Galaxy properties in different environments up to z∼ 3 in the GOODS NICMOS Survey.

We study the relationship between galaxy colour, stellar mass and local galaxy density in a deep near-infrared imaging survey up to a redshift of using the GOODS (Great Observatories Origins Deep Survey) NICMOS (Near Infrared Camera and Multi-Object Spectrometer) Survey (GNS). The GNS is a deep near-infrared Hubble Space Telescope survey imaging a total of 45 arcmin of the GOODS fields, reaching a stellar mass completeness limit of at . Using these 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 compare the average rest-frame colour and fraction of blue galaxies in different local densities and at different stellar masses. We find a strong correlation between colour and stellar mass at all redshifts up to . Massive red galaxies are already in place at at the expected location of the red sequence in the colour-magnitude diagram, although they are star forming. We do not find a strong correlation between colour and local density; however, there may be evidence that the highest overdensities are populated by a higher fraction of blue galaxies than average or underdense areas. This could be indicating that the colour-density relation at high redshift is reversed with respect to lower redshifts (), where higher densities are found to have lower blue fractions. Our data suggest that the possible higher blue fraction at extreme overdensities might be due to a lack of massive red galaxies at the highest local densities. [ABSTRACT FROM AUTHOR]