Title: The Bright and Dark Sides of Massive Galaxies from the Hyper Suprime-Cam Survey

Abstract: Massive galaxies are valuable targets for studying cosmology and galaxy-halo connection as they help us locate massive dark matter halos across the history of the universe. Although the general behavior of stellar-halo mass relation (SHMR) is reasonably constrained at low-redshift, there is still much to learn about the connection between the assembly of massive galaxies to the growth of their host dark matter halos. Using deep images from the Hyper Suprime-Cam (HSC) survey and taking advantage of its unprecedented weak lensing capabilities, we reveal a remarkably tight connection between the stellar mass distribution of massive central galaxies and their host dark matter halo mass. Massive galaxies with more extended stellar mass distributions tend to live in more massive dark matter haloes. We explain this connection with a phenomenological model, showing that halo mass varies significantly at fixed total stellar mass (as much as 0.4 dex) with a clear dependence on stellar mass within 10 kpc. This two-parameter model provides a more accurate picture of the galaxy–halo connection at the high-mass end than the simple SHMR and opens a new window to connect the assembly history of halos with those of central galaxies. I will also discuss potential applications of our model on topics from the assembly of massive galaxies to cosmology using massive clusters.