Coevolution of Dwarf Galaxies and Their Circumgalactic Medium Across Cosmic Time

Abstract Dwarf galaxies (DGs) are thought of as the building blocks of large galaxies such as our Milky Way. This paper presents new high-resolution hydrodynamical simulations of DGs and their intergalactic medium with the GIZMO code. Our simulations consider the key physical processes of galaxy evolution, such as gas cooling, chemistry, and stellar and black hole feedback. Unlike previous work, the initial conditions of our simulations take DGs of 2–5 × 10 10 M ⊙ from the realistic cosmology simulations of IllustrisTNG . We further increase the original resolution of IllustrisTNG by a factor of ∼100 via a particle-splitting scheme. Our results show that the evolution of the complex multiphase circumgalactic medium (CGM) and its metal content is sensitive to the redshift of DGs. The accretion of the CGM into DGs plays a key role, providing 20%–50% of the star-forming gas and replenishing 40%–70% of the total mass in the galactic disk. Furthermore, the accretion histories of the supermassive black holes (SMBHs) at the centers of high- z DGs shows episodic patterns, with high-accreting states close to ∼10% of the Eddington mass accretion rate, implying the rapid growth of SMBHs in the early Universe, which may be revealed by coming observations from the James Webb Space Telescope.