Environmental effects in the interaction and merging of galaxies in
  zCOSMOS
  (Abridged) We analyze the environments and galactic properties (morphologies
and star-formation histories) of a sample of 153 close kinematic pairs in the
redshift range 0.2 < z < 1 identified in the zCOSMOS-bright 10k spectroscopic
sample of galaxies. Correcting for projection effects, the fraction of close
kinematic pairs is three times higher in the top density quartile than in the
lowest one. This translates to a three times higher merger rate because the
merger timescales are shown, from mock catalogues based on the Millennium
simulation, to be largely independent of environment once the same corrections
for projection is applied. We then examine the morphologies and stellar
populations of galaxies in the pairs, comparing them to control samples that
are carefully matched in environment so as to remove as much as possible the
well-known effects of environment on the properties of the parent population of
galaxies. Once the environment is properly taken into account in this way, we
find that the early-late morphology mix is the same as for the parent
population, but that the fraction of irregular galaxies is boosted by 50-75%,
with a disproportionate increase in the number of irregular-irregular pairs
(factor of 4-8 times), due to the disturbance of disk galaxies. Future
dry-mergers, involving elliptical galaxies comprise less than 5% of all close
kinematic pairs. In the closest pairs, there is a boost in the specific
star-formation rates of star-forming galaxies of a factor of 2-4, and there is
also evidence for an increased incidence of post star-burst galaxies. Although
significant for the galaxies involved, the "excess" star-formation associated
with pairs represents only about 5% of the integrated star-formation activity
in the parent sample. Although most pair galaxies are in dense environments,
the effects of interaction appear to be largest in the lower density
environments.
