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Adrien LA POSTA (Oxford University)13/10/2025 14:00
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...
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Dr Benjamin Beringue (APC, CNRS)13/10/2025 14:20
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....
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Etienne Camphuis (Institut d'Astrophysique de Paris)13/10/2025 14:40
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...
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Ali Rida Khalife (IAP-CNRS and Sorbonne University)13/10/2025 15:00
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...
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Lennart Balkenhol (Institut d'Astrophysique de Paris)13/10/2025 15:20
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...
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Alexandre Huchet (APC)13/10/2025 15:40
QUBIC, the Q-U Bolometric Interferometer for Cosmology, is a telescope that observes the polarisation of the sky in the millimetre-wavelength range. Its goal is to detect the primordial B-modes of polarisation in the CMB by combining the sensitivity of bolometers with the good understanding of interferometry systematics. This dual aspect of QUBIC allows it to perform spectral imaging, that is,...
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Angus Wright (Ruhr University Bochum)13/10/2025 16:30
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...
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Etienne Burtin (IRFU/CEA - Université Paris-Saclay)13/10/2025 16:50
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Dr Lukas Hergt (IJCLab, IN2P3, CNRS)13/10/2025 17:10
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...
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Matthieu Tristram (IJCLab, CNRS)13/10/2025 17:30
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....
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Giulio Fabbian (Institut d'Astrophysique Spatiale (IAS))13/10/2025 17:50
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...
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Michele Citran (APC, IJCLab)13/10/2025 18:10
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...
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Dr Martin Bucher (APC)13/10/2025 18:30
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.
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Tanguy DUSSERRE (Institut d'Astrophysique Spatiale)14/10/2025 09:00
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
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The Planck high redshift... -
Gaspard Aymerich (Institut d'Astrophysique Spatiale, Université Paris-Saclay)14/10/2025 09:20
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...
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Dr Lisa Mc Bride (Institut d'Astrophysique Spatiale)14/10/2025 09:40
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...
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Ola Kusiak (Cambridge)14/10/2025 10:00
In this talk, I will present the projected-fields kSZ estimator, where the kSZ signal is squared before cross-correlating it with a LSS field to avoid the cancellation of the signal due to electron velocity, which is equally likely to be positive or negative. Crucially, this estimator does not require spectroscopic redshift information.
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I will discuss new developments on the projected-fields... -
ll783 Legrand (DAMTP, University of Cambridge)14/10/2025 10:50
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...
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Julien Carron (University of Geneva)14/10/2025 11:10
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...
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Dr Margherita Lembo (Institut d'Astrophysique de Paris (IAP))14/10/2025 11:30
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.
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In this talk, I present preliminary results from the clustering analysis of a magnitude-limited galaxy sample... -
M. Thibaut Louis (LAL)14/10/2025 11:50
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.
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Amalia Villarrubia Aguilar (APC), Pierre Masson (APC)14/10/2025 12:10
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...
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Nabila Aghanim14/10/2025 14:00
Both standard and non-standard physics processes inevitably lead to distortions of the CMB black-body shape. They provide a unique opportunity to reveal a novel tracer of the early Universe, particle physics and structure formation. The presentation will cover some of the ongoing efforts in BISOU (Cnes Balloon project) and FOSSIL (ESA M8 proposal) to design and fly a future satellite aimed at...
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Morgane LOQUET LE GALL (IAS)14/10/2025 14:20
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...
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Xavier COULON (IAS)14/10/2025 14:40
In the 1990s, the COBE/FIRAS mission measured the Cosmic Microwave Background (CMB) spectrum and demonstrated that its spectral energy distribution is extremely close to a perfect blackbody. However, theory shows that tiny departures from a black body are expected at the level of $\Delta I/I \simeq 10^{-5}$, known as spectral distortions. The two main types of CMB spectral distortions are the...
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Ludovic Montier (IRAP)14/10/2025 15:00
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.
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Julien Tang (LBNL/CPB)14/10/2025 15:20
Unambiguously detecting the primordial gravitational waves signal requires precise subtraction of confounding foregrounds, which have much larger amplitude. One such foreground is B-modes generated by gravitational lensing of E-modes.
We validated an optimal map-based delensing pipeline on simulations, with different complexities of noise including white and 1/f noise, homogeneous and...
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Elisa Russier14/10/2025 15:40
The Probe of Inflation and Cosmic Origins (PICO) is a space mission submitted to the Astro2020 Decadal Review as an inflation probe. In a previous paper (Aurlien et al, 2023), the PICO team demonstrated performance based on simplifying assumptions, in particular, white homogeneous noise. We present updated r forecasts, based on end-to-end simulations, for a realistic noise including...
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Clara Vergès (LBNL)14/10/2025 16:30
The South Pole Observatory (SPO) brings together the BICEP and SPT collaborations with the goal of providing state-of-the-art constraints on inflationary gravitational waves. The BICEP program has a long history of setting constraints on the tensor-to-scalar ratio r, including the current leading constraint $\sigma(r) = 0.009$ (PRL, 2021). Future results will benefit from the increased...
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Dr Josquin Errard (APC / CNRS)14/10/2025 16:50
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...
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14/10/2025 17:10
Panelists: N. Aghanim, J. Delabrouille, J. Errard, S. Galli, L. Montier
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Ema TSANG KING SANG (APC-CNRS)15/10/2025 09:00
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...
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Anaïs Besnard (Institut d'Astrophysique Spatiale (IAS))15/10/2025 09:20
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...
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Mathias Regnier (IRAP)15/10/2025 09:40
We present the development of a local bubble model designed to characterize polarized Galactic foregrounds emission at high Galactic latitudes. The framework focuses on modeling the polarized dust emission (Stokes Q and U) as well as the synchrotron contribution, under the hypothesis of a magnetized local cavity surrounding the Solar neighborhood. By combining observational constraints with...
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Jacques Delabrouille (IN2P3)15/10/2025 10:00
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.
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Hoang Viet Tran (APC, Université Paris Cité)15/10/2025 10:20
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,...
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Pierre CHANIAL (APC)15/10/2025 11:00
We present Furax, a Python library for solving inverse problems in astrophysical and cosmological data analysis, with focus on CMB observations.
Why JAX? JAX provides JIT compilation, automatic differentiation, and seamless GPU/TPU parallelization essential for large-scale matrix operations in CMB analysis. Its functional programming paradigm enables efficient, composable linear...
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Wuhyun Sohn (APC / CNRS)15/10/2025 11:20
I will present three applications of FURAX, a JAX-powered, open-source framework designed for modular and efficient CMB data analysis. First, I will discuss mapmaking—the conversion of time-ordered data into sky maps—with an emphasis on strategies to mitigate systematic effects. Second, I will show how FURAX enables robust component separation in the map domain, extracting CMB signals from sky...
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Artem BASYROV (APC, CNRS)15/10/2025 11:40
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...
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Simon Biquard (APC / CNRS)15/10/2025 12:00
Based on https://arxiv.org/abs/2509.16302
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Dr Alexandros Tsouros (LPENS Paris)15/10/2025 12:20
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,...
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Sébastien Pierre (LPENS)15/10/2025 12:40
Extracting a signal of interest (LSS, CMB, Galactic emission…) from contaminated observations is a central challenge in many astrophysical and cosmological analysis. However, instrumental systematics, Galactic foregrounds or other contaminants usually makes the forward process stochastic and non-invertible, leaving the inverse problem ill-posed. A probabilistic framework is therefore required...
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Marian Douspis (IAS)
Planck has been producing the first tSZ power spectrum estimate from "all-sky" y-map in 2013. New estimates has been produced from updates of the ymap in parallele to estimation derived from the CMB data analyses by Planck, ACT and SPT. The latter just released there last results in the last month. I will review the different (sometimes in tension) signal estimates (and analyses they are...
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