http://arxiv.org/abs/1801.01919
We study the global and radial stellar mass assembly of eight field MW-sized galaxies simulated by means of zoom-in Hydrodynamics simulations. The disk-dominated galaxies (four) show a fast initial stellar mass growth in the innermost parts, driven mostly by in-situ SF, but since $z\sim2-1$ the SF enters in a long-term quenching phase. The outer regions follow this trend but more gentle as more external they are. As the result, the radial stellar mass growth is highly inside-out due to both the inside-out structural growth and the inside-out SF quenching. The evolution of the half-mass radius is fast; for instance, $R_{0.5}$($z=1$)$<0.5$$R_{0.5}$($z=0$). Two other runs resemble lenticular galaxies. One shows also a pronounced inside-out growth and the other one presents nearly similar radial mass growth histories (MGHs). The other two galaxies suffered late major mergers. Their radial MGHs are nearly homogeneous with periods of outside-in assembly during or after the mergers. For all the simulations, the archaeological MGHs calculated from the $z=0$ stellar-particles age distribution are similar to the current MGHs, which evidences that the mass assembly by ex-situ stars and the radial mass transport do not change dramatically their radial mass distribution. Our results agree qualitatively with observational inferences from the fossil record method applied to a survey of local galaxies and from look-back observations of progenitors of MW-sized galaxies. However, the inside-out growth mode is more pronounced and the $R_{0.5}$ growth is faster in simulations than in observations. We pose the question whether other simulations find also this potential problem.
V. Avila-Reese, A. Gonzalez-Samaniego, P. Colin, et. al.
Tue, 9 Jan 18
39/94
Comments: 23 pages, 15 figures, Re-submitted to ApJ after 1st referee report
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