NBIA Colloquium by Katherine Freese – Niels Bohr Institute - University of Copenhagen

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NBIA Colloquium by Katherine Freese

Inflationary Cosmology in Light of Cosmic Microwave Background Data

Katherine Freese

(NORDITA, Stockholm and University of Michigan)

Inflation, a period of accelerated expansion at the beginning of the Universe, seeks to explain the (otherwise mysterious) large scale smoothness, isotropy, and “oldness” of the Universe.  An important product of this inflationary epoch is the origin of density perturbations that are the seeds of galaxies and other large structures today. The density perturbations and gravity waves produced by inflation provide sensitive tests of both the inflationary paradigm and of individual inflationary models.  In the past decade predictions of inflation have been tested and ESA’s Planck satellite in particular has made key observations.  The basic idea of inflation matches the data and sensitive tests have been made of individual models.  Thousands of inflation models have now been ruled out. The original natural inflation that my collaborators and I proposed in 1990, as well as modern variants, provide among the best fit to the data.   Natural inflation uses “axions” as the inflaton, where the term “axion” is used loosely for a field with a flat potential as a result of a shift symmetry.  The successes of inflation as well as the potential discoveries in upcoming data will be emphasized.

All  are welcome!  Refreshments will served in the NBIA lounge after the talk.