We numerically investigate chemodynamical evolution of major disk-disk galaxy mergers in order to explore the origin of mass-dependent chemical , photometric , and spectroscopic properties observed in elliptical galaxies .
We particularly investigate the dependence of the fundamental properties on merger progenitor disk mass ( M _ { d } ) .
Main results obtained in this study are the following five .

( 1 ) More massive ( luminous ) ellipticals formed by galaxy mergers between more massive spirals have larger metallicity ( Z ) and thus show redder colors : The typical metallicity ranges from \sim 1.0 solar abundance ( Z \sim 0.02 ) for ellipticals formed by mergers with M _ { d } = 10 ^ { 10 } M _ { \odot } to \sim 2.0 solar ( Z \sim 0.04 ) for those with M _ { d } = 10 ^ { 12 } M _ { \odot } .

( 2 ) The absolute magnitude of negative metallicity gradients developed in galaxy mergers is more likely to be larger for massive ellipticals .
Absolute magnitude of metallicity gradient correlates with that of age gradient in ellipticals in the sense that an elliptical with steeper negative metallicity gradient is more likely to show steeper age gradient .

( 3 ) Radial color gradient is more likely to be larger for more massive ellipticals , which reflects that the metallicity gradient is larger for more massive ellipticals .
For example , typical U - R color gradient ( \Delta U - R / \Delta \log R ) for 0.1 \leq R / R _ { e } \leq 1.0 is -0.13 for ellipticals with M _ { d } = 10 ^ { 12 } M _ { \odot } and -0.07 for those with M _ { d } = 10 ^ { 10 } M _ { \odot } .

( 4 ) Both Mg _ { 2 } line index in the central part of ellipticals ( R \leq 0.1 R _ { e } ) and radial gradient of Mg _ { 2 } ( \Delta Mg _ { 2 } / \it \Delta \log R ) are more likely to be larger for massive ellipticals . \Delta Mg _ { 2 } / \it \Delta \log R correlates reasonably well with the central Mg _ { 2 } in ellipticals .
For most of the present merger models , ellipticals show positive radial gradient of H _ { \beta } line index .

( 5 ) Both M / L _ { B } and M / L _ { K } , where M , L _ { B } , and L _ { K } are total stellar mass of galaxy mergers , B -band luminosity , and K -band one , respectively , depend on galactic mass in such a way that more massive ellipticals have larger M / L _ { B } and smaller M / L _ { K } .

The essential reason for the derived mass-dependent chemical , photometric , and spectroscopic properties of ellipticals is that galactic mass can largely determine total amount of metal-enriched interstellar gas , star formation histories of galaxy mergers , and the effectiveness of Type Ia and II supernova feedback , all of which greatly affect chemodynamical evolution of galaxy mergers .