Spatially resolved star formation and fuelling in galaxy interactions
  We investigate the spatial structure and evolution of star formation and the
interstellar medium (ISM) in interacting galaxies. We use an extensive suite of
parsec-scale galaxy merger simulations (stellar mass ratio = 2.5:1), which
employs the "Feedback In Realistic Environments-" model (fire-2). This
framework resolves star formation, feedback processes, and the multi-phase
structure of the ISM. We focus on the galaxy-pair stages of interaction. We
find that close encounters substantially augment cool (HI) and cold-dense (H2)
gas budgets, elevating the formation of new stars as a result. This enhancement
is centrally-concentrated for the secondary galaxy, and more radially extended
for the primary. This behaviour is weakly dependent on orbital geometry. We
also find that galaxies with elevated global star formation rate (SFR)
experience intense nuclear SFR enhancement, driven by high levels of either
star formation efficiency (SFE) or available cold-dense gas fuel. Galaxies with
suppressed global SFR also contain a nuclear cold-dense gas reservoir, but low
SFE levels diminish SFR in the central region. Concretely, in the majority of
cases, SFR-enhancement in the central kiloparsec is fuel-driven (55% for the
secondary, 71% for the primary) -- whilst central SFR-suppression is
efficiency-driven (91% for the secondary, 97% for the primary). Our numerical
predictions underscore the need of substantially larger, and/or
merger-dedicated, spatially-resolved galaxy surveys -- capable of examining
vast and diverse samples of interacting systems -- coupled with
multi-wavelength campaigns aimed to capture their internal ISM structure.
