Study Advances Galaxy-Halo Connection Models for Modified Gravity Theories Using Survey Simulations
Researchers used hydrodynamical simulations of f(R) modified gravity to study how galaxies connect to underlying dark matter halos, a key uncertainty for interpreting data from large galaxy surveys like DESI and Euclid. The study found that standard models underestimate galaxy clustering by 10-20% when assembly bias is ignored, and that modified gravity introduces additional complexity through screening mechanisms. This work is important because accurately modeling the galaxy-halo connection is essential for using upcoming surveys to test alternative theories of cosmic acceleration.
A new preprint on arXiv presents detailed simulations examining the galaxy-halo connection in f(R) modified gravity theories, which propose alternatives to dark energy for explaining the universe's accelerated expansion. Using state-of-the-art hydrodynamical simulations matched to the specifications of Stage-IV surveys (DESI and Euclid), the researchers generated mock catalogs of emission line galaxies and luminous red galaxies to study how galaxy properties depend on their host dark matter halos. The analysis reveals that the chameleon screening mechanism in modified gravity, combined with galaxy formation physics, creates complex imprints on the galaxy-halo connection. The standard halo occupation distribution model, which assumes galaxy occupation depends only on halo mass, underestimates clustering strength by 10-20% at low redshifts when assembly bias is neglected. By introducing environment density as a secondary variable in the model, the researchers reduced assembly bias effects to 2-3% for redshifts below 0.5, providing a foundation for improved cosmological tests with modified gravity.
What's missing
The study does not discuss how results compare to observational constraints from current surveys, nor does it address computational costs or practical implementation challenges for applying these improved models to real survey data analysis pipelines.
What different sources said
- arXiv astro-phCenter
Galaxy formation in modified gravity -- II. galaxy halo connection and assembly bias
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