Galaxy Properties in Different Environments at z> 1.5 in the GOODS-NICMOS Survey

Abstract

We present a study of the relationship between galaxy colour, stellar mass, and local galaxy density in a deep near-infrared imaging survey up to a redshift of z ∼ 3 using the GOODS NICMOS Survey (GNS). The GNS is a very deep, near-infrared Hubble Space Telescope survey imaging a total of 45 arcmin² in the GOODS fields, reaching a stellar mass completeness limit of M _∗ = 10^9. 5 M _⊙ at z = 3. Using this data we measure galaxy local densities based on galaxy counts within a fixed aperture, as well as the distance to the third, fifth and seventh nearest neighbour. We find a strong correlation between colour and stellar mass at all redshifts up to z ∼ 3. We do not find a strong correlation between colour and local density, however, the highest overdensities might be populated by a higher fraction of blue galaxies than average or underdense areas, indicating a possible reversal of the colour-density relation at high redshift. Our data suggests that the possible higher blue fraction at extreme overdensities might be due to a lack of massive red galaxies at the highest local densities.