Develop self-consistent modified gravity simulations

Background: The current end-to-end pipeline uses a General Relativity (GR)-based catalogue for the halo population, while testing for modifications to gravity in the gravitational redshift signal. Departures from GR affect both the signal and the underlying structure formation.

Question / Future Work: It is crucial to develop and utilize high-resolution modified-gravity simulations that populate halo catalogues self-consistently with member galaxies to accurately model structure formation in alternative gravity theories that remain viable after GW170817.

Why It Matters: Ignoring self-consistent structure formation in modified gravity may introduce model biases that become significant as statistical errors decrease.

Evidence: Our results also underscore the need for high-resolution modified-gravity simulations in large volumes: departures from GR affect not only the gravitational redshift signal but also the halo population itself, which in this work is still drawn from a GR-based catalogue. In this context, it is crucial to develop halo catalogues in modified gravity that are populated self-consistently with member galaxies.