Conveners
Invited talks
- Camille Bonvin ()
Invited talks
- Stefano Camera (Universita degli studi di Torino)
Invited talks
- Nastassia Grimm (University of Geneva)
Invited talks
- Julien Carron ()
Invited talks
- Chris Clarkson (Queen Mary University of London)
Invited talks
- Martin Kunz ()
Invited talks
- José Fonseca (Institute of Astrophysics and Space Sciences)
General relativity has been tested in the solar system and with other astrophysical observations and passed all tests with flying colours. However, these were essentially tests of the vacuum Einstein equations. Cosmology is different. Not only do we test GR on much larger scales, but it is also a very essential non-vacuum solution of the theory.
Observing LSS we cannot only measure the...
In this talk I will review recent work on understanding the importance of GR effects in the correlation function or power spectrum of spectroscopic data, with an emphasis on Infra-Red cancellations and their physical meaning. I will then discuss how any quantitative accurate statement about GR effects cannot be made without taking into account a large number of observational effects that...
Forthcoming weak lensing and galaxy clustering surveys, such as Euclid and LSST, offer unprecedented statistical precision. If new physics is to be discovered from these data sets, standard analysis methods that have previously sufficed must be carefully scrutinised. I will present recent calculations of several subtle biases that arise from neglecting non-linearity in the underlying density...
In this talk I will present a new methodology to measure the Weyl potential, which is the sum of the spatial and temporal distortions of the Universe's geometry, in a model independent way. I will then present how combining galaxy clustering and galaxy-galaxy lensing data from the Dark Energy Survey Year 3 measurements we can provide the first direct measurement of the evolution of the Weyl...
Massive galaxies, acting as gravitational lenses, can form greatly distorted images of background galaxies in so called strong lensing events. When background galaxy and lens are almost aligned along the line of sight, the image take the shape of an Einstein ring whose shape encodes basic properties of the lens. However, since lenses are not isolated objects in an otherwise perfectly...
In this talk I will discuss several new probes and considerations for large-scale structure measurements, which go beyond the most common 2x3pt shear and galaxy clustering measurements for cosmology. Firstly, I will discuss newly discovered cross-correlations between gravitational shear and flexion, including their surprising anticommutative properties. Secondly, I will discuss our latest...
Going beyond linear perturbation theory in cosmology brings several novel phenomena, among which the unavoidable mixing of scalar and tensor perturbation modes. While some of such effects - such as the generation of the so-called Scalar-Induced-Gravitational-Wave background - are nowadays quite popular and largerly analyzed, there are other effects which are less known and deserve...
Is it possible to construct a detailed model of local spacetime in a completely model-independent and non-perturbative manner? Specifically, this would involve developing an observationally viable and physically meaningful method for identifying and classifying angular distortions present in the distance-redshift relation, without relying on the cosmological principle or the notion of peculiar...
In my presentation I will start with an overview of the Euclid satellite, discuss its current status and show some recent early results. I will then give a brief outlook of the expected science results in the coming years.
Gravitational redshift and Doppler effects give rise to an antisymmetric component of the galaxy correlation function when cross-correlating two galaxy populations or different tracers. Relativistic effects can be isolated from density and redshift space distortions (RSDs) clustering signals by splitting the galaxy population into two catalogs and using adapted estimators, such as the dipole...
A homogeneous spherical cloud of pressureless matter ( M ) at rest will eventually collapse into a black hole characterized by its gravitational radius ( R_s = 2GM ). This forms what we term a Black Hole Universe (BHU). The BHU necessitates a boundary term to ensure that nothing can escape ( R_s ). This boundary term modifies Einstein’s field equations by adding a component that behaves...
Galaxy clustering provides a powerful way to probe cosmology. This requires understanding of the background mean density of galaxy samples, which is estimated from the survey itself by averaging the observed galaxy number density over the angular position. The angle average includes not only the background mean density, but also the monopole fluctuation at each redshift. Here for the first...
A new avenue was recently developed for analyzing large-scale structure data with a model-independent approach, in which the linear power spectrum shape is parametrized with a large number of freely varying wavebands rather than by assuming specific cosmological models. Here we show, using a Fisher matrix approach, that the precision of this method for the case of the one-loop power spectrum...
Large-Scale Structure cosmology has made tremendous progress in the last few years, and is now able to place constraints on cosmological parameters with a precision rivalling that achieved by CMB experiments. In this process, the concordance Lambda CDM model has been shown to provide a very reasonable description of the evolution of the Universe's structure and expansion at late times....
Quadratic estimators (used notably for current most precise CMB lensing measurements) are a wide class of estimators efficient in capturing small signals of anisotropies. They will provide sub-percent contraints on the growth structure in the near future. After discussing how these estimators relate to bispectra, I will describe a general expansion of spherical (full-sky) bispectra into a set...
First-order gravitational lensing is a pure gradient, and hence only gives image magnification and shear. But post-Born corrections give rise to an additional small image rotation. I discuss the impact of this rotation on galaxies and the CMB temperature and polarization, and explain the challenges in trying to measure it. The rotation is somewhat enhanced for CMB lensing due to the large...
In this talk, I would like to highlight some key results from our RayGal studies of the impact of general relativistic effects on the apparent distribution of large-scale structures down to non-linear scales. We have investigated the dipole of the halo-halo cross-correlation from the 150 Mpc/h scale to the 5 Mpc/h scale. At large scales, we recover the linear expectation while at scales...
The current concordance model of cosmology has been extremely successful in constraining the global properties of the universe. However, it is based on the assumption of statistical homogeneity and isotropy, and we are thus lead to test this global geometry. In practice, it is sufficient to constrain mild anisotropies, and I will show how anisotropy can be considered as a special...
Real-time measurements are becoming feasible in cosmology, where the next generation of telescopes such as the Square Kilometer Array and the Extremely Large Telescope will detect the temporal change of redshifts of individual sources with a precision that will allow a direct detection of the cosmic expansion rate. These detections of cosmic drifts of redshifts are likely to become...
