The late-time modifications of the ΛCDM model can be parametrized by three functions describing the expansion history and gravitational effects on light and matter in the Large Scale Structure. I will discuss what we learned from the first joint Bayesian reconstruction of these three functions from recent cosmological observations, particularly, the implications for modified gravity theories...
The concordance model in cosmology, ΛCDM, performs extremely well in accounting for most current cosmological observations with high accuracy.
However, the model faces several tensions with recent cosmological data and their increased accuracy. The discrepancy between the values of the Hubble constant H0 obtained from direct distance scale measurements and the cosmic microwave background...
We analyse the clustering of matter on large scales in an extension of the concordance
model that allows for spatial curvature. We develop a consistent approach to curvature and wide- angle effects on the galaxy 2-point correlation function in redshift space. In particular we derive the Alcock-Paczynski distortion of fσ8, which differs significantly from empirical models in the literature.
A...
In the current era of precision cosmology, the emergence of crucial tensions in the determination of the universe expansion has led to a twofold need to determine a criterion for combining different probes in a physically meaningful way, and to extend the mapping of the expansion of the universe to include data at redshifts not currently covered. In this talk, I will present recent...
Neutrinos are ubiquitous in cosmology and play a significant rule throughout the history of the Universe. As a result, cosmological observations offer a unique opportunity to test the properties of neutrinos. Standard model neutrinos are expected to freestream ever since they decouple from the primordial plasma in the early Universe. There are however multiple feasible particle physics...
Galaxies are biased tracers of the underlying dark matter density field. If we work with a single tracer, its two-point function will be symmetric under exchange of the pair of galaxies under consideration. But if we look at two different tracers, then in principle their cross-correlation could be not symmetric (Dai et al. 2016). This locally antisymmetric signal arises naturally when the two...
Line-of-sight (LOS) effects in strong lensing -- weak distortions to an image induced by the presence of objects such as dark matter haloes along the LOS -- have long been considered a nuisance when it comes to analysing strong lensing images. However, it was recently proposed that LOS shear could become a cosmological observable in its own right, if it could be accurately obtained from a...
Extracting cosmological information from observables is a daunting task. In particular, the peculiar velocity of the observer affects a large set of observables, including redshift, time intervals and angles. In the first part of my talk, I will briefly discuss two important tensions that appeared between early and late Universe probes, which are the Hubble tension and the cosmic dipole...
In this talk I will present the effects of gravitational lensing induced by the motion of massive objects. This is a relativistic effect and is much weaker than the deflection of light by density inhomogeneities. I will first discuss the effects of gravitational lensing by density perturbations and then generalise this to other possible inhomogeneities that may exist in our Universe, vector...
Upcoming surveys of cosmic structures will probe scales ranging from the nonlinear regime to scales close to the cosmological horizon. This opens up the possibility of probing the LCDM model, as well as early universe scenarios, with non-Gaussianity. Modeling the galaxy bispectrum is challenging, as it involves general relativity, radiation, and large nonlinearities. In this talk, I will...
