Remnant gas energy in units of keV per proton as measured 500 Myr after the merger between two disk galaxies plotted as a function of the orbital pericentric distance R_peri divided by the original disk scale length ﹩R_{d}﹩. Open circles are the progenitor disk galaxy 5 × MW, the largest progenitor disk galaxy; filled squares are MW disks; the asterisks are Dwarf1; and the filled triangles are Dwarf2. Solid lines are fits to the data using eq. (4) and described in the text.