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tokens: Joung Mac Low ( 2006 ), we assign 20% of the explosions to SN Ia and 80% to SN II with scale heights of and , respectively (Tammann et al. 1994 ). However, estimates of the displacement of runaway OB stars suggests that the effective scale height of SNe II might be larger (Li et al. 2015 ). We separately vary the thermal energy injection per SN, , and the CR energy injection, , with . We discuss three different simulations: purely thermal SNe (, TH1-CR0 ), purely CR SNe (, TH0-CR1 ), and the physically most realistic setup with both energy injections (, TH1-CR1 ). 3. MORPHOLOGICAL EVOLUTION In all simulations, the SNe induce the formation of filaments, clumps, and voids. The presence of CRs leads to a smoother morphological appearance. An overview of the disk structure after is depicted in Figure 1 with cuts through the center of the box for the density edge-on (top) and face-on (middle) and the CR energy density (bottom). From left to right, we present TH1-CR0 , TH0-CR1, and TH1-CR1 . Both runs with CRs quickly push gas away from the midplane and form an extended atmosphere, whereas in the simulation with only thermal SN feedback, the disk remains compact without a noticeable extended layer of gas above the disk. The CR energy density shows relatively small spatial variations of about one order of magnitude. High CR energy peaks correspond to recent SNe and disappear quickly due to diffusion. Figure 1. Structure of the disk after of evolution. The left panel shows the run without CRs, the middle panel the run with purely CR feedback, and the right panel the simulation with both feedback energies. In the top and middle row, we plot the density edge-on and face-on in cuts through the center of the box. The bottom row depicts the CR energy density in the midplane. The disk in the run including CRs is significantly thicker compared to the purely thermal run. The thermal energy input of the SNe is primarily important in the denser part of the disk. CRs show their main impact in generating an extended atmosphere. The CR energy density is smooth in the midplane. Local variations are due to recent SNe and the resulting CR injection. Those variations disappear after less than a Myr due to diffusion. In Figure 2 , we show the vertical profile of the density for all simulations at . The arrows indicate the heights of 90% enclosed mass. The inclusion of CRs increases from to with similar values for both runs including CRs. The additional thermal energy injection from SNe in run TH1-CR1 changes the profile up to a height of . At larger altitudes, the profiles for TH0-CR1 and TH1-CR1 are basically indistinguishable. For comparison, we include the vertical density profile of the MW (Dickey Lockman 1990 ) showing reasonable agreement with both CR runs. Figure 2. Vertical profiles of the total gas density for all simulations. The arrows indicate the height of 90% enclosed mass. A fit to the observed density profile of the solar neighborhood (Dickey Lockman