Mergers of Gas-Rich
Disk Galaxies
Mergers may transform gas-rich disk galaxies into some types of
elliptical galaxies, or even into S0 galaxies. The outcome of a
disk-galaxy merger depends on the relative sizes of the galaxies
and on the behavior of the gas. These simulations illustrate
the formation of extended gas disks in merger remnants.
Stellar
Collisions
Close encounters between stars are very rare; only a few of the
stars in a typical galaxy ever undergo collisions. Nonetheless,
collisions between stars play a role in formation of exotic
stellar systems. Here are some simple model calculations of
stellar collisions.
Tidal Dwarf
Pseudo-Galaxies
Gravitational collapse in tidal tails can produce bound
structures. I study this process using numerical simulations of
encounters between equal-mass disk galaxies, systematically
changing encounter parameters to see which factors favor or
inhibit the formation of these objects.
Models of
Interacting Galaxies
Numerical modeling is an effective way to test the tidal origins
of peculiar galaxies. In addition, detailed modeling of
individual systems complements and helps in the interpretation
of observational data.
Mergers of `Cuspy' Galaxies
Galactic spheroids have density profiles scaling as
r-1 or r-2 at small radii. Can bright
spheroids, which have shallow profiles, be assembled from faint
spheroids, which have steep profiles? How does the profile
influence the merging process and the remnant's distribution
function and radial structure?
Orbit Classification
Triaxial galaxies with steep density profiles support a wide
range of orbits. Fulton & Barnes
(2001) developed an algorithm to classify orbits in 2-D
potentials; generalizations to 3-D and applications to N-body
simulations are in progress. Shown here are orbits starting
from rest in a logarithmic potential.
Halo
Noise
Models of structure formation by gravitational clustering
predict that galaxy halos may contain a broad spectrum of
substructure. These `subhalos' could perturb galactic disks and
heat them to unacceptable levels. We use self-consistent N-body
experiments to study this effect and set limits on acceptable
levels of halo substructure.