Calendar

Sep
28
Fri
Colloquium: Bharat Ratra (Host: Anatoly Klypin)
Sep 28 @ 3:15 pm – 4:15 pm
Colloquium: Bharat Ratra (Host: Anatoly Klypin) @ BX102

Spatial Curvature, Dark Energy Dynamics, Neither, or Both?

Bharat Ratra, Kansas State University

Experiments and observations over the two last decades have persuaded cosmologists that (as yet undetected) dark energy is by far the main component of the energy budget of the current universe. I review a few simple dark energy models and compare their predictions to observational data, to derive dark energy model-parameter constraints and to test consistency of different data sets. I conclude with a list of open cosmological questions.
Aug
30
Fri
Colloquium: Lisa Young (Host: Rene Walterbos)
Aug 30 @ 3:15 pm – 4:15 pm
Colloquium: Lisa Young (Host: Rene Walterbos) @ BX102

Cold Gas and the Evolution of Early-type Galaxies

Lisa Young, New Mexico Tech

A major theme of galaxy evolution is understanding how today’s Hubble sequence was
established — what makes some galaxies red spheroidals and others blue disks, and what
drives their relative numbers and their spatial distributions. One way of addressing these
questions is that galaxies themselves hold clues to their formation in their internal
structures. Recent observations of early-type galaxies in particular (ellipticals and
lenticulars) have shown that their seemingly placid, nearly featureless optical images can
be deceptive. Kinematic data show that the early-type galaxies have a wide variety of
internal kinematic structures that are the relics of dramatic merging and accretion
events. A surprising number of the early-type galaxies also contain cold atomic and
molecular gas, which is significant because their transitions to the red sequence must
involve removing most of their cold gas (the raw material for star formation). We can now
also read clues to the evolution of early-type galaxies in the kinematics and the
metallicity of their gas, and possibly also in the rare isotope abundance patterns in the
cold gas. Numerical simulations are beginning to work on reproducing these cold gas
properties, so that we can place the early-type galaxies into their broader context.

(incomplete video)