Feedback and feeding in the context of galaxy evolution with SPICA:
  direct characterization of molecular outflows and inflows
  A far-infrared observatory such as the {\it SPace Infrared telescope for
Cosmology and Astrophysics} ({\it SPICA}), with its unprecedented spectroscopic
sensitivity, would unveil the role of feedback in galaxy evolution during the
last $\sim10$ Gyr of the Universe ($z=1.5-2$), through the use of far- and
mid-infrared molecular and ionic fine structure lines that trace outflowing and
infalling gas. Outflowing gas is identified in the far-infrared through P-Cygni
line shapes and absorption blueshifted wings in molecular lines with high
dipolar moments, and through emission line wings of fine-structure lines of
ionized gas. We quantify the detectability of galaxy-scale massive molecular
and ionized outflows as a function of redshift in AGN-dominated,
starburst-dominated, and main-sequence galaxies, explore the detectability of
metal-rich inflows in the local Universe, and describe the most significant
synergies with other current and future observatories that will measure
feedback in galaxies via complementary tracers at other wavelengths.
