Particle Astrophysics and Cosmology

The field of cosmology seeks to ask big questions about the Universe. How did the Universe begin? What is it made of? How will it end? The growth in our understanding of the Cosmos over the past 100 years has been incredible. Even at the time of Einstein’s relativity, scientists did not know that anything existed outside of the Milky Way; whereas we know have a basic understanding of everything out to the edge of the observable Universe. After a brief introduction to the modern field of cosmology, I will turn to the recent hot results in particle astrophysics. Central topics of today’s research are the dark matter and dark energy that constitute 95% of the content of the Universe, and an early inflationary epoch of accelerated expansion. Recent data provide intriguing hints of discovery. Among the best-motivated dark matter candidates are Weakly Interacting Massive Particle (WIMPs) and sterile neutrinos, and there are hotly debated signals in detectors for these two possibilities. Inflation, which seeks to explain the large-scale homogeneity and isotropy as well as the oldness of the Universe, produces the density fluctuations that are responsible for formation of structure as well as gravitational waves. The basic predictions of inflation have proven true, and individual models are now being tested. Most models have been ruled out, and my model of Natural Inflation is a good fit to all data. I will discuss recent excitement about claimed detection of gravity waves at the South Pole, and will end with a discussion of future research directions.