SIMBA-C: an updated chemical enrichment model for galactic chemical evolution in the SIMBA simulation

Abstract

We introduce a new chemical enrichment and stellar feedback model into GIZMO, using the SIMBA sub-grid models as a base. Based on the state-of-the-art chemical evolution model of Kobayashi et al., SIMBA-C tracks 34 elements from H→Ge and removes SIMBA’s instantaneous recycling approximation. Furthermore, we make some minor improvements to SIMBA’s base feedback models. SIMBA-C provides significant improvements on key diagnostics such as the knee of the z = 0 galaxy stellar mass function, the faint end of the main sequence, and the ability to track black holes in dwarf galaxies. SIMBA-C also matches better with recent observations of the mass-metallicity relation at z = 0, 2. By not assuming instantaneous recycling, SIMBA-C provides a much better match to galactic abundance ratio measures such as [O/Fe] and [N/O]. SIMBA-C thus opens up new avenues to constrain feedback models using detailed chemical abundance measures across cosmic time.

ELUCID. VIII. Simulating the Coma Galaxy Cluster to Calibrate Model and Understand Feedback

“…Although the newer SIMBA-C (Hough et al 2023) adopts the advanced Kobayashi chemical model to track 34 different elements, we stick to the original chemical enrichment model in SIMBA, which tracks 11 elements (H, He, C, N, O, Ne, Mg, Si, S, Ca, Fe) from Type II supernovae (SN II), Type Ia supernovae (SN Ia), and asymptotic giant branch (AGB) stars, as described in Oppenheimer & Davé (2006). Yield tables for SN II from Nomoto et al (2006), for SN Ia from Iwamoto et al (1999) with 1.4M e of metals per supernova (SN), and for AGB from Oppenheimer & Davé (2006), are adopted in the simulation (assuming a helium fraction of 36%; and a Chabrier 2003 IMF).…”