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Pierre Antilogus (LPNHE)17/11/2022 09:30Invité
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Stephanie Escoffier (CPPM)17/11/2022 10:00Invité
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Matthew Pieri (Laboratoire d'Astrophysique de Marseille)17/11/2022 11:00Invité
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Pauline Zarrouk (LPNHE)17/11/2022 11:30
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Nicolas Martinet (LAM/CNES)17/11/2022 11:50
Recent cosmic shear studies have shown that higher order statistics (HOS) developed by independent teams now outperform standard two-point estimators due to their sensitivity to non-Gaussian features of the large-scale structure. The use of such non-Gaussian estimators is being evaluated in Euclid by the Higher Order Weak Lensing Statistics (HOWLS) team. I will present the most recent results...
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Lisa Goh (CosmoStat, CEA Paris-Saclay)17/11/2022 12:10
We introduce a tomographic coupled dark energy model, an extension of the coupled quintessence model in which coupling strength between the scalar field, playing the role of dark energy, and dark matter particles, is allowed to vary with redshift. We bin the redshifts and let coupling vary within each tomographic bin, subsequently testing 3 different binning regimes where the choice of bin...
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Sophie Henrot-Versille (IJCLab/IN2P3/CNRS)17/11/2022 14:00Invité
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Dr Katarina Krajlic (LAM)17/11/2022 14:20Invité
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Florent Leclercq (Institut d'Astrophysique de Paris)17/11/2022 14:40Contribué
I will discuss perspectives for building accelerated forward data models of galaxy surveys. In particular, I will introduce a perfectly parallel approach to simulate cosmic structure formation, based on the spatial COmoving Lagrangian Acceleration (sCOLA) framework. Building upon a hybrid analytical and numerical description of particles' trajectories, sCOLA allows an efficient tiling of a...
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Julien Bel (CPT)17/11/2022 15:00
We analyse the clustering of matter on large scales in an extension of the concordance
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model that allows for spatial curvature. We develop a consistent approach to curvature and wide-
angle effects on the galaxy 2-point correlation function in redshift space. In particular we derive the
Alcock-Paczynski distortion of fσ8, which differs significantly from empirical models in the... -
Basheer Kalbouneh (Aix-Marseille university/ CPT)17/11/2022 15:20
The failure to converge on a consensus value of Hubble's constant triggered investigations into the reliability of geometric descriptions of the local spacetime that deviate from the standard cosmological metric. The question that arises is whether metrics with lower symmetries, while still simple, provide a reliable description of the data in the local patch of the universe where global...
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Corentin Ravoux (CPPM)17/11/2022 15:40
I will present the one-dimensional Lyman-alpha forest power spectrum measurement using the first data provided by the Dark Energy Spectroscopic Instrument (DESI) (Ravoux et al. in prep.). The data sample comprises quasar spectra at redshift z > 2.1, contained in the DESI Early Data Release (EDR) and the first two months of the main survey. This first set of data already yields an improvement...
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Jean-Charles Cuillandre (CEA Saclay)17/11/2022 16:30Invité
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Matthieu Tristram (IJClab, CNRS, France)17/11/2022 17:00Invité
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federico piazza (CPT, Marseille)17/11/2022 17:20
In the presence of important fluctuations in the gravitational field causality can be studied by calculating an "average distance". I will show that such an average distance is "sub-additive" as opposed to standard geodesic distances of a classical spacetime which are always strictly additive.
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Irina Dvorkin (Institut d'Astrophysique de Paris)18/11/2022 09:00Invité
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Johan Richard (CRAL)18/11/2022 09:20Invité
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Dr Vincent Reverdy (Laboratoire d'Annecy de Physique des Particules)18/11/2022 09:50
Galaxy clusters and dark matter halos constitute a building block of many cosmological analyses. However, amongst simulations and observations, there is a wide variety of definitions of what a cluster is from a physical standpoint that do not necessarily match with each other. On top of that, on the algorithmic side, detection strategies can vary greatly from traditional friend-of-friend...
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Christophe Yeche (CEA Irfu/SPP)18/11/2022 10:10
DESI has started its observation program since May 2021. It has demonstrated its ability to complete its program in less than 5 years. From 2025 will begin a phase of transition which will finish in 2028 with DESI-II.
DESI-II will have for first objective to cover a zone in redshift little covered by DESI, in the 2<z<4 range. We will use as tracers of the matter, Lyman-Break Galaxies. The...
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Mathew Smith (IP2I/IN2P3/CNRS)18/11/2022 11:00Invité
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Dr Jonathan Freundlich (Université de Strasbourg)18/11/2022 11:30Invité
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Bastien Carreres (CPPM)18/11/2022 11:50
Type Ia supernovae are known to be standard candles, which means that we can infer their distance from their flux measurement and build their Hubble Diagram. Peculiar velocities can be retrieved from the Hubble Diagram residuals, but until now the statistics of SN Ia was too low to use these velocities as a cosmological probe. With the next generation of surveys (LSST, ZTF) the statistics of...
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Rémy KOSKAS (Observatoire de Paris, LUTH)18/11/2022 12:10
Halo Dark Matter (DM) Formation is a complex process, intertwining both nonlinear gravitational and cosmological phenomena.
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One of the manifestations of this complexity is the shape of the resulting present-day DM halos : simulations and observations show that they are triaxial objects. Interestingly, those shapes carry cosmological information; We prove by two different methods that... -
Julian Bautista (Aix-Marseille Univ, CPPM)18/11/2022 14:00
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Marta Spinelli (INAF-OATs)18/11/2022 14:20Invité
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Isaac Tutusaus (IRAP)18/11/2022 14:40
Galaxy surveys provide one of the best ways to constrain the theory of gravity at cosmological scales. They can be used to constrain the two gravitational potentials encoding time, Ψ, and spatial, Φ, distortions, which are exactly equal at late time within General Relativity. Hence, any small variation leading to a non-zero anisotropic stress, i.e. a difference between these potentials, would...
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Prof. ALAIN BLANCHARD (IRAP , OMP)18/11/2022 15:00
The Hubble tension, given the observed local measurement by SH0ES is known to be one of the major tension that the standard LCDM is facing. The recent results from Pantheon+ combined with the value inferred from SH0ES lead to a value of the reduced cosmological density parameter, $\omega_m$ that conflicts with the value inferred from the CMB for the LCDM model. However the situation does...
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Dr Amandine Le Brun (PSL & Observatoire de Paris)18/11/2022 15:20Contribué
The dark matter halo sparsity, i.e. the ratio between spherical halo masses enclosing two different overdensities, provides a non-parametric proxy of the halo mass distribution which has been shown to be a sensitive probe of the cosmological imprint encoded in the mass profile of haloes hosting galaxy clusters. Mass estimations at several overdensities would allow for multiple sparsity...
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Laurence Tresse (LAM)18/11/2022 15:40Contribué
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