The VIMOS VLT Deep Survey: the contribution of minor mergers to the
  growth of L_B >= L*_B galaxies since z ~ 1 from spectroscopically identified
  pairs
  In this work we measure the merger fraction, f_m, of L_B >= L*_B galaxies in
the VVDS-Deep spectroscopic Survey. We define kinematical close pairs as those
galaxies with a separation in the sky plane 5h^-1 kpc < r_p <= r_p^max and a
relative velocity Delta v <= 500 km s^-1 in redshift space. We vary r_p^max
from 30h^-1 kpc to 100h^-1 kpc. We study f_m in two redshift intervals and for
several values of mu, the B-band luminosity ratio of the galaxies in the pair,
from 1/2 to 1/10. We take mu >= 1/4 and 1/10 <= mu < 1/4 as major and minor
mergers. The merger fraction increases with z and its dependence on mu is
described well as f_m (>= mu) proportional to mu^s. The value of s evolves from
s = -0.60 +- 0.08 at z = 0.8 to s = -1.02 +- 0.13 at z = 0.5. The fraction of
minor mergers for bright galaxies evolves with redshift as a power-law (1+z)^m
with index m = -0.4 +- 0.7 for the merger fraction and m = -0.5 +- 0.7 for the
merger rate. We split our principal galaxies in red and blue by their
rest-frame NUV-r colour, finding that i) f_m is higher for red galaxies, ii)
f_m^red does not evolve with z, and iii) f_m^blue evolves dramatically. Our
results show that the mass of normal L_B >= L*_B galaxies has grown ~25% since
z ~ 1 because of minor and major mergers. The relative contribution of the mass
growth by merging is ~25% due to minor mergers and ~75% due to major ones. The
relative effect of merging is more important for red than for blue galaxies,
with red galaxies subject to 0.5 minor and 0.7 major mergers since z~1, which
leads to a mass growth of ~40% and a size increase by a factor of 2. Our
results also suggest that, for blue galaxies, minor mergers likely lead to
early-type spirals rather than elliptical galaxies. These results show that
minor merging is a significant but not dominant mechanism driving the mass
growth of galaxies in the last ~8 Gyr (Abriged).
