Title: Cosmological small-scale issues, and attempted solutions in cold and self-interacting dark-matter models

Speaker: Fangzhou Jiang (Kavli Institute for Astronomy and Astrophysics, Peking University)

Time: 13:30 pm, May 23 (Thursday) 2024

Venue: C302, New Science Building

Abstract: The standard cold dark-matter paradigm has been very successful in reproducing galaxy statistics on large cosmological scales. However, it confronts a series of challenges on sub-galactic small scales. Notably, the morphology of dwarf galaxies and the structure of their host dark-matter halos as inferred from kinematics measurements both exhibit dramatic diversity, maximized in the regime of massive dwarf galaxies. Within the standard cosmology, tentatively solutions to the small-scale issues involves considering halo-to-halo statistical variance and complicated baryonic feedback. Collisional self-interactions in the dark sector provide appealing possibilities of solving most of the small-scale issues without resorting to complicated baryonic processes. In this seminar, I aim at a comprehensive overview of the small-scale issues and discuss on-going efforts in both CDM and in SIDM.

Bio: Dr. Fangzhou Jiang is an assistant professor at the Kavli Institute for Astronomy and Astrophysics, Peking University. He obtained his PhD from Yale University in 2016, and was a PBC Fellow in the Hebrew University of Jerusalem from 2016 to 2019, a Troesh Scholar at Caltech with a jointly appointed Theory Fellow at the Carnegie Observatories from 2020 to 2022, before joining KIAA in 2023. Fangzhou carries out theoretical and computational studies of galaxies and cosmology. His research programs aim at a comprehensive theoretical picture of dark-matter halos and their interplay with inhabitant galaxies across the history of the Universe, with the ultimate goal being to constrain the properties of dark matter and to understand galaxy evolution all the way from the cosmological large scales down to sub-galactic small scales.