blackboard

waynehu

Professor, Department of Astronomy and Astrophysics
University of Chicago

Group Contact CV SnapShots
CMB Introduction '96   Intermediate '01   Polarization Intro '01   Cosmic Symphony '04   Polarization Primer '97   Review '02   Power Animations   Lensing   Power Prehistory   Legacy Material '96   PhD Thesis '95 Baryon Acoustic Oscillations Cosmic Shear Clusters
Transfer Function WMAP Likelihood Reionization PPF for CAMB Halo Mass Conversion Cluster Abundance
Cosmology I [legacy 321] Cosmology II [321] Current Topics [282] Galaxies and Universe [242] Radiative Processes [305] Research Preparation [307] GR Perturbation Theory [408] CMB [448] Cosmic Acceleration [449]

Polarization Pattern

The projection cold (red) lobe of the quadrupole moment of the temperature anisotropy at last scattering (recombination or reionization) transverse to the line of site deterines the polarization magnitude and direction. Here the effect of a scalar or density perturbation is shown. Note the azimuthal symmetry of the pattern.

EB Modes

Polarization patterns can be decomposed into the E and B modes which are polarization analogues of the curl free and divergence free parts of vectors.

E and B modes have opposite behavior under a parity transform corresponding to the B modes having a polarization direction (north-west to south-east and north-east to south west) that is 45 degrees from the principal axis for its amplitude variation (north-south).

Unlike the scalar mode, vectors (vorticity) and tensors (gravitational waves) carry extra directional information that breaks the symmetry of a pure E mode and stimulates a B mode.

Here the tensor quadrupole (right) is compared to the scalar quadrupole (left) rotating in projection from the equator to the pole and back as in the first figure. Note the breaking of the north-south azimuthal symmetry.