We present a deep [ OII ] emission line survey of faint galaxies ( 22.5 < K _ { AB } < 24 ) in the Chandra Deep Field South and the FIRES field .
With these data we measure the star formation rate ( SFR ) in galaxies in the stellar mass range 8.85 \lesssim~ { } \log { ( M _ { \ast } / { M _ { \odot } } ) } ~ { } \lesssim 9.5 at 0.62 < z < 0.885 , to a limit of SFR \sim 0.1 { M _ { \odot } } yr ^ { -1 } .
The presence of a massive cluster ( MS1054-03 ) in the FIRES field , and of significant large scale structure in the CDFS field , allows us to study the environmental dependence of SFRs amongst this population of low-mass galaxies .
Comparing our results with more massive galaxies at this epoch , with our previous survey ( ROLES ) at the higher redshift z \sim 1 , and with SDSS Stripe 82 data , we find no significant evolution of the stellar mass function of star–forming galaxies between z = 0 and z \sim 1 , and no evidence that its shape depends on environment .
The correlation between specific star formation rate ( sSFR ) and stellar mass at z \sim 0.75 has a power-law slope of \beta \sim - 0.2 , with evidence for a steeper relation at the lowest masses .
The normalization of this correlation lies as expected between that corresponding to z \sim 1 and the present day .
The global SFR density is consistent with an evolution of the form ( 1 + z ) ^ { 2 } over 0 < z < 1 , with no evidence for a dependence on stellar mass .
The sSFR of these star–forming galaxies at z \sim 0.75 does not depend upon the density of their local environment .
Considering just high-density environments , the low-mass end of the sSFR- M _ { \ast } relation in our data is steeper than that in Stripe 82 at z = 0 , and shallower than that measured by ROLES at z = 1 .
Evolution of low-mass galaxies in dense environments appears to be more rapid than in the general field .