CMB Lensing: reconstruction from polarisation & implications for cosmology from cross correlation with galaxies – Ruth Pearson

Date: Tue. September 24th, 2013, 11:30 am-12:30 pm
Location: Rockefeller 221

CMB Lensing is a probe of the matter distribution between the surface of last scattering and today, which has been measured using CMB temperature data. Signal to noise for lensing reconstruction from CMB polarisation data is expected to be much better, since B modes on small scales should vanish in the absence of lensing. An effect of having data from an incomplete sky is leakage of E mode power in to B mode power. Upcoming data analysis from ground based CMB polarisation instruments must account for this effect. In the first part of my talk I will show results for CMB polarisation lensing reconstruction from small patches of sky, which incorporate the pure B mode estimator to clean up the E-B leakage problem. CMB lensing is also well correlated with the galaxy distribution, indeed CMB lensing was first detected via cross correlation with a radio survey. In the second part of my talk I will show results on cosmology (neutrino mass sum and tau parameters) and astrophysics (bias and redshift distribution parameters) from the joint analysis of CMB lensing and the 2D galaxy power spectrum. It remains to be seen what can be learned about cosmology and astrophysics from this correlation, and our results begin to quantify this.