Toshiki Kurita - Probing Primordial Parity Violation with Intrinsic Galaxy/Halo Shapes (Pedagogical)

Abstract: The large-scale correlation of intrinsic galaxy and halo shapes in the Universe, known as intrinsic alignment, has recently been considered not only a major source of systematics in weak lensing analyses but also a tracer of the cosmological gravitational tidal field, potentially providing unique information on the early Universe. In this talk, I will introduce the potential of intrinsic alignment as a useful late-time observable for probing primordial parity violation. Tensorial observables, such as galaxy shapes, are sensitive to parity-odd signals at the level of two-point statistics, whereas scalar observables, like the galaxy density field, require four-point statistics to detect such signals. After motivating the use of galaxy shapes in this context, I will review measurements from observational data on intrinsic alignment and discuss relevant physical models. Finally, I will present recent results from our work on probing parity violation using perturbation theory and N-body simulations.