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Alain Blanchard05/11/2025 14:00
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Aymeric Galan (MPA, TUM)05/11/2025 14:10
Time-delay cosmography with lensed quasars is a one-step method for estimating the Hubble constant in the local Universe independently of the cosmic distance ladder. It does not require any intermediate calibration and relies on measuring the time delays between multiple images of strongly lensed quasars, which are inversely proportional to the Hubble constant.
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In this talk, I will present... -
Rafael Kebadian (CPPM)05/11/2025 14:50
$f\sigma_8$ is a powerful probe at low redshift to discriminate between different theories of gravity. In linear theory, this parameter is directly related to the velocity field. In this talk, I will show how the peculiar velocities of ZTF Type Ia supernovae can be used to measure $f\sigma_8$. I apply a maximum likelihood approach together with realistic simulations based on N-body mocks. I...
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Isaac Tutusaus (ICE/IRAP)05/11/2025 15:10
After a successful launch in 2023, and the beginning of the scientific survey last year, Euclid has become the first stage IV photometric survey in operations. In addition to all the cosmological probes that can be considered from Euclid's photometric observations, a spectroscopic survey is also being performed, allowing us to add even more probes to a combined analysis from Euclid data alone....
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Pauline Zarrouk (LPNHE)05/11/2025 15:50
To unlock the full potential of upcoming datasets and probe the dark sector, we must move beyond information-compression techniques towards field-level analysis. The Aquila Consortium has been at the forefront of developing Bayesian field-level inference (FLI) with the BORG algorithm.
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In this talk, I will briefly remind the basics of FLI with BORG, then I will present its application to ZTF... -
Thibaut Louis (LAL)05/11/2025 16:40
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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Thomas Montandon (Laboratoire Univers et Particule de Montpellier (LUPM))05/11/2025 17:20
Upcoming surveys of cosmic structures will probe scales ranging from the nonlinear regime to scales close to the cosmological horizon. This opens the door to testing the ΛCDM model, as well as early universe scenarios with primordial non-Gaussianity. Modeling the galaxy angular bispectrum is particularly challenging, as it requires accounting for nonlinear dynamics and light-cone projection...
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ALAIN BLANCHARD (IRAP , OMP)05/11/2025 17:40
Although the existence of dark matter is widely accepted, its true nature remains unknown, motivating alternative explanations such as \textbf{Modified Newtonian Dynamics (MOND)}. MOND modifies Newton’s laws for low accelerations (around $a_0 \sim 1.2 \times 10^{-10}\,\mathrm{m/s^2}$) and generally reproduces the flat rotation curves of galaxies.
However, recent \textit{Gaia} data reveal a...
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Pauline Zarrouk05/11/2025 18:00
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Louise Musset06/11/2025 09:40
Scattering Transforms are a type of summary statistics developed for the study of highly non-Gaussian processes. These statistics can be used to build generative models of data, and even to develop new component separation techniques. In this seminar, I will first give a general introduction to these tools. Then, I will show how they can be used for generative models of physical fields, with...
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Elsa Teixeira (LUPM Montpellier)06/11/2025 10:10
The persistent discrepancy between theoretical predictions of the standard cosmological model and precision measurements from various observational probes remains a significant challenge in modern cosmology. Over the past decade, mounting evidence for persistent discrepancies in the inferred values of cosmological parameters derived from both model-dependent and -independent methodologies has...
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Giulio Fabbian (Institut d'Astrophysique Spatiale (IAS))06/11/2025 10:30
Cosmology is entering a new high precision era with the beginning of the operations of next generation ground-based CMB experiments (Simons Observatory, SPT) and galaxy surveys (Euclid, Rubin, DESI). These experiments will deliver high-sensitivity data sets on large sky fractions and will enable us to constrain cosmology and astrophysics on all scales.
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In this talk I will focus on how galaxy... -
Christophe Yeche06/11/2025 11:30
The Dark Energy Spectroscopic Instrument (DESI) is building the largest 3D map of our universe to measure its expansion history over the past 11 billion years, and thereby, study dark energy. Over a five-year period, DESI will spectroscopically classify nearly 40 million galaxies and quasars over 1/3 of the sky and to redshifts z < 3.5.
The DESI collaboration has completed measurements of...
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Dr Thomas Colas (DAMTP - University of Cambridge)06/11/2025 12:10
Open effective field theories seek to incorporate dissipation and noise into our effective descriptions of gravity. These effects arise from the incomplete modelling of unknown components, which can significantly alter the dynamics of observable degrees of freedom. In this talk, I will introduce a framework that extends the standard effective field theory of dark energy, recovering it as a...
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Angus Wright (Ruhr University Bochum)06/11/2025 14:20
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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Adélie Gorce06/11/2025 15:00
The brightness temperature of the 21cm spectral line of neutral hydrogen is directly proportional to the cosmic baryon density and the neutral fraction of the IGM. By measuring this signal at different frequencies, one can map the IGM at any given redshift, and follow the formation and evolution of cosmic structures. As such, the 21cm signal is an exceptional tracer of both cosmology and the...
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Théo Simon06/11/2025 15:30
In this talk, I will first present the paradigm of the effective field theory of large-scale structure (EFTofLSS), a semi-analytical method which provides an accurate description of the power spectrum and bispectrum of bias tracers, and aims at improving cosmological constraints from large-scale structure surveys, a major challenge in the context of DESI and the forthcoming Euclid mission....
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William D'Assignies D.06/11/2025 16:30
I will present an overview of the 3×2pt analysis of the full 4000 deg² of imaging data from the final Dark Energy Survey data release (DES Y6). I will begin with a general introduction to the 3×2pt framework, outlining how cosmological parameters are inferred from the joint analysis of the three two-point correlations that can be measured from galaxy positions and shapes: galaxy clustering,...
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Julian Bautista (CPPM, Aix-Marseille Université, CNRS/IN2P3)06/11/2025 17:10
In this talk I will overview the preliminary cosmological results from the DESI Peculiar Velocity survey, using the first year of data. We measured about 100k peculiar velocities using the Tully-Fisher relation and the Fundamental Plane. We use auto and cross-correlations between our peculiar velocities and galaxy positions from the Bright Galaxy Survey at redshifts z < 0.1 to measure the...
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Madeleine Ginolin (IP2I/IN2P3/CNRS)07/11/2025 09:30
With around 3,000 published Type Ia supernovae (SNe Ia), ZTF is now the state-of-the-art low-redshift SN Ia sample. In the coming years, it will become the ideal sample to anchor Stage IV supernovae surveys, e.g. LSST.
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In this talk, I will review published results from the ZTF SN Ia DR2, for which the data are now publicly available. I will focus on discoveries concerning the astrophysical... -
Rodrigo Calderon07/11/2025 10:10
The ΛCDM model has been remarkably successful in describing the expansion history and structure of our Universe. Yet, recent high-precision observations are beginning to challenge this simple picture, suggesting possible departures from the cosmological constant, Λ. In this talk, I will discuss what current measurements reveal about the nature of dark energy, focusing on implications for the...
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Chloé Barjou-Delayre07/11/2025 10:40
The cosmological principle assumes the isotropy of the Universe. The high coverage of the Zwicky Transient Facility survey (ZTF) makes it possible to carry out an unprecedented study of the veracity of this principle by using observation of type Ia supernovae (SNe Ia).
This unique low redshift (z<0.15) survey with more than 3000 SNe Ia in the second data release (ZTF-DR2-SNe Ia) increases...
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Etienne Camphuis07/11/2025 11:30
I will present the most precise measurements of CMB temperature and polarization power spectra from SPT-3G observations of 4% of the sky during 2019-2020. Using the deepest CMB maps to date for a TT/TE/EE analysis, we achieve the most precise measurements of the lensed EE and TE spectra at small angular scales. These results provide strong confirmation of the ΛCDM model and yield cosmological...
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Aurélien Verdier (Ecole Polytechnique Fédérale de Lausanne (EPFL))07/11/2025 12:10
The Cosmology Redshift Survey of the 4-metre Multi-Object Spectroscopic Telescope (4MOST-CRS) will provide the most extensive spectroscopic redshift catalogue of galaxies and quasars over 5700 deg² in the southern hemisphere.
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As targets for the 4MOST-CRS, we present a selection of a sample of Bright Galaxies (BG) and Luminous Red Galaxies (LRG) in the redshift ranges $0.1<z<0.5$ and... -
Constance Ganot07/11/2025 12:30
Type Ia Supernovae (SNe Ia) are standardisable candles used to measure cosmic distances from their nearly constant maximum luminosity. Standardisation methods have been developed to reduce intrinsic scatter and improve distance estimates. Traditional photometric method reaches a ~0.15 mag precision, but the SNFactory (SNf) survey has suggested that a spectroscopic approach can reach ~0.07...
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Isaac Tutusaus
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Angus Wright (Ruhr University Bochum)
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Marina Ricci (LAPP)
The Vera C. Rubin Observatory is set to significantly advance our understanding of the Universe in the coming decade. It is now entering its final commissioning phase prior to the start of the 10-year Legacy Survey of Space and Time (LSST). In this talk, I will discuss the observatory’s progress and share some of the first results emerging from the analyses of early commissioning data.
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Marta Spinelli
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Giulio Fabbian
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