Cosmological observations have long shown 85% of the mass in the universe is composed of
dark matter, i.e., a substance that does not emit and reflect light, while the known matter constitutes the remaining 15%. Identifying the nature of dark matter is one of the central tasks in science. Over the past forty years, physicists have assumed that dark matter is made of new particles that are non-interacting. Despite the great success of this hypothesis in explaining overall structure of the universe, it fails to accommodate detailed observations in galaxies. Understating and resolving this so-called “the small-scale crisis” have been a driving force in the field of astrophysics.
The crisis may indicate a paradigm shift is required, i.e., the prevailing hypothesis is inaccurate in describing the inner structure of galaxies. In this project, we plan to explore a new dark matter theory, Self-Interacting Dark Matter, where dark matter particles have strong self-interactions. We will use numerical simulations and analytical modelling to study predictions of dark matter self-interactions in galaxies and compare them with astronomical observations. In particular, we will focus on large spiral galaxies, small satellite galaxies in the Milky Way, and newly-observed ultra-diffuse galaxies. In these systems, dark matter distributions exhibit a great diversity that challenges the prevailing theory most seriously.
The project will lead to at least 5 high-quality research papers, and they will be published in major peer-reviewed journals in the fields of astrophysics and cosmology. The findings will be presented at research conferences, workshops and seminars. The proposed work will significantly advance our understanding of the nature of dark matter.