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Cosmic strings, effective number of neutrinos, gravity waves and the CMB

Tuesday 4th December 2012 - 12:10 to 12:30
INI Seminar Room 1
Session Title: 
Topological evolution in gauge theories and cosmology
Session Chair: 
Tanmay Vachaspati
We will report about recent work concerning cosmic defects, gravity waves and the CMB. On one hand, we simulate a scaling network of cosmic defects, and predict the background gravity wave emission coming from them. On the other, we study degeneracies in the CMB data between cosmic strings and gravity waves. When one tries to fit the CMB data with the effective number of neutrinos as a free parameter, the data prefers a higher number effective neutrinos. There have been works suggesting that the extra relativistic signal could come from gravity waves, and those waves could be created by cosmic defects. We perform a full analysis of the system taking into account the signal that such a network would create, its effect into the effective number of neutrinos, and how those parameters interplay in trying to fit different probes of CMB and other cosmological data.
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Presentation Material: 
University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons