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tokens: it rises rapidly to a peak at . Bottom: The metallicity distribution function over the entire galaxy. The bottom panel of Fig. 3 shows the metallicity distribution function (MDF) across the model. The model’s MDF peaks at nearly Solar metallicity and has a long tail to low . The MDF is similar to some extent to the MDF of the bulge (e.g. Zoccali et al. 2008 ; Gonzalez et al. 2015 ). 3 KINEMATIC FRACTIONATION Fig. 4 shows the evolution over the last (i.e. since redshift z = 0.4), of the bar amplitude, A 2 , defined as the usual m = 2 amplitude of the Fourier moment measured overall stars (e.g. Debattista Sellwood 2000 ). The bar forms quite late, starting from ( z ≃ 0.19). It reaches a peak amplitude at , and weakens somewhat in the next Gyr, as is often seen in simulations of isolated galaxies. In isolated simulations, bars generally experience renewed growth past this point (e.g. Combes Sanders 1981 ; Sellwood Moore 1999 ; Debattista Sellwood 2000 ; Athanassoula 2002 ; Bournaud Combes 2002 ; O’Neill Dubinski 2003 ; Martinez-Valpuesta et al. 2006 ), but the late bar formation in this simulation does not give the bar time to strengthen again. Figure 4. Bar amplitude evolution in m12m since redshift z = 0.4 (corresponding to of evolution). 3.1 Density separation Fig. 5 shows the mass density distribution at z = 0 in face-on and edge-on projections for the model separated by different stellar populations. As in Debattista et al. ( 2017 ), younger populations exhibit a stronger bar and a more prominent box or peanut (B/P) shape than the older ones. The difference in the B/P strength as a function of age is a signature of kinematic fractionation as discussed in Debattista et al. ( 2017 ). Figure 5. Density distributions in the face-on (top panels) and edge-on (bottom panels) projections. The bottom left panels show the full edge-on projection, while the bottom right panels show a cross-section with particles chosen within . In the top row of each set of panels we show the accreted stars (left) and all the stars (right). The rest of the panels show populations separated by time of formation of the stars, age. Fig. 5 also shows the density distribution of the stellar population that was accreted, which we define as stars that formed at radius . The accreted stars, which account for of all the stars, formed primarily () by redshift z = 1.27 (). They have a density distribution similar to that of the oldest (age now) in situ stars, i.e. those formed at (see also El-Badry et al. 2018b ). Like the oldest bin, no bar or X-shape is present in the accreted population. 3.2 Age and metallicity dependence of bar amplitude Fig. 6 shows the dependence of the usual m = 2 Fourier global bar amplitude on the age and metallicity. As also apparent from the face-on maps in Fig. 5 , the bar is stronger in younger populations than in the older ones. The very oldest populations have quite a weak bar overall, while the youngest populations have a 3.5 times stronger bar.