Title: Star Clusters in Intermediate-Age Galaxy Merger Remnants
Authors: Bryan W. Miller, Gelys Trancho, David Palamara, and Francois Schweizer
Abstract:
Studies of globular cluster systems play a critical role in our understanding
of galaxy formation.  Star clusters are useful tracers of major star-formation
events in galaxies since they are compact, relatively easy to detect, and have
properties well described by simple-stellar-population models.  Imaging with
the Hubble Space Telescope has revealed that young compact star clusters are
formed copiously during galaxy mergers, strengthening theories in which giant
elliptical galaxies are formed through mergers of spirals.  However, the
formation and evolution of globular cluster systems is still not well
understood.  We should be able to observe how cluster systems evolve from the
very young systems with power-law luminosity functions to old systems with
log-normal luminosity functions like those observed in old elliptical galaxies.
Finding intermediate-age cluster systems would constrain theories of cluster
formation and destruction (evaporation, shocking, dynamical friction) as well
as show the significance of merger events in the histories of galaxies. 

We present results of combining HST optical photometry with ground-based
K-band photometry from NIRI and Flamingos-I on Gemini to study the star
cluster systems of five intermediate-age merger remnants.  The galaxies were
chosen based on blue colors and fine structure such as shells and ripples that
are indicative of past interactions.  We find evidence for star clusters with
ages consistent with the estimated merger ages.  The properties
of the star clusters systems and implications for galaxy and star cluster
formation will be discussed.