Year: 2019
Type: article
Abstract: The late assembly of massive galaxies is thought to be dominated by stellar accretion in their outskirts (beyond two effective radii R e) due to dry, minor galaxy mergers. We use observations of 1010 passive early-type galaxies (ETGs) within z < 0.15 from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) to search for evidence of this accretion. The outputs from the stellar population fitting codes FIREFLY, pPXF, and Prospector are compared to control systematic errors in stellar metallicity (Z) estimation. We find that the average radial log Z/Z ⊙ profiles of ETGs in various stellar mass (M *) bins are not linear. As a result, these profiles are poorly characterized by a single gradient value, explaining why weak trends reported in previous work can be difficult to interpret. Instead, we examine the full radial extent of stellar metallicity profiles and find them to flatten in the outskirts of M * ≳ 1011 M ⊙ ETGs. This is a signature of stellar accretion. Based on a toy model for stellar metallicity profiles, we infer the ex situ stellar mass fraction in ETGs as a function of M * and galactocentric radius. We find that ex situ stars at R ∼ 2R e make up 20% of the projected stellar mass of M * ≲ 1010.5 M ⊙ ETGs, rising up to 80% for M * ≳ 1011.5 M ⊙ ETGs.
Source: The Astrophysical Journal
Authors: Grecco A. Oyarzún, Kevin Bundy, Kyle B. Westfall, Francesco Belfiore, Daniel Thomas, Claudia Maraston, Jianhui Lian, Alfonso Aragón-Salamanca, Zheng Zheng, Violeta Gonzalez-Perez, David R. Law, Niv Drory, Brett H. Andrews
Institutions: University of California, Santa Cruz, University of California Observatories, European Southern Observatory, University of Portsmouth, University of Nottingham, Chinese Academy of Sciences, National Astronomical Observatories, Lancaster University, Space Telescope Science Institute, McDonald Observatory, The University of Texas at Austin, University of Pittsburgh
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: Smithsonian Institution, U.S. Department of Energy, Alfred P. Sloan Foundation, Yale University, Carnegie Institution of Washington, Vanderbilt University, Ohio State University, University of Washington, Johns Hopkins University, Carnegie Mellon University, University of Notre Dame, University of Portsmouth, New Mexico State University, York University, University of Oxford, National Natural Science Foundation of China, Consejo Nacional de Ciencia y Tecnología, Ministério da Ciência, Tecnologia e Inovação, Universidad Nacional Autónoma de México, Max-Planck-Institut für Astrophysik, Max-Planck-Institut für Astronomie, Instituto de Astrofísica de Canarias, Office of Science, University of Colorado Boulder, Smithsonian Astrophysical Observatory, Science and Technology Facilities Council, Leibniz-Gemeinschaft, Lawrence Berkeley National Laboratory
OpenAlex ID: W2949139691