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Fig. 8

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First row: vertical mass density as a function of height (absolute value) above the disk plane, ρ(|z|), for stars in the “solar” vicinity binned in six different groups by age (left), [O/Fe] (middle), and [Fe/H] (right). The corresponding bin values are shown to the right of the figure. The color-coded values, h, indicate single exponential fits shown by the dotted lines. Two exponentials (dashed black lines) are fit to the total density in the left panel with filled circles indicating simulated data and solid line the fit. An abrupt increase in scale-height for the oldest/highest [O/Fe]/most metal-poor two samples can be seen, indicating the end of the merger-dominated early epoch. Second row: same as above, but for the vertical velocity dispersion, σz(|z|). Very similar increasing trends are seen for young stars, high [O/Fe], and metal-rich bins. As populations age, relations flatten. The black solid line is the total sample.

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