On the Influence of Minor Mergers on the Radial Abundance Gradient in
  Disks of Milky Way-like Galaxies
  We investigate the influence of stellar migration caused by minor mergers
(mass ratio from 1:70 to 1:8) on the radial distribution of chemical abundances
in the disks of Milky Way-like galaxies during the last four Gyr. A GPU-based
pure N-body tree-code model without hydrodynamics and star formation was used.
We computed a large set of mergers with different initial satellite masses,
positions, and orbital velocities. We find that there is no significant
metallicity change at any radius of the primary galaxy in the case of accretion
of a low-mass satellite of 10$^9$ M$_{\odot}$ (mass ratio 1:70) except for the
special case of prograde satellite motion in the disk plane of the host galaxy.
The accretion of a satellite of a mass $\gtrsim3\times10^9$ M$_{\odot}$ (mass
ratio 1:23) results in an appreciable increase of the chemical abundances at
galactocentric distances larger than $\sim10$ kpc. The radial abundance
gradient flattens in the range of galactocentric distances from 5 to 15 kpc in
the case of a merger with a satellite with a mass $\gtrsim3\times10^9$
M$_{\odot}$. There is no significant change in the abundance gradient slope in
the outer disk (from $\sim15$ kpc up to 25 kpc) in any merger while the scatter
in metallicities at a given radius significantly increases for most of the
satellite's initial masses/positions compared to the case of an isolated
galaxy. This argues against attributing the break (flattening) of the abundance
gradient near the optical radius observed in the extended disks of Milky
Way-like galaxies only to merger-induced stellar migration.
