We investigate the star formation histories ( SFHs ) of high redshift ( 3 \lesssim z \lesssim 5 ) star-forming galaxies selected based on their rest-frame ultraviolet ( UV ) colors in the CANDELS/GOODS-S field .
By comparing the results from the spectral-energy-distribution-fitting analysis with two different assumptions about the SFHs — i.e. , exponentially declining SFHs as well as increasing ones , we conclude that the SFHs of high-redshift star-forming galaxies increase with time rather than exponentially decline .
We also examine the correlations between the star formation rates ( SFRs ) and the stellar masses .
When the galaxies are fit with rising SFRs , we find that the trend seen in the data qualitatively matches the expectations from a semi-analytic model of galaxy formation .
The mean specific SFR is shown to increase with redshift , also in agreement with the theoretical prediction .
From the derived tight correlation between stellar masses and SFRs , we derive the mean SFH of star-forming galaxies in the redshift range of 3 \leq z \leq 5 , which shows a steep power-law ( with power \alpha = 5.85 ) increase with time .
We also investigate the formation timescales and the mean stellar population ages of these star-forming galaxies .
Our analysis reveals that UV-selected star-forming galaxies have a broad range of the formation redshift .
The derived stellar masses and the stellar population ages show positive correlation in a sense that more massive galaxies are on average older , but with significant scatter .
This large scatter implies that the galaxies ’ mass is not the only factor which affects the growth or star formation of high-redshift galaxies .