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Physics Colloquium: Searching for Dark Matter Using the Cosmic Microwave Background

Thursday, October 19, 2017

3:30 PM-4:30 PM

Daniel Grin, PhD, Haverford College


The dark matter holding together galaxies and the dark energy driving today's cosmic acceleration are persistent mysteries. In contrast to the prevailing paradigm, I will examine the possibility that dark matter is composed of a hypothetical ultra-light particle, called an axion. I'll begin by summarizing the particle physics that first lead to the axion hypothesis. By changing the expansion history of the universe and the clustering properties of dark matter, axions could have a detectable presence in astronomical data, changing the properties of the microwave afterglow of the Big Bang the distribution of galaxies today. I'll discuss the physics of these imprints and the work of collaborators and me to test for the presence of axions using Planck cosmic microwave background data, as well as data from galaxy surveys. I'll present constraints from completed experiments, survey the promise of upcoming/hoped-for experiments, and conclude by explaining what axions might have to do with the physics of inflation, the exponential growth of the universe during the first 10-32 seconds of cosmic time.

Contact Information

Gordon Richards

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Disque Hall, Room 919, 32 South 32nd Street, Philadelphia, PA 19104


  • Undergraduate Students
  • Graduate Students
  • Faculty