Collaborative Research: Investigating the nature of dark matter with gravitational lensing

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Understanding the nature of dark matter is one of the most pressing issues in all of modern astrophysics. This mysterious substance makes up the vast majority of the material in galaxies, including our own Milky Way Galaxy, but does not appear in any images taken of these objects. Furthermore, dark matter is one of the two major components, along with dark energy, that make up the Universe. While the properties of dark matter are not well known, relatively simple models of it have done a remarkable job of reproducing the distribution of galaxies in the Universe. However, when looking on smaller scales, the models predict that thousands of small galaxies should orbit galaxies such as the Milky Way, while careful observations of the Milky Way have detected fewer than 50 satellite galaxies. The primary goal of this project is to build up and analyze a large enough sample of rare gravitational lens systems to distinguish between different models of dark matter and, thus, to further our knowledge about one of the most important components of the Universe. The excitement of this program will be shared with the public, with a special emphasis on introducing young people to the scientific method and to the techniques of cutting-edge astrophysics research. This will be accomplished through specialized summer programs for high-school students, introductory-level college classes in astronomy and sustainable energy, and research projects for undergraduates. The fundamental question underlying this project is "what is the nature of dark matter?". We now know that dark matter is a major component of the mass energy of the Universe, second only to dark energy, and completely dominates the mass of galaxies and galaxy clusters. However, the properties of the dark matter particle are not well quantified with efforts to measure these properties proceeding both in astrophysics and physics. The proposed research utilizes four steps to better understand dark matter: (1) building better statistics by applying our gravitational imaging and flux-ratio anomaly techniques to new samples that will provide a significant increase over our current numbers, (2) significantly improving the power of the lensing approach to disentangle cold and warm dark matter by pushing orders of magnitude down the mass function of substructures, (3) develop techniques to reduce systematic errors that are now known to have affected earlier dark matter analyses, and (4) do at least two independent measurements of the substructure mass function in distant galaxies and analyze the results in the context of alternative dark matter models.