Study Advances Galaxy-Halo Connection Models for Modified Gravity Theories Using Survey Simulations
Researchers have developed improved mock galaxy catalogues in modified gravity models to better understand how observed galaxies relate to underlying dark matter halos, finding that standard models underestimate galaxy clustering by 10–20%. The work uses state-of-the-art hydrodynamical simulations tailored to match specifications of major ongoing surveys such as DESI and Euclid. Reducing this systematic error is critical for accurately testing alternatives to the cosmological constant as explanations for the Universe's accelerated expansion.
A new preprint study examines the galaxy-halo connection — the statistical link between observable galaxies and the unobservable dark matter halos they inhabit — within the context of modified gravity (MG) models, specifically f(R) gravity. Using hydrodynamical simulations, the authors generated mock catalogues of emission line galaxies and luminous red galaxies designed to match Stage-IV survey specifications. They confirm that the standard halo occupation distribution (HOD) model, which ties galaxy occupation solely to halo mass, underestimates galaxy clustering by 10–20% at redshifts below 1 when assembly bias is ignored, and show that modified gravity introduces additional complexity through mechanisms such as chameleon screening. A key finding is that halo and galaxy formation are progressively enhanced for more massive halos over time in MG scenarios. By incorporating local environment density as a secondary HOD variable, the team reduces the assembly bias effect to just 2–3% at redshifts below 0.5, providing a more robust starting point for testing non-standard cosmological models with large-scale structure data.
What's missing
The study is a preprint and has not yet undergone peer review. The analysis is limited to f(R) gravity as a representative modified gravity model; it is unclear how well the proposed HOD extension generalises to other MG frameworks. The robustness of the environment-density secondary variable across different simulation codes and galaxy formation prescriptions is not fully explored.
What different sources said
- arXiv astro-phCenter
Galaxy formation in modified gravity -- II. galaxy halo connection and assembly bias
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