Speaker
Description
The Jeans model for self-interacting dark matter (SIDM) halos has been shown in recent literature to reproduce, with surprising accuracy, the spherically averaged halo profiles inferred from observations and simulations of relaxed galaxies and galaxy clusters. However, in general, dark matter halos are not spherically symmetric, owing to asymmetric baryon distributions and residual triaxiality from hierarchical assembly. Halo shapes therefore provide an important observational discriminant: in the dense interior, frequent SIDM scatterings isotropize particle velocities and erase the ellipticity characteristic of collisionless CDM halos. This distinction is especially relevant for massive galaxies, where baryons can cause SIDM and CDM halos to have nearly identical spherically averaged density profiles but still exhibit markedly different shape profiles. In this talk, I present recent work extending the Jeans model to describe SIDM density and shape profiles beyond spherical symmetry. I introduce a novel “squashed” Jeans model that captures the physical requirement that multiple scatterings are needed to modify halo shapes while remaining computationally inexpensive compared to full axisymmetric treatments. I then show results validating the squashed model against cosmological hydrodynamical simulations for both SIDM and CDM, and conclude with an application to Milky Way rotation curve data.
| Keyword-1 | Astrophysics |
|---|---|
| Keyword-2 | Dark Matter |
| Keyword-3 | SIDM |