We present a study of the [OIII]λ5007 line profile in a
sub-sample of 8 active galactic nuclei (AGN) and 6 non-AGN in the
optically-selected green valley at z<0.5 using long-slit
spectroscopic observations with the 11 m Southern African Large Telescope.
Gaussian decomposition of the line profile was performed to study its different
components. We observe that the AGN profile is more complex than the non-AGN
one. In particular, in most AGN (5/8) we detect a blue wing of the line. We
derive the FWHM velocities of the wing and systemic component, and find that
AGN show higher FWHM velocity than non-AGN in their core component. We also
find that the AGN show blue wings with a median velocity width of approximately
600 kms−1, and a velocity offset from the core component in the
range -90 to -350 kms−1, in contrast to the non-AGN galaxies, where
we do not detect blue wings in any of their [OIII]λ5007 line
profiles. Using spatial information in our spectra, we show that at least three
of the outflow candidate galaxies have centrally driven gas outflows extending
across the whole galaxy. Moreover, these are also the galaxies which are
located on the main sequence of star formation, raising the possibility that
the AGN in our sample are influencing SF of their host galaxies (such as
positive feedback). This is in agreement with our previous work where we
studied SF, morphology, and stellar population properties of a sample of green
valley AGN and non-AGN galaxies.Comment: 15 pages, 6 figures, accepted for publication in Ap