Composite Stellar Populations and Element by Element Abundances in the Milky Way Bulge and Elliptical Galaxies

Abstract

This paper explores the integrated-light characteristics of the Milky Way (MW) bulge and to what extent they match those of elliptical galaxies in the local universe. We model composite stellar populations with realistic abundance distribution functions (ADFs), tracking the trends of individual elements as a function of overall heavy element abundance as actually observed in MW bulge stars. The resultant predictions for absorption feature strengths from the MW bulge mimic elliptical galaxies better than solar neighborhood stars do, but the MW bulge does not match elliptical galaxies, either. Comparing bulge versus elliptical galaxies, Fe, Ti, and Mg trend about the same for both but C, Na, and Ca seem irreconcilably different. Exploring the behavior of abundance compositeness leads to the concepts of "red lean" where a narrower ADF appears more metal rich than a wide one, and "red spread" where the spectral difference between wide and narrow ADFs increases as the ADF peak is moved to more metal-rich values. Tests on the systematics of recovering abundance, abundance pattern, and age from composite stellar populations using single stellar population models were performed. The chemical abundance pattern was recovered adequately, though a few minor systematic effects were uncovered. The prospects of measuring the width of the ADF of an old stellar population were investigated and seem bright using UV to IR photometry.

13 pages, 7 figures, MNRAS accepted

References in corpus (12)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Galactic chemical evolution: Carbon through Zinc
• Scaled solar tracks and isochrones in a large region of the Z-Y plane I. From the ZAMS to the TP-AGB end for 0.15 - 2.5 Mo stars
• The ACS Nearby Galaxy Survey Treasury IX. Constraining asymptotic giant branch evolution with old metal-poor galaxies
• Chemical similarities between Galactic bulge and local thick disk red giant stars
• The SAURON project - VI. Line strength maps of 48 elliptical and lenticular galaxies
• Stellar Population and Kinematic Profiles in Spiral Bulges & Disks: Population Synthesis of Integrated Spectra
• Stellar populations of early-type galaxies in different environments I. Line-strength indices
• Ages and Abundances of Red Sequence Galaxies as a Function of LINER Emission Line Strength
• The stellar population histories of early-type galaxies. III. The Coma Cluster
• The First Detailed Abundances for M giants in the inner Bulge from Infrared Spectroscopy
• Detailed AGB evolutionary models and near infrared colours of intermediate-age stellar populations: Tests on star clusters

Cited by in corpus (2)

• Two Groups of Red Giants with Distinct Chemical Abundances in the Bulge Globular Cluster NGC 6553 Through the Eyes of APOGEE
• Colors of Ellipticals from GALEX to Spitzer