The merger model for elliptical galaxy
formation has received increasing attention since
it was first suggested by Toomre & Toomre
(1972). Van den Bergh (1984) pointed out a problem
with the idea that elliptical galaxies were formed
by simply combining two, or more, spiral galaxies.
He noted that the specific frequency
(SN, number of globular
clusters per unit galaxy light) is systematically
lower for spirals than for ellipticals. Schweizer
(1987) suggested that globular clusters (GCs)
might be expected to form in the merger process,
thereby alleviating or possibly eliminating the
SN problem. Ashman & Zepf
(1992) developed this idea into a merger model for
GC formation with testable predictions.
We recently examined this model in the
light of new HST and ground-based imaging data on
the blue and red sub-populations of GCs in
elliptical galaxies (Forbes, Brodie &
Grillmair 1997). We concluded that the merger
model for GC formation has serious problems,
particularly in explaining the characteristics of
GCs in giant elliptical galaxies with high
SN. A multi-phase collapse
scenario was suggested as more consistent with the
available evidence.
The Globular Cluster Luminosity Function and Specific Frequency in Dwarf Elliptical Galaxies