We argue that discreteness at the Planck scale (naturally expected to arise from quantum gravity) might manifest in the form of minute violations of energy-momentum conservation of the matter degrees of freedom when described in terms of (idealized) smooth fields on a smooth spacetime. In the context of applications to cosmology such `energy diffusion' from the low energy matter degrees of...
In several theoretical scenarios, a scalar field is introduced to model dark energy. While some properties of this scalar field can be constrained by cosmological observations, certain properties like its coupling with the standard model fields can be searched for with local experiments such as the ones testing for the universality of free fall and the ones using atomic clocks. Such...
Grâce aux mesures de lentillage gravitationnel et de clustering des galaxies, la prochaine génération de grands relevés (Euclid, LSST) posera des contraintes sans précédent sur l'Univers récent. D'autre part, des observations CMB de haute qualité (Planck et futures expérience) sont capables d'imposer des contraintes strictes sur l'Univers primordial. Je montrerai comment la combinaison et la...
In the era of the upcoming stage IV surveys, the sky will be more revealing than ever. In this talk, I will put the homogeneity scale in the general cosmological context. I will show how one can use the homogeneity scale as a standard ruler to learn about the large scale structures.
High-precision astrometric experiments might constrain our proper acceleration through space via real-time observations of the change in the aberration of sources at cosmic distances.
The cosmological component of this aberration drift signal, the non-inertial motion generated by the large-scale distribution of matter, can in principle be detected by
astrometric surveys. It can provide...
Type Ia Supernova (SNIa) distance measurement for cosmology is based on a well-established observational paradigm that two main effects explain their variabilities in luminosity: stretch (link to intrinsic properties), and color (link mainly to dust extinction). However, after correcting the luminosity of both stretch and color, an intrinsic scatter in luminosity and a correlation of Hubble...
The growth rate of cosmic structures is a powerful quantity to probe gravitational interactions and dark energy. In the late-time Universe the growth rate becomes non-linear, making it more difficult to probe, but also makes it in principle a source of additional cosmological information than its linear counterpart. In this talk, I will discuss why it becomes interesting to probe the growth...
