Signatures of stellar accretion in MaNGA early-type galaxies

Oyarz�n, Grecco A.; Bundy, Kevin; Westfall, Kyle B.; Belfiore, Francesco; Thomas, Daniel; Maraston, Claudia; Lian, Jianhui; Arag�n-Salamanca, Alfonso; Zheng, Zheng; Gonzalez-Perez, Violeta; Law, David R.; Drory, Niv; Andrews, Brett H.

Abstract

The late assembly of massive galaxies is thought to be dominated by stellar accretion in their outskirts (beyond 2 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 SDSS IV MaNGA to search for evidence of this accretion. The outputs from the stellar population fitting codes FIREFLY, pPXF, and Prospector are compared to control for systematic errors in stellar metallicity (Z) estimation. We find that the average radial logZ/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 * 10 11 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 * 10 10.5 M ETGs, rising up to 80% for M * 10 11.5 M ETGs.

Citation

Oyarzún, G. A., Bundy, K., Westfall, K. B., Belfiore, F., Thomas, D., Maraston, C., …Andrews, B. H. (2019). Signatures of stellar accretion in MaNGA early-type galaxies. Astrophysical Journal, 880(2), Article 111. https://doi.org/10.3847/1538-4357/ab297c

• Journal Article Type: Article
• Acceptance Date: Jun 11, 2019
• Online Publication Date: Jul 31, 2019
• Publication Date: Aug 1, 2019
• Deposit Date: Jun 18, 2019
• Publicly Available Date: Jun 18, 2019
• Journal: The Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 880
• Issue: 2
• Article Number: 111
• DOI: https://doi.org/10.3847/1538-4357/ab297c
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://nottingham-repository.worktribe.com/output/2203722
• Publisher URL: https://iopscience.iop.org/article/10.3847/1538-4357/ab297c
• Additional Information: Journal title: The Astrophysical Journal; Article type: paper; Article title: Signatures of Stellar Accretion in MaNGA Early-type Galaxies; Copyright information: © 2019. The American Astronomical Society. All rights reserved.; Date received: 2018-11-21; Date accepted: 2019-06-11; Online publication date: 2019-07-31