2-6 September 2019
Europe/Zurich timezone

CMB Lensing Measurements from the SPTpol 500 deg$^2$ survey

4 Sep 2019, 15:45
Talk CMB, Universe Expansion, and Thermal History Parallel Sessions: CMB, Expansion Rate, Thermal History (C.A.R.L., H09)


Dr W.L. Kimmy Wu (UChicago/KICP)


Gravitational lensing of the cosmic microwave background (CMB) encodes information from the low-redshift universe. Therefore, its measurement is useful for constraining cosmological parameters that describe structure formation, e.g. $\Omega_M$, $\sigma_8$ and the sum of neutrino masses. In this talk, I will present a measurement of the CMB lensing potential and its power spectrum using data from the SPTpol 500 deg$^2$ survey. From the minimum-variance combination of the lensing estimators from all combinations of SPTpol temperature and polarization data, we measure the lensing amplitude $A_{\rm MV} = 0.944 \pm 0.058 ({\rm Stat.}) \pm 0.025 ({\rm Sys.})$, which constitutes the tightest lensing amplitude measurement using ground-based CMB data alone. Restricting to only polarization data, we measure the lensing amplitude $A_{\rm Pol} = 0.906 \pm 0.090 ({\rm Stat.}) \pm 0.040 ({\rm Sys.})$, which is more constraining then our measurement using only temperature data. As SPT-3G, the successor to SPTpol, and other CMB experiments continue to lower the CMB map noise levels, polarization data will dominate the signal-to-noise of lensing measurements for angular multipoles below at least several hundred. Looking to the future, high signal-to-noise measurements of lensing enabled by deep polarization maps is crucial for constraining the sum of neutrino masses and the amplitude of inflationary gravitational waves through delensing.

Primary authors

Dr W.L. Kimmy Wu (UChicago/KICP) L. Monica Mocanu (University of Oslo) South Pole Telescope Collaboration

Presentation Materials