Galaxy triplets in Sloan Digital Sky Survey Data Release 7 - III.
  Analysis of Configuration and Dynamics
  We analyse the spatial configuration and the dynamical properties of a sample
of 92 galaxy triplets obtained from the SDSS-DR7 (SDSS-triplets) restricted to
have members with spectroscopic redshifts in the range $0.01\le z \le 0.14 $
and absolute r-band luminosities brighter than $M_r=-20.5$. The configuration
analysis was performed through Agekyan & Anosova map (AA-map). We estimated
dynamical parameters, namely the radius of the system, the velocity dispersion,
a dimensionless crossing-time and the virial mass. We compared our results with
those obtained for a sample of triplets from the catalogue "Isolated Triplets
of Galaxies" (K-triplets) and a sample of Compact Groups. We have also studied
a mock catalogue in order to compare real and projected configurations, and to
estimate the three dimensional dynamical parameters of the triple systems. We
found that the SDSS-triplets prefer alignment configurations while K-triplets
present an uniform distribution in the AA-map. From the dynamical analysis we
conclude that the SDSS-triplets, K-triplets and Compact Groups present a
similar behaviour comprising compact systems with low crossing-time values,
with velocity dispersions and virial masses similar to those of low mass loose
groups. Moreover, we found that observed and simulated triplets present similar
dynamical parameters. We also performed an analysis of the dark matter content
of galaxy triplets finding that member galaxies of mock triplets belong to the
same dark matter halo, showing a dynamical co-evolution of the system. These
results suggest that the configuration and dynamics of triple systems favour
galaxy interactions and mergers.
