Stellar Abundances at the Center of Early Type Galaxies with Fine Structure

Abstract

Our understanding of early-type galaxies (ETGs) has grown in the past decade with the advance of full-spectrum fitting techniques used to infer the properties of the stellar populations that make-up the galaxy. We present ages, central velocity dispersions, and abundance ratios relative to Fe of C, N, O, Mg, Si, Ca, Ti, Cr, Mn, Co, Ni, Cu, Sr, Ba, and Eu, derived using full-spectrum fitting techniques for three ETGs NGC 2865, NGC 3818, and NGC 4915. Each of these three galaxies were selected because they have optical, disturbed structures (fine structure) that are linked to major merger events that occurred 1, 7, and 6 Gyr ago, respectively. Two of the ETGs, NGC 3818 and NGC 4915, show chemical signatures similar to ETGs without fine structure, which is consistent with a gas-poor merger of elliptical galaxies in which substantial star formation is not expected. For NGC 2865, we find a statistically higher abundance of Ca (an $\alpha$-element) and Cr and Mn (Fe-peak elements). We show that for NGC 2865, a simple gas-rich merger scenario fails to explain the larger abundance ratios compared to ETGs without fine structure. These three early-type galaxies with fine structure exhibit a range of abundances, suggesting ETGs with fine structure can form via multiple pathways and types of galaxy mergers.

arXiv comment26 pages, 8 figures

References in corpus (51)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• On the variation of the Initial Mass Function
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Gasdynamics and Starbursts in Major Mergers
• The epochs of early-type galaxy formation as a function of environment
• First results from the IllustrisTNG simulations: A tale of two elements -- chemical evolution of magnesium and europium
• The Atlas3D project -- I. A volume-limited sample of 260 nearby early-type galaxies: science goals and selection criteria
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• Minor mergers and the size evolution of elliptical galaxies
• Galactic Chemical Evolution: Hydrogen Through Zinc
• Galactic chemical evolution: Carbon through Zinc
• The Two Phases of Galaxy Formation
• De Re Metallica: The cosmic chemical evolution of galaxies
• Optimal Techniques in Two-dimensional Spectroscopy: Background Subtraction for the 21st Century
• The SAURON project. I. The panoramic integral-field spectrograph
• The SAURON project. II. Sample and early results
• The MaNGA Integral Field Unit Fiber Feed System for the Sloan 2.5 m Telescope
• Optimization of Starburst99 for Intermediate-Age and Old Stellar Populations
• The Stellar Initial Mass Function in Early-Type Galaxies From Absorption Line Spectroscopy. II. Results
• The Atlas3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies
• The Effects of Stellar Rotation. II. A Comprehensive Set of Starburst99 Models
• The Evolution of Isotope Ratios in the Milky Way Galaxy
• The SDSS-IV MaNGA Sample: Design, Optimization, and Usage Considerations
• SDSS-IV MaNGA IFS Galaxy Survey --- Survey Design, Execution, and Initial Data Quality
• The ATLAS${}^{3D}$ project - XXV: Two-dimensional kinematic analysis of simulated galaxies and the cosmological origin of fast and slow rotators
• Population Synthesis in the Blue IV: Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations
• A Library of Theoretical Ultraviolet Spectra of Massive, Hot Stars for Evolutionary Synthesis
• Early-Type Galaxy Archeology: Ages, Abundance Ratios, and Effective Temperatures from Full-Spectrum Fitting
• Counting Low-Mass Stars in Integrated Light
• The First Galaxies: Chemical Enrichment, Mixing, and Star Formation
• The MASSIVE Survey - I. A Volume-Limited Integral-Field Spectroscopic Study of the Most Massive Early-Type Galaxies within 108 Mpc
• Synthetic spectra of H Balmer and HeI absorption lines. II: Evolutionary synthesis models for starburst and post-starburst galaxies
• Metal-rich, Metal-poor: Updated Stellar Population Models for Old Stellar Systems
• Scaling Mass Profiles around Elliptical Galaxies Observed with Chandra and XMM-Newton
• Interacting galaxies on FIRE-2: The connection between enhanced star formation and interstellar gas content
• Spatially resolved star formation and fuelling in galaxy interactions
• The Evolution of Early-Type Galaxies in Distant Clusters I.: Surface Photometry and Structural Parameters for 53 Galaxies in the z=0.33 Cluster CL1358+62
• Stellar population gradients in early-type cluster galaxies
• The GALEX UV emission in shell galaxies: tracing galaxy "rejuvenation" episodes
• Element abundances in the stars of the MILES spectral library: the Mg/Fe ratio
• Linked evolution of gas and star formation in galaxies over cosmic history
• Nuclear stellar discs in early-type galaxies --- II. Photometric properties
• SDSS-IV MaNGA: Radial Gradients in Stellar Population Properties of Early-Type and Late-Type Galaxies
• Nearby early-type galaxies with ionized gas VI. The Spitzer-IRS view
• Radial Kinematics of Isolated Elliptical Galaxies
• Strontium and Barium In Early-Type Galaxies
• Coordinated Assembly of Brightest Cluster Galaxies
• Stellar Population and Elemental Abundance Gradients of Early-type Galaxies
• Remnants of recent mergers in nearby early-type galaxies and their classification
• Star formation in low density HI gas around the Elliptical Galaxy NGC2865