Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way’s quiescent merger history and in-situ bulge Fragkoudi, F. Blázquez-Calero, Guillermo Pérez Martín, María Isabel Methods: numerical Galaxy: bulge Galaxy: evolution Galaxies: formation Galaxies: kinematics and dynamics FF thanks Wilma Trick, Paola Di Matteo, Dimitri Gadotti, and Misha Haywood for comments on earlier versions of themanuscript which greatly improved its clarity, and for many interesting discussions. The authors thank the anonymous referee for a constructive report. The authors thank David Campbell and Adrian Jenkins for generating the initial conditions and selecting the sample of the Auriga galaxies, and Paola Di Matteo for the isolated Nbody simulations used in Appendix B. FM acknowledges support through the Program 'Rita Levi Montalcini' of the Italian MIUR. IG acknowledges financial support from CONICYT Programa Astronomia, Fondo ALMA-CONICYT 2017 31170048. AM acknowledges support from CONICYT FONDECYT Regular grant 1181797. FAG acknowledges financial support from CONICYT through the project FONDECYT Regular Nr. 1181264. FAG, AM, and IG acknowledge funding from the Max Planck Society through a Partner Group grant. This project was developed in part at the 2019 Santa Barbara Gaia Sprint, hosted by the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara. This research was supported in part at KITP by the Heising-Simons Foundation and the National Science Foundation under Grant No. NSF PHY-1748958. We explore the chemodynamical properties of a sample of barred galaxies in the Auriga magnetohydrodynamical cosmological zoom-in simulations, which form boxy/peanut (b/p) bulges, and compare these to the Milky Way (MW). We show that the Auriga galaxies which best reproduce the chemodynamical properties of stellar populations in the MW bulge have quiescent merger histories since redshift z ∼ 3.5: their last major merger occurs at tlookback>12Gyr⁠, while subsequent mergers have a stellar mass ratio of ≤1:20, suggesting an upper limit of a few per cent for the mass ratio of the recently proposed Gaia Sausage/Enceladus merger. These Auriga MW-analogues have a negligible fraction of ex-situ stars in the b/p region (⁠<1 per cent⁠), with flattened, thick disc-like metal-poor stellar populations. The average fraction of ex-situ stars in the central regions of all Auriga galaxies with b/p’s is 3 per cent – significantly lower than in those which do not host a b/p or a bar. While the central regions of these barred galaxies contain the oldest populations, they also have stars younger than 5 Gyr (>30 per cent) and exhibit X-shaped age and abundance distributions. Examining the discs in our sample, we find that in some cases a star-forming ring forms around the bar, which alters the metallicity of the inner regions of the galaxy. Further out in the disc, bar-induced resonances lead to metal-rich ridges in the Vϕ − r plane – the longest of which is due to the Outer Lindblad Resonance. Our results suggest the Milky Way has an uncommonly quiet merger history, which leads to an essentially in-situ bulge, and highlight the significant effects the bar can have on the surrounding disc. 2021-03-15T08:42:19Z 2021-03-15T08:42:19Z 2020-04-21 info:eu-repo/semantics/article Publisher version: F Fragkoudi, R J J Grand, R Pakmor, G Blázquez-Calero, I Gargiulo, F Gomez, F Marinacci, A Monachesi, M K Ness, I Perez, P Tissera, S D M White, Chemodynamics of barred galaxies in cosmological simulations: On the Milky Way’s quiescent merger history and in-situ bulge, Monthly Notices of the Royal Astronomical Society, Volume 494, Issue 4, June 2020, Pages 5936–5960, [https://doi.org/10.1093/mnras/staa1104] http://hdl.handle.net/10481/67203 10.1093/mnras/staa1104 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ info:eu-repo/semantics/openAccess Atribución-NoComercial-SinDerivadas 3.0 España Oxford University Press