Grecco A. Oyarzún
Signatures of stellar accretion in MaNGA early-type galaxies
Oyarzún, Grecco A.; Bundy, Kevin; Westfall, Kyle B.; Belfiore, Francesco; Thomas, Daniel; Maraston, Claudia; Lian, Jianhui; Aragón-Salamanca, Alfonso; Zheng, Zheng; Gonzalez-Perez, Violeta; Law, David R.; Drory, Niv; Andrews, Brett H.
Kyle B. Westfall
David R. Law
Brett H. Andrews
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.
|Journal Article Type||Article|
|Publication Date||Aug 1, 2019|
|Publisher||American Astronomical Society|
|Peer Reviewed||Peer Reviewed|
|APA6 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), doi:10.3847/1538-4357/ab297c|
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