Séminaire Univers /
Seminar Universe

Combining Cosmic Microwave Background (CMB) observations with large-scale structure (LSS) surveys provides a powerful lever arm to probe the growth of structure from recombination to the present epoch, test gravity on cosmological scales, and constrain the properties of dark matter and dark energy.

In this talk, I will present the first cosmological analysis of galaxy clustering using the Euclid Q1 data release, together with its cross-correlation with CMB lensing convergence maps from Planck and the Atacama Cosmology Telescope. We detect the cross-correlation signal at high significance and find excellent agreement with predictions from simulations and the Planck 2018 ?CDM cosmology.

I will discuss a comprehensive set of robustness tests against observational systematics, tomographic measurements across redshift bins, and initial constraints on galaxy bias and photometric redshift uncertainties. These results highlight the strong potential of Euclid–CMB cross-correlations as a robust cosmological probe and as a powerful tool to control systematics in forthcoming Euclid data releases.