12:00–1:00 pm ERC 401
Emmanuel Schaan, Lawrence Berkeley National Laboratory, "Lensing of the CMB and intensity maps: analogy with galaxy lensing and application to foreground cleaning"
Host: Anne Gambrel
Current CMB lensing measurements rely heavily on temperature (vs polarization). In this regime, extragalactic foregrounds produce significant lensing biases, which are difficult to control with frequency cleaning or masking. After reviewing existing methods, I will clarify the analogy between galaxy lensing and CMB lensing, and use it to split the standard CMB lensing quadratic estimator into shear-only and magnification-only estimators. The different symmetries of the lensed CMB and extragalactic foregrounds make the shear-only estimator robust to this contamination, as I will demonstrate with realistic simulations. I will generalize these estimators to optimal "multipole" estimators, and show one avenue to generalize them to polarization and maximum likelihood lensing methods. Furthermore, extragalactic foregrounds are emitted at cosmological distances, and are therefore themselves lensed. This causes an additional bias to CMB lensing, but is also potentially a new signal. I will propose a method to measure the lensing of foregrounds like the cosmic infrared background, and of intensity maps like the 21cm.