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...
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...
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...
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...
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.
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...
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...
Halo Dark Matter (DM) Formation is a complex process, intertwining both nonlinear gravitational and cosmological phenomena.
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...
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...
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...
