The Type Ia Supernova and Asymptotic Giant Branch Stellar Ejecta-regulated Interstellar Medium of Massive Galaxies

TL;DR

This study uses 3D hydrodynamic simulations to explore how Type Ia supernovae and AGB star ejecta regulate the interstellar medium in massive galaxies, revealing two steady states influenced by CGM pressure and heating-cooling balance.

Contribution

It provides the first detailed simulation-based analysis of the combined effects of SNIa and AGB winds on the ISM, emphasizing the importance of resolving SNIa remnants.

Findings

SNIa heating can drive a slow outflow or cause a cooling flow depending on the heating-to-cooling ratio.

The ISM properties are strongly influenced by the CGM entropy, affecting black hole accretion rates.

Approximate SNIa heating models are inadequate; resolving SNIa remnants is crucial.

Abstract

Observations and theory suggest that Type Ia supernovae (SNIa) heating and mass loss from asymptotic giant branch (AGB) stars play a crucial role in the interstellar medium (ISM) of massive galaxies. We perform 3D hydrodynamic simulations of the central few kiloparsecs of massive galaxies, including radiative cooling and mass and energy injection from AGB winds and SNIa (resolving each SNIa remnant, a few $\times10~\mathrm{pc}$ in size), excluding black hole feedback. We study systems with different initial core thermodynamic profiles, focusing on NGC 1399. Our simulations reproduce its observed density and entropy profiles well. Over $100~\mathrm{Myr}$, two steady-state profiles emerge, depending on the inner circumgalactic medium (CGM) pressure and the ratio of Ia heating to cooling: (i) if SNIa heating is less than cooling, a cooling flow develops; (ii) if SNIa heating is comparable to or exceeds cooling, SNIa heating drives a slow subsonic outflow of AGB ejecta, with black hole accretion at small radii. This outflow, pressure-confined by the CGM, adapts the ISM to the CGM properties: a low entropy CGM results in a dense, low entropy ISM with higher black hole accretion, while a high entropy CGM leads to a less dense, high entropy ISM with lower accretion. This suggests that the AGB-SNIa regulated ISM connects CGM and galaxy scales, potentially influencing black hole feedback in massive halos. Approximate methods of modeling Ia heating, such as clustered SNIa and smoothly distributed heating, produce unrealistic ISM profiles over $100~\mathrm{Myr}$, highlighting the importance of resolving SNIa in simulations.