Star Formation History and Stellar Metallicity Distribution in a Cold Dark Matter Universe

We study star formation history and stellar metallicity distribution ingalaxies in a Lambda cold dark matter universe using a hydrodynamiccosmological simulation. Our model predicts star formation rate declining intime exponentially from an early epoch to the present with the time-scale of 6Gyr, which is consistent with the empirical Madau plot with modest dustobscuration. Star formation in L^* galaxies continues intermittently to thepresent also with an exponentially declining rate of a similar time-scale,whereas in small galaxies star formation ceases at an early epoch. The mean ageof the extant stars decreases only slowly with increasing redshift, and exceeds1 Gyr at z=3. Normal galaxies contain stars with a wide range of metallicityand age: stars formed at z<1 have metallicity of 0.1-1.0 Zsun, while old starstake a wide range of values from 10^{-6} Zsun to 3.0 Zsun. The mean metallicityof normal galaxies is in the range 0.1-1.0 Zsun. Dwarf galaxies that containonly old stars have a wide range of mean metallicity (10^{-4}-1.0 Zsun), but onaverage they are metal deficient compared with normal galaxies.Comment: 8 pages, 5 figures, emulateapj style. Accepted version in ApJ. More emphasis on the comparison with observation