A Unified Model for the Coevolution of Galaxies and Their Circumgalactic Medium: The Relative Roles of Turbulence and Atomic Cooling Physics

Abstract

The circumgalactic medium (CGM) plays a pivotal role in regulating gas flows around galaxies and thus shapes their evolution. However, the details of how galaxies and their CGM coevolve remain poorly understood. We present a new time-dependent two-zone model that self-consistently tracks not just mass and metal flows between galaxies and their CGM but also the evolution of the global thermal and turbulent kinetic energy of the CGM. Our model accounts for heating and turbulence driven by both supernova winds and cosmic accretion as well as radiative cooling, turbulence dissipation, and halo outflows due to CGM overpressurization. We demonstrate that, depending on parameters, the CGM can undergo a phase transition (“thermalization”) from a cool, turbulence-supported phase to a virial-temperature, thermally supported phase. This CGM phase transition is largely determined by the ability of radiative cooling to balance heating from supernova winds and turbulence dissipation. We perform an initial calibration of our model to the FIRE-2 cosmological hydrodynamical simulations and show that it can approximately reproduce the baryon cycles of the simulated halos. In particular, we find that, for these parameters, the phase transition occurs at high redshift in ultrafaint progenitors and at low redshift in classical M vir ∼ 1011 M ⊙ dwarfs, while Milky Way–mass halos undergo the transition at z ≈ 0.5. We see a similar transition in the simulations though it is more gradual, likely reflecting radial dependence and multiphase gas not captured by our model. We discuss these and other limitations of the model and possible future extensions.

The Structure and Composition of Multiphase Galactic Winds in a Large Magellanic Cloud Mass Simulated Galaxy

“…A potential concern is that while the generally low mass loading factor of our simulation seems to be consistent with recent observations (e.g., McQuinn et al 2019;Marasco et al 2023) and requirements of recent "regulator models" for galaxy formation (e.g., Pandya et al 2023;Carr et al 2023), our values for the energy loading seem to be too low by roughly 1 order of magnitude. Steinwandel et al (2023) argued that some of this effect could be reconciled by the inclusion of runaway stars, which have not been included in our present modeling.…”

Geometry, Dissipation, Cooling, and the Dynamical Evolution of Wind-blown Bubbles

“…Feedback plays multiple roles on multiple scales. AGNs and "superbubble" feedback from repeated supernovae (SNe) drive outflows from galaxies overall (Tomisaka & Ikeuchi 1986;McCray & Kafatos 1987;Mac Low & McCray 1988;Koo & McKee 1992;Faucher-Giguère & Quataert 2012;Cicone et al 2014;Sharma et al 2014;King & Pounds 2015;Gentry et al 2017Gentry et al , 2019Yadav et al 2017;El-Badry et al 2019;Orr et al 2022), set the energy and mass-and metal-loading of galactic winds Kim et al 2020aKim et al , 2020bPandya et al 2020;Schneider et al 2020;Fielding & Bryan 2022;Smith et al 2024), and regulate the energy balance of the galaxy's circumgalactic medium (Fielding et al 2017;Faucher-Giguère & Oh 2023;Pandya et al 2023). Expanding remnants from individual and clustered SNe are also believed to bear primary responsibility for driving turbulence on large scales in the interstellar medium (ISM; McKee & Ostriker 1977;Elmegreen & Scalo 2004;Agertz et al 2009;Kim et al 2011;Ostriker & Shetty 2011;Hennebelle & Iffrig 2014;Girichidis et al 2016;Ostriker & Kim 2022).…”