Adding a Suite of Chemical Abundances to the MACER Code for the Evolution of Massive Elliptical Galaxies

Abstract

Abstract We add a suite of chemical abundances to the MACER (Massive AGN Controlled Ellipticals Resolved) 2D code, by solving 12 additional continuity equations for H, He, C, N, O, Ne, Mg, Si, S, Ca, Fe, and Ni with sources from AGB stars and Type Ia and II supernovae with metal yields based on standard stellar physics. New stars, formed in Toomre unstable circumnuclear disks (of a size ≲150 pc), are assumed to have a top-heavy initial mass function with a power index of 1.65. The metal dilution effects due to cosmic accretion are also included. With a high resolution of a few parsecs in central regions, resolved black hole accretion, and active galactic nucleus (AGN) feedback, we can track the metal enrichment, transportation, and dilution throughout the modeled massive elliptical galaxy of velocity dispersion ∼280 km s−1. We retrieve the chemical composition of the broad absorption line (BAL) winds launched by the central AGN, synthesize the X-ray features of the hot ISM, and find that (1) the simulated metallicity in the BAL winds could be up to ∼8 Z ⊙, while that of the hot ISM in the host galaxy is ∼2.3 Z ⊙, matching well with SDSS observations of BLR gas; (2) the X-ray emitting hot gas is metal-enriched with a typical value ∼2.5 Z ⊙; (3) the circumunuclear cold gas disk, where the metals are condensed, further enriched, and recycled, plays a critical role in the metal enrichment; (4) the black hole accretion rate linearly correlates with the star formation rate in the circumnuclear disk, i.e., , but lagged in time by roughly 106 yr.