Bibcode
Bekki, K.; Forbes, Duncan A.; Beasley, M. A.; Couch, W. J.
Referencia bibliográfica
Monthly Notice of the Royal Astronomical Society, Volume 335, Issue 4, pp. 1176-1192.
Fecha de publicación:
10
2002
Número de citas
85
Número de citas referidas
76
Descripción
We investigate the spatial, kinematic and chemical properties of
globular cluster systems formed in merging and interacting galaxies
using N-body-smoothed particle hydrodynamics (SPH) simulations. Although
we cannot resolve individual clusters in our simulation, we assume that
they form in collapsing molecular clouds when the local external gas
pressure exceeds 105kB (where kB is the
Boltzmann constant). Several simulations are carried out for a range of
initial conditions and galaxy mass ratios. The input model spirals are
given a halo globular cluster system similar to those observed for the
Milky Way and M31. Gravitational tidal effects during galaxy merging and
interaction lead to a dramatic increase in gas pressure, which exceeds
our threshold and hence triggers new globular cluster formation. We
investigate the properties of the globular cluster system in the remnant
galaxy, such as the number density, the specific frequency, kinematic
properties and the metallicity distribution. Different orbital
conditions and mass ratios give rise to a range in globular cluster
properties, particularly for the interaction models. Our key results are
the following: the newly formed metal-rich clusters are concentrated at
the centre of the merger remnant elliptical, whereas the metal-poor ones
are distributed to the outer parts because of strong angular momentum
transfer. The dissipative merging of present-day spirals, including
chemical evolution, results in metal-rich clusters with a mean
metallicity that is super-solar, i.e. much higher than is observed in
elliptical galaxies. If elliptical galaxies form by dissipative major
mergers, then they must do so at very early epochs when their discs
contained low-metallicity gas. Our simulations show that the specific
frequency can be increased in a dissipative major merger. However, when
this occurs it results in a ratio of metal-poor to metal-rich clusters
that is less than one, contrary to the ratio observed in many elliptical
galaxies.