SDSS-IV MaNGA: Environmental dependence of gas metallicity gradients in
  local star-forming galaxies
  Within the standard model of hierarchical galaxy formation in a {\Lambda}CDM
Universe, the environment of galaxies is expected to play a key role in driving
galaxy formation and evolution. In this paper we investigate whether and how
the gas metallicity and the star formation surface density ({\Sigma}_SFR)
depend on galaxy environment. To this end we analyse a sample of 1162 local,
star-forming galaxies from the galaxy survey Mapping Nearby Galaxies at APO
(MaNGA). Generally, both parameters do not show any significant dependence on
environment. However, in agreement with previous studies, we find that low-mass
satellite galaxies are an exception to this rule. The gas metallicity in these
objects increases while their {\Sigma}SFR decreases slightly with environmental
density. The present analysis of MaNGA data allows us to extend this to
spatially resolved properties. Our study reveals that the gas metallicity
gradients of low-mass satellites flatten and their {\Sigma}SFR gradients
steepen with increasing environmental density. By extensively exploring a
chemical evolution model, we identify two scenarios that are able to explain
this pattern: metal-enriched gas accretion or pristine gas inflow with varying
accretion timescales. The latter scenario better matches the observed
{\Sigma}SFR gradients, and is therefore our preferred solution. In this model,
a shorter gas accretion timescale at larger radii is required. This suggests
that 'outside-in quenching' governs the star formation processes of low-mass
satellite galaxies in dense environments.
