Star formation is boosted (and quenched) from the inside out: radial
  star formation profiles from MaNGA
  The tight correlation between total galaxy stellar mass and star formation
rate (SFR) has become known as the star forming main sequence. Using ~487,000
spaxels from galaxies observed as part of the Sloan Digital Sky Survey Mapping
Galaxies at Apache Point Observatory (MaNGA) survey, we confirm previous
results that a correlation also exists between the surface densities of star
formation (Sigma_SFR) and stellar mass (Sigma_mass) on kpc scales, representing
a `resolved' main sequence. Using a new metric (Delta Sigma_SFR), which
measures the relative enhancement or deficit of star formation on a
spaxel-by-spaxel basis relative to the resolved main sequence, we investigate
the SFR profiles of 864 galaxies as a function of their position relative to
the global star forming main sequence (Delta SFR). For galaxies above the
global main sequence (positive Delta SFR) Delta Sigma_SFR is elevated
throughout the galaxy, but the greatest enhancement in star formation occurs at
small radii (< 3 kpc, or 0.5 R_e). Moreover, galaxies that are at least a
factor of three above the main sequence show diluted gas phase metallicities
out to 2 R_e, indicative of metal-poor gas inflows accompanying the starbursts.
For quiescent/passive galaxies that lie at least a factor of 10 below the star
forming main sequence there is an analogous deficit of star formation
throughout the galaxy with the lowest values of Delta Sigma_SFR in the central
3 kpc. Our results are in qualitative agreement with the `compaction' scenario
in which a central starburst leads to mass growth in the bulge and may
ultimately precede galactic quenching from the inside-out.
