The Largest Structures in the Universe
Student Nathan Harkema and Professor Deborah Haarsma, Calvin College
Tuesday, February 14, 3:45pm, Science Building 110
The largest galaxies in the universe are hundreds of times larger than our own Milky Way. These huge galaxies are found near the centers of rich galaxy clusters (which are the largest gravitationally bound structures in the universe). For the last few years the Haarsma group has studied these large galaxies in a sample of 70 galaxy clusters, using optical data from the Sloan Digital Sky Survey in New Mexico and X-ray data from the Chandra X-ray Observatory in orbit. We will summarize our conclusions for this sample of clusters, including work from last summer to determine the position of the cluster center. The cluster center is easy to detect in X-ray emission but can be difficult in optical emission. With the known X-ray positions as a reference, we developed a method to estimate the central position using optical data alone.