Friday, November 16, 2012
2:00 pm
Cahill 370

TAPIR Seminar

Cosmological Perturbations: Isocurvature, Vorticity and Magnetic Fields
Adam Christopherson, Research Fellow, Center for Astronomy and Particle Physics, University of Nottingham

In this talk I will discuss some recent, complementary work that I have undertaken using cosmological perturbation theory,
a powerful technique for modelling inhomogeneities in the universe. After a brief review of the basics, I introduce isocurvature,
or non-adiabatic 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 non-adiabatic 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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