Research

My research activities began with a focus on cosmological perturbation theory and the clustering of cosmic matter. Alongside mainstream contributions on the structure of peculiar velocity fields in the local universe, and the shape of the halo occupation number and of the mass to light ratio of cosmic structures, I also ventured beyond the standard paradigm, advancing an original gravitational hypothesis for the coupling between dark and baryonic matter.

I then transitioned toward large observational programmes, becoming a core member of landmark redshift surveys launched in the early 2000s — DEEP2 at Keck, and VIMOS, VIPERS, and zCOSMOS at the VLT — which opened a new window onto the deep universe. A cornerstone of this effort was the development of an original three-dimensional Voronoi-Delaunay algorithm, capable of identifying gravitationally bound galaxy groups and tracing the large-scale density field in a way that is adaptive, parameter-free, and naturally suited to the sparse, flux-limited geometry of deep redshift surveys. An important scientific outcome was the first estimate of the time evolution of the non-linear bias between matter and light densities, which in turn allowed placing strong constraints on redshift space distortions.

From around 2010, I turned my interests to dark energy, and notably to designing original cosmological tests aimed at constraining its nature using rich redshift surveys. Some of these tests are purely geometrical, exploiting the statistical symmetry of pairs of galaxies; others are dynamical, leveraging gravitational instability and the large-scale arrangement of galaxies. Alongside this, I also explored the phenomenology of modified gravity scenarios through the development of flexible parametrisations, and worked to establish a bridge between Effective Field Theory descriptions of gravity and their observational signatures, with a particular eye toward the constraining power of forthcoming surveys such as Euclid, and grounded in specific modified gravity proposals including the broad class of Horndeski theories.

My current research targets one of the deepest pillars of the standard cosmological model: the cosmological principle, now under scrutiny as observational tensions continue to accumulate. I designed, and applied to data, the first method capable of testing whether an arbitrary cosmic observer perceives an isotropic universe, deliberately freeing such analyses from their traditional anchoring in the Earth-centred frame. I also proposed an original strategy to detect the real-time evolution of the cosmic metric, by tracking our proper acceleration through cosmic space and its imprint on the sky: a measurable secular drift in the positions of distant quasars. This programme directly addresses whether the CMB dipole is of kinematic origin — one of the most consequential open questions in modern cosmology. I further introduced a novel observable, the Expansion Rate Fluctuation Field, conceived to detect and characterise potential anisotropies in the Hubble diagram in a fully model-independent manner. This phenomenological programme is complemented, on the theoretical side, by ongoing work to extend and systematise the covariant cosmographic formalism, equipping it to interpret eventual signatures of cosmic anisotropy within beyond-FLRW metric frameworks.