Speaker
Description
The gravitational interaction between dark matter (DM) and baryons has long been ignored when building galaxies semi-empirically and observationally. In this talk, I will show that the baryonic gravity leads to an adiabatic contraction of DM halos, ignoring which would result in the built galaxies that are not in a dynamic equilibrium and hence cannot exist in reality. We propose a new approach to fitting galaxy rotation curves by numerically calculating the contraction of DM halos. We find adiabatic contraction makes DM halos more cuspy for massive galaxies, so that their rotation curves cannot be fit without systematically reducing baryonic contributions. We also examine the baryonic effect on the predicted radial acceleration relation of cold DM model, and find the predicted relations of massive galaxies are systematically higher than observed. Both tensions point to a core-cusp problem, a classical problem for dwarf galaxies but persisting in massive galaxies as well due to strong adiabatic contraction. In order to reconcile this problem, feedback must work in massive galaxies as efficiently as in dwarf galaxies.
| Do you plan to attend the symposium in-person or virtually? | in-person |
|---|
