Speaker
Description
How can we accurately test extensions to ΛCDM when unmodelled baryonic dynamics obscure the galaxy-halo connection? While galaxies are vital tracers of large-scale structure, residual uncertainties in their distribution often obstruct cosmological inference, especially in two-dimensional projections where halo-level information is incomplete. I present an analytic galaxy bias model in projection that incorporates stochasticity and non-locality at linear order while enforcing physical consistency.
By calibrating the model to hydrodynamical simulations, I demonstrate that it matches two-point statistics down to the simulation resolution and recovers the bispectrum down to 10 Mpc up to z=3. The model outperforms standard local bias approaches by capturing non-linearities driven by mode coupling and phase correlations across a wide range of halo masses. This framework improves the robustness of joint clustering and galaxy-galaxy lensing tests, allowing one to successfully separate astrophysical systematics from genuine scale-dependent structure growth. Finally, this model enables efficient field-level forward modelling of galaxy positions, providing a principled and practical route for simulation-based inference with upcoming surveys like Euclid and Rubin LSST.