Speaker
Description
The $\Lambda$CDM model is the most widely accepted model of cosmological structure formation and evolution. It includes a form of Cold Dark Matter (CDM), which is non-quantum, non-relativistic and collisionless. It settles into extended and dense self-gravitating haloes as a result of cosmic structure formation. CDM haloes act as a stabilizing agent for galaxies, while the late-time accelerating expansion of the Universe is sourced by a cosmological constant $\Lambda$. Due to the disagreement between $\Lambda$CDM-based simulations and observations on galactic and sub-galactic scales and the fact that traditional dark matter candidates remain undetected, the theoretical space for alternatives has been widening, making the particle nature of dark matter a fundamental question in Physics.
In the Self-Interacting Dark Matter (SIDM) model, strong self-interactions modify the inner dynamics of dark matter haloes and could potentially solve outstanding inconsistencies between CDM and observations of dwarf galaxies. We focus on the final stage of the SIDM halo evolution - the "gravothermal collapse" phase. We show that in a certain region of the parameter space of SIDM models, dwarf-size SIDM haloes have a bimodal distribution, with some having central density cores and others being centrally cuspy; the latter being those that have collapsed and contain an intermediate-mass black hole. This offers a promising solution to the so-called "diversity problem" in Milky-Way satellites. We extend the analysis of the core-collapse phase in SIDM haloes towards including the impact on the baryonic component within. In particular, we discuss how the use of adiabatic invariants can be exploited to predict the response of stellar orbits to the collapsing SIDM core. Furthermore, we study the impact of gravothermal collapse on the formation and evolution of dwarf-size galaxies with idealised/controlled simulations using the AREPO code.
