Schedule by Session

We are now entering into an era of precision cosmology, with present data sets testing the current paradigm to high accuracy. Next generation surveys will have a high sky coverage and increased sensitivity, with the ability to probe cosmology in a variety of ways. This opens up new possibilities for what can be done with these data sets. By combining them we can access new information about our Universe and remove systematics that plague our ability to measure cosmology accurately. Cross–correlations in the context of cosmology measure the similarity between two data sets probing the same underlying matter density. Observations of the CMB at high redshift and of weak galaxy lensing at lower redshifts have been shown to be capable of constraining the cosmology of our Universe to high precision (Planck Collaboration et al., 2016; Hildebrandt et al., 2016b; Erben et al., 2013). However there is currently tension between these two measurements (MacCrann et al., 2015). To be fully resolved, this requires a full understanding of systematics and potentially new physics.

CMB lensing and galaxy lensing are complimentary cosmological probes since CMB lensing is sensitive to structure at high redshift, while galaxy lensing traces structure at later times. They are two different probes of the dark matter, neither of which are biased tracers, with both suffering from different systematics. To date there have been only a few papers which have measured the CMB lensing/galaxy lensing cross correlation, with some of these results hinting at a deviation from Planck cosmology. We show prospects for improving this measurement with new CMB lensing data from the Atacama Cosmology Telescope and with galaxy lensing measurements from CS82, RCSLens, CFHTLenS and KiDS, and describe the analysis of these datasets.