Orateur
Description
The Euclid Quick Data Release (Q1) offers the first opportunity to test the cosmological potential of Euclid on real data. In this talk I will present the first cosmological analysis performed on Euclid data, based on the tomographic clustering of photometric galaxies in the three Euclid Deep Fields and their cross-correlation with CMB lensing from Planck and ACT. Despite covering only about 60 square degrees, the data already deliver a combined detection significance above 30σ. I will show how cross-correlating with CMB lensing provides a powerful handle on the systematics that affect early data, from imaging artefacts to photometric redshift errors, and how it helps break the degeneracy between galaxy bias and the growth of structure. The resulting constraints on the matter density, the amplitude of fluctuations and the growth factor are consistent with current state-of-the-art results, and reach comparable precision with a sky area hundreds of times smaller. These results provide a first glimpse of what Euclid, combined with CMB lensing, will achieve with its first major data release.