AGN and Star-Formation Properties of Inside-out Assembled Galaxy
  Candidates at z<0.1
  We study a sample of 48127 galaxies selected from the SDSS MPA-JHU catalogue,
with $\log M_{\star}/M_{\odot} = 10.73 - 11.03$ and $z<0.1$. Local galaxies in
this stellar mass range have been shown to have systematically shorter assembly
times within their inner regions ($<0.5~R_{50}$) when compared to that of the
galaxy as a whole, contrary to lower or higher mass galaxies which show
consistent assembly times at all radii. Hence, we refer to these galaxies as
Inside-Out Assembled Galaxy (IOAG) candidates. We find that the majority of
IOAG candidates with well-detected emission lines are classified as either AGN
(40%) or composite (40%) in the BPT diagram. We also find that the majority of
our sources are located below the main sequence of star formation, and within
the green valley or red sequence. Most BPT-classified star-forming IOAG
candidates have spiral morphologies and are in the main sequence, whereas
Seyfert 2 and composites have mostly spiral morphologies but quiescent star
formation rates (SFRs). We argue that a high fraction of IOAG candidates seem
to be in the process of quenching, moving from the blue cloud to the red
sequence. Those classified as AGN have systematically lower SFRs than
star-forming galaxies suggesting that AGN activity may be related to this
quenching. However, the spiral morphology of these galaxies remains in place,
suggesting that the central star-formation is suppressed before the
morphological transformation occurs.
