much more stringent requirements on the...
Measuring r in low SNR, foreground-dominated observations of CMB B-modes is prone to biases that are hard to avoid and estimate when the exact properties of foreground emission are not known a priori. We use SMICA to forecast constraints on r for future ground-based observations and obtain unbiased constraints for various levels of foreground complexity.
The LiteBIRD satellite mission, an international collaboration led by the Japanese space agency (JAXA), aims to measure the CMB B-mode polarization with high precision, utilizing high-sensitivity instruments and large sky coverage to constrain the tensor-to-scalar ratio with unprecedented precision. The main difficulty in measuring this component lies first in its extremely small amplitude,...
Traditionally beams are treated in the harmonic space. However, it imposes several disadvantages like inability to treat non-spherical beams, always requiring an approximation. In the context of Simons Observatory experiment, we demonstrate a different approach based on treating the beams on a map-level. Accelerated by JAX and powered by FURAX software, it allows to circumvent the limitations...
Accurate statistical characterization of Galactic foregrounds is crucial for extracting cosmological information from CMB polarization data. However, the complexity of the interstellar medium leads to non-Gaussian structures that cannot be fully captured by traditional summary statistics, like the power spectrum. On the other hand, simulation and machine-learning approaches, while informative,...
