There are at least four different ways to determine the age of the universe and we are studying all of them. They each seem to give slightly different results. We are exploring the possibility that the apparent differences between age determinations can be ascribed to different aspects of the galaxy formation process. We also explore various scenarios for galaxy formation. Constraints on these scenarios from various observational and theoretical evidence are being used to construct a consistent picture in which the Galaxy is assembled from merging protogalactic clouds within a gravitational potential which may or may not be dominated by cold dark matter. Bursts of star formation associated with the mergers lead naturally to a star formation rate in which the star formation in the disk can be delayed by several billion years relative to the formation of the oldest stars in globular clusters. We are also studying whether these bursts of star formation are the birth place of the recently observed gravitational microlensing objects in the halo. We study the evolution of the solar neighborhood after the merging epoch as gas settles into the local thin disk. When analyzed within this context, the various chronometers are all consistent with a relatively old age for the universe (15 billion years).
For more information about this research project of the Astrophysics Group, please send us an e-mail to gmathews@nd.edu.