We present a new approach to model the gravitational dynamics of large-scale structures, where we follow the evolution of the probability distribution of the displacement field. This provides a nonperturbative scheme that goes beyond shell crossing and the truncations of the power spectra on nonlinear scales directly arise from the equations of motion. Although the density power spectrum is...
I will discuss some of the applications of called scale-free models to the problem of non-linear structure formation: as a tool to control the accuracy of measurements from numerical simulations, as a tool for precision testing of theoretical approaches to matter clustering, and more generally as a tool to better understand and model clustering in standard cosmological models
Compact binary systems that emit detectable gravitational waves, such as binary black holes and binary neutron stars, can be used as "standard sirens" to constrain cosmological parameters. This talk will review cosmological results obtained from the most recent gravitational wave observations, with a focus on the most stringent constraints produced by the LIGO-Virgo-KAGRA Collaboration, while...
Theoretical and observational challenges to standard cosmology such as the cosmological constant problem and tensions between cosmological model parameters inferred from different observations motivate the development and search of new physics. A less radical approach to venturing beyond the standard model is the simple mathematical reformulation of our theoretical frameworks underlying it....
The LCDM is expected to face two significant "tensions", one on H0 and the other on S_8. I will discuss these two tensions to assess whether current observational data are at a sufficient level to conclude that LCDM is excluded.
I will present how screening could (or could not) occur in two-field models of the axio-dilaton type and
present a simplified analysis of their cosmology.
In the coming decades, large observational efforts will allow us to map the distribution of the large scale structure in the evolved Universe, a.k.a. the cosmic web. The major purpose of these efforts is to extract the cosmological information present in the observed density fluctuations. However, from observations of the Cosmic Microwave Background, we know that there are also fluctuations on...
I will discuss the role dark matter subhalos may play in unveiling or constraining both the nature of dark matter and the properties of the primordial power spectrum on small scales. This is a topic in which semi-analytical predictions can be made without resorting to cosmological simulations, in the regime where dark matter subhalos are too light to accrete baryons, as expected in the cold...
Although it looks mathematically simple, the Schwarzschild metric describes a complicated spacetime that is endowed with two asymptotic regions and two singularities. When including electric charge and spin, other black hole metrics are even more complicated. Although causal diagrams help to figure out what an observer can possibly see, it is almost impossible to guess how different regions of...
I'll present recent results showing that getting a bounce by means of quantising the background may yield to a mild ambiguity on the spectral index of the perturbations, and a more serious one on its amplitude. We trace the origin of this issue to the fact that quantising and applying a canonical transformation do not commute.
I will discuss topology in the electroweak model.
The lack of convergence to a consensus value for the Hubble constant has triggered a search for the reliability of non-standard cosmological line elements. The question is whether metrics with a lower degree of symmetry than FRW, while remaining simple, provide a reliable description of the data in the local part of the universe where the global uniformity is violated. We address this problem...
