Exploring Dark Matter Non-Gravitational Interactions through Cosmological Data
speaker: Lei Zu (NAOJ)
Abstract:
Possible non-gravitational interactions between dark matter (DM) and standard model particles could leave distinctive signatures on cosmological observables, providing a rare window into physics beyond the standard ΛCDM model. If DM interacts with baryons or neutrinos before decoupling, it induces distortions in the cosmic microwave background (CMB) and large-scale structure, and gives rise to dark acoustic oscillations (DAO) on small scales (k ~ 1 h/Mpc). These scales can be directly probed by weak lensing surveys, which trace the underlying matter distribution. To investigate this, we develop an emulator based on N-body simulations with initial conditions including DAO features. Using DES Y3 cosmic shear data, our emulator maps the linear to nonlinear matter power spectrum, enabling robust predictions of the shear signal. We show that constraints on DM–baryon interactions improve by up to a factor of five compared to Planck alone. Moreover, by combining ACT data, we identify a nearly 3σ preferred region for DM–neutrino interactions. Finally, we introduce a specific neutrino-portal DM scenario and demonstrate its potential to provide a good fit to the data.