SDSS-IV MaNGA: Spatial Evolution of Star Formation Triggered by Galaxy
  Interactions
  Galaxy interaction is considered a key driver of galaxy evolution and star
formation (SF) history. In this paper, we present an empirical picture of the
radial extent of interaction-triggered SF along the merger sequence. The
samples under study are drawn from the integral field spectroscopy (IFS) survey
SDSS-IV MaNGA, including 205 star-forming galaxies in pairs/mergers and ~1350
control galaxies. For each galaxy in pairs, the merger stage is identified
according to its morphological signatures: incoming phase, at first pericenter
passage, at apocenter, in merging phase, and in final coalescence. The effect
of interactions is quantified by the global and spatially resolved SF rate
relative to the SF rate of a control sample selected for each individual galaxy
($\Delta$logSFR and $\Delta$logsSFR(r), respectively). Analysis of the radial
$\Delta$logsSFR(r) distributions shows that galaxy interactions have no
significant impact on the $\Delta$logsSFR(r) during the incoming phase. Right
after the first pericenter passage, the radial $\Delta$logsSFR(r) profile
decreases steeply from enhanced to suppressed activity for increasing
galactocentric radius. Later on, SF is enhanced on a broad spatial scale out to
the maximum radius we explore (~6.7 kpc) and the enhancement is in general
centrally peaked. The extended SF enhancement is also observed for systems at
their apocenters and in the coalescence phase, suggesting that
interaction-triggered SF is not restricted to the central region of a galaxy.
Further explorations of a wide range in parameter space of merger
configurations (e.g., mass ratio) are required to constrain the whole picture
of interaction-triggered SF.
