SDSS-IV MaNGA: Properties of galaxies with kinematically decoupled
  stellar and gaseous components
  We study the properties of 66 galaxies with kinematically misaligned gas and
stars from MaNGA survey. The fraction of kinematically misaligned galaxies
varies with galaxy physical parameters, i.e. M*, SFR and sSFR. According to
their sSFR, we further classify these 66 galaxies into three categories, 10
star-forming, 26 "Green Valley" and 30 quiescent ones. The properties of
different types of kinematically misaligned galaxies are different in that the
star-forming ones have positive gradient in D4000 and higher gas-phase
metallicity, while the green valley/quiescent ones have negative D4000
gradients and lower gas-phase metallicity on average. There is evidence that
all types of the kinematically misaligned galaxies tend to live in more
isolated environment. Based on all these observational results, we propose a
scenario for the formation of star forming galaxies with kinematically
misaligned gas and stars - the progenitor accretes misaligned gas from a
gas-rich dwarf or cosmic web, the cancellation of angular momentum from gas-gas
collisions between the pre-existing gas and the accreted gas largely
accelerates gas inflow, leading to fast centrally-concentrated star-formation.
The higher metallicity is due to enrichment from this star formation. For the
kinematically misaligned green valley and quiescent galaxies, they might be
formed through gas-poor progenitors accreting kinematically misaligned gas from
satellites which are smaller in mass.
