Hsi-An Pan (ASIAA); Lihwai Lin (ASIAA); Bau-Ching Hsieh (ASIAA); Jorge K. Barrera-Ballesteros (UNAM); Sebastian F. Sanchez (UNAM); Y. Sophia Dai (NAOC); Maria Argudo-Fernandez (CITEVA); Mederic Boquien (CITEVA); Ryan Keenan (ASIAA); Johan H. Knapen (Instituto de Astrofsica de Canarias); Cheng Li (Tsinghua University); Patricia B. Tissera (Universidad Andres Bello); Rogerio Riffel (Universidade Federal do Rio Grande do Sul); Ting Xiao (Zhejiang University); Fang-Ting Yuan (SHAO)
We present for the first time an empirical picture of spatial extent of interaction-induced star formation activity as a function merger sequence. The sample under study is drawn from the integral field spectroscopy (IFS) survey: Mapping Nearby Galaxies at APO (MaNGA), including 215 star-forming galaxies in pairs/mergers and ~ 1200 star-forming control galaxies. Merger stage is identified according to the morphological signatures and separations of the interacting systems. The effect of interactions is quantified by the global and spatially-resolved SF rate relative to the controls (delta_SFR and delta_SFR_surface_density). Analysis of radial delta_SFR_surface_density profiles show that, galaxy interactions have no significant impact on local SF during the incoming phase; right after the first pericenter passage, delta_SFR_surface_density profile decreases steeply from enhanced to suppressed activity for increasing galactocentric radius. Later on, star formation is extendedly enhanced out to the radius we explore and the enhancement is generally centrally peaked. The extended star formation enhancement is also observed for systems in their apocenters or in the coalescence phase. Our results suggest that interaction-triggered star formation is not restricted to the central region of a galaxy; in addition to the well-known gas inflow, other mechanisms, such as an increase in gas turbulence, may also affect the star formation appearance. Further explorations of a wide range in parameter space of merger configurations (e.g., mass ratio) are required to constrain the physical picture of interaction-induced star formation.