Adding a Suite of Chemical Abundances to the MACER Code for the Evolution of Massive Elliptical Galaxies (original) (raw)

2019, The Astrophysical Journal

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 respectively with sources from AGB stars and supernovae of type Ia and II with metal yields based on standard stellar physics. New stars, formed in Toomre unstable circumnuclear disks (of a size 150 parsec), 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 the high resolution of few parsecs in central regions, resolved black hole accretion and AGN feedback, we can track the metal enrichment, transportation and dilution throughout the modeled massive elliptical galaxy of velocity dispersion ∼ 280 km/s. We retrieve the chemical composition of the 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 ∼ 8Z , while that of the hot ISM in the host galaxy is ∼ 2.3Z , matching well with SDSS observations of BLR gas; (2) the X-ray emitting hot gas is metal enriched with a typical value ∼ 2.5Z ; (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 ratė M BH linearly correlates with the star formation rateṀ + in the circumnuclear disk, i.e,Ṁ + ∼ 7.7Ṁ BH , but lagged in time by roughly 10 6 years.