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Event Number 2849
Tuesday, November 13th, 2012
 Theory Seminar (High Energy/Cosmology)
 Cosmological Perturbations: Isocurvature, Vorticity and Magnetic Fields
 Time: 4:00 pm
 Place: 5280 Chamberlin
 Speaker: Adam Christopherson, University of Nottingham
 Abstract: In this talk I will discuss some recent, complementary work that I have undertaken using cosmological perturbation theory, a powerful technique for modeling inhomogeneities in the universe. After a brief review of the basics, I introduce isocurvature, or nonadiabatic pressure perturbations, and calculate their spectrum in the settings of standard, concordance cosmology, and inflationary models involving two scalar fields. I then extend the discussion beyond linear perturbations, and show that vorticity can be sourced at second order with only scalar perturbations, the source term being quadratic in the gradients of first order energy density and nonadiabatic pressure perturbations. I present a first estimate of this vorticity's power spectrum, and highlight some potential observational consequences. One of these is the possible sourcing of sizeable magnetic fields, and I briefly sketch some current work on including magnetic fields in perturbation theory in a consistent way. I close with some ideas for future work.
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