We investigate the relation between star formation rates and local galaxy environment for a stellar mass selected galaxy sample in the redshift range 1.5 \leq z \leq 3 .
We use near-infra-red imaging from an extremely deep Hubble Space Telescope survey , the GOODS-NICMOS Survey ( GNS ) to measure local galaxy densities based on the nearest neighbour approach , while star-formation rates are estimated from rest-frame UV-fluxes .
Due to our imaging depth we can examine galaxies down to a colour-independent stellar mass completeness limit of \log~ { } M _ { \ast } = 9.5 M _ { \odot } at z \sim 3 .
We find a strong dependence of star formation activity on galaxy stellar mass over the whole redshift range , which does not depend on local environment .
The average star formation rates are largely independent of local environment apart from in the highest relative over-densities .
Galaxies in over-densities of a factor of > 5 have on average lower star formation rates by a factor of 2 - 3 , but only up to redshifts of z \sim 2 .
We do not see any evidence for AGN activity influencing these relations .
We also investigate the influence of the very local environment on star-formation activity by counting neighbours within 30 kpc radius .
This shows that galaxies with two or more close neighbours have on average significantly lower star formation rates as well as lower specific star formation rates up to z \sim 2.5 .
We suggest that this might be due to star formation quenching induced by galaxy merging processes .