Cosmology seminar: Harald Thommesen: The CMB Dipole – A Monte Carlo comparison between dipole estimators
Harald Thommesen is a Ph.D. student at ITA.
The CMB dipole is the largest anisotropy in the CMB sky and is caused by the movement of the observer with respect to the CMB rest frame. Knowing the dipole parameters is of utmost importance for CMB experiments, since it serves as a tool for both relative and absolute data calibration. Partial sky-coverage created by masking galactic emission leads to leakage from higher-order fluctuations into the dipole component, and therefore complicates the procedure of dipole estimation. In this talk I will present two different dipole estimators and compare their relative performance by means of Monte Carlo simulations. The first method amounts to simple template-fitting, while the second method makes use of Wiener filtering and thereby considers the coupling with higher-order modes. I will show that using the Wiener filter approach, we are able to significantly reduce the mask-induced uncertainty on the dipole parameters.