Stellar Populations in Gas‐rich Galaxy Mergers. II. Feedback Effects of Type Ia and Type II Supernovae

We numerically investigate chemodynamical evolution of major disk-disk galaxymergers in order to explore the origin of mass-dependent chemical, photometric,and spectroscopic properties observed in elliptical galaxies. We particularlyinvestigate the dependence of the fundamental properties on merger progenitordisk mass (M_d). Main results obtained in this study are the following three.(1) More massive (luminous) ellipticals formed by galaxy mergers between moremassive spirals have larger metallicity (Z) and thus show redder colors: Thetypical metallicity ranges from ~ 1.0 solar abundance (Z~ 0.02) for ellipticalsformed by mergers with M_d = 10^10 M_solar to ~ 2.0 solar (Z ~ 0.04) for thosewith M_d = 10^12 M_solar. (2) The absolute magnitude of negative metallicitygradients developed in galaxy mergers is more likely to be larger for massiveellipticals. Absolute magnitude of metallicity gradient correlates with that of agegradient in ellipticals in the sense that an elliptical with steeper negativemetallicity gradient is more likely to show steeper age gradient. (3) BothM/L_B and M/L_K, where M, L_B, and L_K are total stellar mass of galaxymergers, B-band luminosity, and K-band one, respectively, depend on galacticmass in such a way that more massive ellipticals have larger M/L_B and smallerM/L_K.Comment: 58 pages 16 figures, ApJ in press (March 1999 issue