An early dark matter-dominated phase in the assembly history of Milky Way-mass galaxies suggested by the TNG50 simulation and JWST observations

Whereas well-studied galaxies at cosmic noon are found to be baryon-dominated within the effective radius, recent JWST observations of z∼6-7 galaxies with stellar masses of only M_*∼10^8-9 M_⊙ surprisingly indicate that they are dark matter-dominated within r_ e≈ 1kpc. Here, we place these high-redshift measurements in the context of the TNG50 galaxy formation simulation, by measuring the central (within 1kpc) stellar, gas, and dark matter masses of galaxies in the simulation. The central baryon fraction varies strongly with galaxy stellar mass in TNG50, and this M_*-dependence is remarkably constant across 0更多