Gravitational wave (GW) standard sirens are well-established probes with which one can measure cosmological parameters, and are complementary to other probes like the cosmic microwave background or supernovae standard candles. I will focus on dark GW sirens, specifically binary black holes (BBHs) for which there is only GW data. Relying on the assumption of a source mass model for the BBH distribution, we consider four models that are representative of the BBH population observed so far.

I will discuss classes of hidden symmetries of gravity and their consequences for black holes and compact objects. 

Light dark matter candidates, such as axions and hidden photons, call for new ideas in direct detection. I discuss the recently proposed strategy of searching for e.g. axions using tunable cryogenic plasmas. The plasma haloscope enables resonant conversion by matching the axion mass to a plasma frequency, therefore converting axions to plasmons. Metamaterials are promising candidates, as the plasma frequency can be tuned. Besides axions, other dark matter candidates, such as hidden photons and scalars, can be successfully targeted with a plasma haloscope.

Langevin equation, Markovian process, multiplicative noise, Fokker-Planck equation, Schwinger-Keldysh formalism and much more... During this seminar, almost organised as a lecture, you will embark on a journey into the world of stochastic processes, with focus on their applications in the early Universe in the context of so-called stochastic inflation. We will begin by discussing how stochasticity emerges from the coarse-graining procedure, necessary to describe the effective dynamics of the largest cosmological scales that are affected by the quantum nature of the small-scale fluctuations.

Upcoming Large-Scale Structure surveys will likely become the next leading sources of cosmological information, making it crucial to have a precise understanding of the influence of baryons on cosmological observables. The Effective Field Theory of Large-Scale Structure (EFTofLSS) provides a consistent way to predict the clustering of dark matter and baryons on large scales, where their leading corrections in perturbation theory are given by a simple and calculable functional form even after the onset of baryonic processes.