Individual Alpha Elements, C, N, and Ba in Early Type Galaxies

TL;DR

This study analyzes spectral data from early type galaxies to determine detailed chemical abundances, revealing trends in alpha elements and other elements relative to galaxy mass, with implications for nucleosynthesis sources.

Contribution

It provides detailed abundance measurements for multiple elements in early type galaxies and examines their trends with galaxy velocity dispersion, expanding understanding of galactic chemical evolution.

Findings

Larger galaxies show higher alpha/iron ratios, especially for O and Si.

Ca and Ti do not follow the alpha trend, indicating different nucleosynthetic origins.

C, N, and Ba also increase with galaxy mass, suggesting contributions from intermediate-mass stars.

Abstract

Spectral data on early type galaxies is analyzed for chemical abundance with an emphasis on obtaining detailed abundances for the elements O and Si in addition to C, N, Na, Mg, Ca, Fe, and Ba. The abundance trends with velocity dispersion fit preconceptions based upon previous Mg conclusions, namely that larger galaxies have a higher alpha element to iron peak ratio indicative of a higher ratio of Type II to Type Ia supernova products. The heaviest alpha elements, Ca and Ti, do not participate in this trend, although this fact does not necessarily alter the basic picture given the uncertainties in nucleosynthetic yields. Elements that likely have significant contributions from intermediate-mass stars, namely C, N, and Ba, also gain ground relative to Fe in massive galaxies at a modest level, with the Ba conclusion uncertain from our data alone.