Dr. Susan Kassin, UC Santa Cruz

"The Formation and Evolution of Disk Galaxies
From z~1 to Now: Constraints from New Observations"


Abstract:
In the currently accepted picture of disk galaxy formation,
baryons that are initially well-mixed with dark matter
dissipate and form disks at the centers of potential wells.
Detailed observations both locally and at high redshift are
now giving us insight into the specifics of how and when this
process occurs.  From optical and near-infrared photometry
and rotation curves of a sample of 34 local bright spiral
galaxies, we investigate radial baryonic and dark matter
distributions.  The specific angular momenta of these galaxies
are also examined in an integrated and a radial sense.
Discrepancies are found between the observed dark matter and
specific angular momentum distributions and what is expected
from theory, and we discuss their implications.  For a sample
of 544 galaxies of a large range of morphologies at
0.1 < z < 1.2, HST images and resolved spectra from Keck are
used to create a stellar mass Tully-Fisher relation.  A
remarkable regularity is found when we construct such a
relation by incorporating both rotation velocity and
velocity dispersion.  This trend reflects a regularity
in the processes that led to the formation of galaxies
and differs from what is expected from theory.