Galaxy And Mass Assembly (GAMA): The environmental dependence of the
  galaxy main sequence
  Aims. We aim to investigate if the environment (characterised by the host
dark matter halo mass) plays any role in shaping the galaxy star formation main
sequence (MS).
  Methods. The Galaxy and Mass Assembly project (GAMA) combines a spectroscopic
survey with photometric information in 21 bands from the far-ultraviolet (FUV)
to the far-infrared (FIR). Stellar masses and dust-corrected star-formation
rates (SFR) are derived from spectral energy distribution (SED) modelling using
MAGPHYS. We use the GAMA galaxy group catalogue to examine the variation of the
fraction of star-forming galaxies (SFG) and properties of the MS with respect
to the environment.
  Results. We examine the environmental dependence for stellar mass selected
samples without preselecting star-forming galaxies and study any dependence on
the host halo mass separately for centrals and satellites out to z ~ 0.3. We
find the SFR distribution at fixed stellar mass can be described by the
combination of two Gaussians (referred to as the star-forming Gaussian and the
quiescent Gaussian). Using the observed bimodality to define SFG, we
investigate how the fraction of SFG F(SFG) and properties of the MS change with
environment. For centrals, the position of the MS is similar to the field but
with a larger scatter. No significant dependence on halo mass is observed. For
satellites, the position of the MS is almost always lower (by ~0.2 dex)
compared to the field and the width is almost always larger. F(SFG) is similar
between centrals (in different halo mass bins) and field galaxies. However, for
satellites F(SFG) decreases with increasing halo mass and this dependence is
stronger towards lower redshift.
