The standard Lambda Cold Dark Matter (ΛCDM) cosmological model has proven remarkably successful in describing a broad range of observational data, ranging from the cosmic microwave background (CMB) radiation to the large-scale structure of the Universe. However, recent advances in precision cosmology have revealed persistent statistical discrepancies between independent data sets and...
Precessing black-hole mergers can produce an imbalance between right- and left-handed circularly polarized gravitational waves. According to the Cosmological Principle, such chiral emission should average out to zero across all binary mergers in our Universe in order to preserve mirror-reflection symmetry at very large scales. In this talk, I will show how gravitational-wave astronomy enables...
The two-body Decaying Dark Matter (DDM) model extends the standard cold dark matter paradigm by allowing dark matter particles to decay into a massive daughter particle and a relativistic species. This scenario arises naturally in particle physics and has testable implications for cosmological observables. In this talk, I will introduce the model and present updated constraints on the dark...
We present a framework that for the first time allows Bayesian model comparison to be performed for field-level inference of cosmological models. We achieve this by taking a simulation-based inference (SBI) approach using neural likelihood estimation, which we couple with the learned harmonic mean estimator in order to compute the Bayesian evidence for model comparison. We apply our framework...
Mapping the distribution of neutral atomic hydrogen (HI) in the Universe through its 21 cm emission line provides a powerful cosmological probe to map the large-scale structures and shed light on various cosmological phenomena. The Baryon Acoustic Oscillations at low redshifts can potentially be probed by sensitive HI intensity mapping experiments and constrain the properties of dark energy....
Mounting theoretical evidence suggests that the information stored in black holes suppresses their evaporation rate – a quantum effect known as memory burden. This phenomenon opens up a new window for small primordial black holes (PBHs) below $10^{15}\, \text{g}$ as viable dark matter candidates. In this talk, I will discuss observational signals from such small PBHs. Beyond constraints from...
\begin{abstract}
In this work, we investigate a cosmological model within the framework of ( f(Q,T) ) gravity, incorporating two-fluid dynamics composed of matter and radiation. The model is constructed using the anisotropic Bianchi type-I metric to explore the evolution of the universe in an extended gravitational theory where the non-metricity scalar ( Q ) is coupled with the trace of...
Based on ArXiv 2504.17680, B. Blachier, C. Ringeval (2025)
Cosmic inflation may exhibit stochastic periods during which quantum fluctuations dominate over the semi-classical evolution. Extracting observables in these regimes is a notoriously difficult program as quantum randomness makes them fully probabilistic. However, among all the possible quantum histories, the ones which are relevant...
