Marshall H. Cohen

My research is in extragalactic astronomy, mostly on active galactic nuclei and quasars. Using the large telescopes at Palomar and Keck Observatories, I make polarization observations of the spectrum and the image. The objectives are to study the relations among the different classes of objects and their evolution. I also make radio measurements with the Very Long Baseline Array, studying the very fine structure of these objects. Statistical analysis of the structure and internal motions gives information on the physics in these objects and on cosmology.