We present a measurement of the evolution of the stellar mass function ( MF ) of galaxies and the evolution of the total stellar mass density at 0 < z < 5 , extending previous measurements to higher redshift and fainter magnitudes ( and lower masses ) .
We use deep multicolor data in the Fors Deep Field ( FDF ; I -selected reaching I _ { AB } \sim 26.8 ) and the GOODS-S/CDFS region ( K -selected reaching K _ { AB } \sim 25.4 ) to estimate stellar masses based on fits to composite stellar population models for 5557 and 3367 sources , respectively .
The MF of objects from the K -selected GOODS-S sample is very similar to that of the I -selected FDF down to the completeness limit of the GOODS-S sample .
Near-IR selected surveys hence detect the more massive objects of the same principal population as do I -selected surveys .
We find that the most massive galaxies harbor the oldest stellar populations at all redshifts .
At low z , our MF follows the local MF very well , extending the local MF down by a decade to 10 ^ { 8 } \mathrm { M _ { \odot } } .
Furthermore , the faint end slope is consistent with the local value of \alpha \sim 1.1 at least up to z \sim 1.5 .
Our MF also agrees very well with the MUNICS and K20 results at z \lesssim 2 .
The MF seems to evolve in a regular way at least up to z \sim 2 with the normalization decreasing by 50 % to z = 1 and by 70 % to z = 2 .
Objects with M > 10 ^ { 10 } \mathrm { M _ { \odot } } which are the likely progenitors of todays L > L ^ { * } galaxies are found in much smaller numbers above z \sim 2 .
However , we note that massive galaxies with M > 10 ^ { 11 } \mathrm { M _ { \odot } } are present even to the largest redshift we probe .
Beyond z \sim 2 the evolution of the mass function becomes more rapid .
We find that the total stellar mass density at z = 1 is 50 % of the local value .
At z = 2 , 25 % of the local mass density is assembled , and at z = 3 and z = 5 we find that at least 15 % and 5 % of the mass in stars is in place , respectively .
The number density of galaxies with M > 10 ^ { 11 } \mathrm { M _ { \odot } } evolves very similarly to the evolution at lower masses .
It decreases by 0.4 dex to z \sim 1 , by 0.6 dex to z \sim 2 , and by 1 dex to z \sim 4 .