Day 1201

Monday.  Tuesday.

1612.05637
CMB lens sample covariance and consistency relations
Motloch, Hu, Benoit-Lévy

GL information from the 2 and higher point statistics of the CMB temperature and polarization fields are intrinsically correlated because they are lensed by the same realization of structure between last scattering and observation.  Using an analytic model for lens sample covariance, show that there is one mode, separately measurable in the lensed CMB PS and lensing reconstruction, that carries most of this correlation.  Once these measurements become lens sample variance dominated, this mode should provide a useful consistency check between the observable that is largely free of sampling and cosmo parameter errors.  Violations of consistency could indicate systematic errors in the data and lens reconstruction or new physics at last scattering, any of which could bias cosmo inferences and delensing for gravitational waves.  A second mode provides a weaker consistency check for a spatially flat universe.  The analysis isolates the additional information supplied by lensing in a model independent manner but is also useful for understanding and forecasting CMB cosmo parameter errors in the extended LCDM parameter space of DE, curvature and massive neutrinos.  Introduce and test a simple but accurate forecasting technique for this purpose that neither double counts lensing information nor neglects lensing in the observables.


1612.05647
The VIMOS public extragalactic redshift survey (VIPERS).  Gravity test from the combination of redshift-space distortions and galaxy-galaxy lensing at $0.5<z<1.2$
de la Torre, Jullo, Giocoli, et al

Carry out a joint analysis of z-space distortions and gg lensing, with the aim of measuring the growth rate of structure; this is a key quantity for understanding the nature of gravity on cosmo scales and late-time cosmic acceleration.  Make use of the final VIPERS z survey dataset, which maps a portion of the Universe at a z of z~0.8, and the lensing data from the CFHTLenS survey over the same area of the sky.  Build a consistent theoretical model that combines non-linear galaxy biasing and z-space distortion models, and confront it with observations.  The two probes are combined in a Bayesian maximum likelihood analysis to determine the growth rate of structure at 2 redshifts z-0.6 and 0.86.  Obtain measurement of f sigma8(0.6)=0.48±0.12 and f sigma8(0.886)=0.48±0.10.  The additional gg lensing constraint alleviates galaxy bias and sigma8 degeneracies, providing direct measurements of [f,sigma8](0.6) = [0.93±0.22, 0.52±0.06] and [f,sigma8](0.86) = [0.99±0.19, 0.48±0.04].  These measurements are statistically consistent with a Universe where the gravitational interactions can be described by GR, although they are not yet accurate enough to rule out some commonly considered alternatives.  Finally, as a complementary test, measure the gravitational slip parameter, E_G, for the first time at z>0.6.  Find values of E_G(0.6)=0.16±0.09 and E_G(0.86)=0.09±).07, when E_G is averaged over scales above 3 h^-1 Mpc.  Find that the E_G measurements exhibit slightly lower values than expected for standard relativistic gravity in a LCDM background, although the results are consistent with 1-2 sigma.