Day 1273

Monday.


1706.05004
KiDS+GAMA: Cosmology constraints from a joint analysis of cosmic shear, galaxy-galaxy lensing and angular clustering
van Uitert, Joachimi, et al

Present cosmological parameter constraints from a joint analysis of 3 cosmological probes: the tomographic cosmic shear signal in ~450 deg2 of data from KiDS, the galaxy-mater cross-correlation signal of galaxies from GAMA determined with KiDS WL, and the angular correlation function of the same GAMA galaxies.  Use fast power spectrum estimators that are based on simple integrals over the real-space correlation functions, and show that they are unbiased over relevant angular frequency ranges.  Test the full pipeline on numerical sims that are tailored to KiDS and retrieve the input cosmology.  By fitting different combinations of PS, demonstrate that the 3 probes are internally consistent.  For all probes combined, obtain S8=sigma8 x sort(Omega_m/0.3) = 0.801±0.032, consistent with Planck and the fiducial KiDS-450 cosmic shear correlation function results.  The combination of probes results in a 21% reduction in uncertainties over using the cosmic shear power spectra alone.  The main gain from these additional probes comes through their constraining power on nuisance parameters, such as the galaxy IA or potential shifts in the redshift distributions, which are up to a factor of 2 better constrained compared to using cosmic shear alone, demonstrating the value of LSS probe combination.


1706.05133
Geometry and growth contributions to cosmic shear observables
Zorrilla Matilla, Hainan, Petri, Namikawa

Explore the sensitivity of WL observables to the expansion history of the universe and to the growth of cosmic structures, as well as the relative contribution of both effects to constraining cosmo parameters.  Utilize ray-tracing dark-matter-only N-body sims and validate the technique by comparing the results for the convergence PS with analytic results from past studies.  Then extend the analysis to non-Gaussian observables which cannot be easily treated analytically.  Study the convergence (equilateral) bispectrum and 2 topological observables, lensing peaks and Minkowski functionals, focusing on their sensitivity to the matter density Omega_m and the DE EoS w.  Find that a cancelation between the geometry and growth effects is a common feature for all observables, and exists at the map level.  It weakens the overall sensitivity by up to a factor of 3 and 1.5 for w and Omega_m, respectively, with the bispectrum worst affected.  However, combining geometry and growth information alleviates the degeneracy between Omega_m and w from either effect alone.  As a result, the magnitude of marginalized errors remain similar to those obtained from growth-only effects, but with the correlation between the 2 parameters switching sign.  These results shed light on the origin of cosmology-sensitivity of non-Gaussian statistics, and should be useful in optimizing combinations of observables.