CP3 Mini-Course: Large Scale Anisotropy in the Universe

Who: Pankaj Jain (Indian Institute of Technology)
When: Thursday, June 9, 2016 at 14:00
Wednesday, June 15, 2016 at 11:00
Wednesday, June 22, 2016 at 11:00

Where: The CP³ meeting room

The cosmological principle is an assumption and does not follow from fundamental principles. There are many indications that it might be violated. I will review these observations and the theoretical attempts to model them. The most prominent effects are the observed dipole anisotropies in radio source distribution, brightness, polarized flux and polarization orientations. All of these suggest a preferred direction pointing roughly towards the Virgo supercluster. The direction also approximately agrees with the CMBR dipole and, surprisingly, the CMBR quadrupole and octopole also point roughly in this direction. Another interesting effect is the hemispherical anisotropy seen in CMBR.
Theoretically I will argue that the isotropy and homogeneity of the Universe arises only due to inflation. The Universe need not satisfy this property before inflation. Hence during the early stages of inflation it could be anisotropic and/or inhomogeneous. I will show that perturbation modes generated during this early phase can affect physics today and can lead to the observed anisotropies. I will discuss some explicit primordial models which explain these observations.

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