CAREER: Towards realistic halo-scale constraints on the nature of dark matter and gravity

The nature of dark matter (DM) and gravity are among the foremost unsolved problems in astrophysics. To distinguish between the possible solutions, astrophysicists compare the observed distribution of galaxies to supercomputer simulations, which follow the formation and evolution of galaxies in “fake” Universes with different DM and gravity models. This team of investigators will create an ambitious simulation suite that uniformly covers an unprecedented range of DM and gravity models. The simulations will be publicly available and will enable detailed comparisons to observational surveys that are expected to release data during the 5-year lifetime of this award, potentially ruling out certain models of DM and gravity. This project will also support the mentoring of a postdoctoral researcher and a graduate student, as well as an exploration of novel tools such as 3D printing to teach cosmology to a wide range of learners. Enormous effort has been devoted to finding observable imprints of different DM and gravity models, but the work of different groups is most often impossible to inter-compare because they rely on different cosmological parameters, galaxy formation physics, simulation codes, and analysis tools. As a result, it is still unclear which model signatures are robust and which are degenerate with those of other models, cosmology, or poorly understood feedback processes. This project represents a systematic approach to searching for unique observable signatures on small scales, focusing on the density structure of (sub-)halos, the outskirts of galaxy clusters, and the distribution of satellite galaxies. The resulting simulation suite will be unique in its uniformity, its breadth of models, and its mass range from dwarf galaxies to clusters. The publicly available simulations will enable countless community projects. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.