1604.07821
Cosmic visions dark energy: technology
Donelson et al
A strong instrumentation and detector R&D program has enabled the current generation of cosmic frontier surveys. A small investment in R&D will continue to pay dividends and enable new probes to investigate the accelerated expansion of the universe. Instrumentation and detector R&D provide critical training opportunities for future generations of experimentalist, skills that are important across the entire Department of Energy High Energy Physics program.
1604.07836
A new method to break the mass sheet degeneracy using aperture moments
Rexroth, Natarajan, Kneib
Mass determinations from GL shear and the higher order estimator flexion are both subject to the mass sheet degeneracy. Mass sheet degeneracy refers to the ambiguity that arises due to the fact that the addition of a constant surface mass density sheet does not alter the lensing observables. Propose a new technique to break the mass sheet degeneracy. The method uses mass moments of the shear or flexion fields in combination with convergence information derived from number counts which exploit the magnification bias. The difference between the measured mass moments provides an estimator for the magnitude of the additive constant that is the mass-sheet. For demonstrating this, derive relations that hold true in general for n-th order moments and show how they can be employed effectively to break the degeneracy. Investigate the detectability of this degeneracy parameter from the method and find that the degeneracy parameter can be feasibly determined from stacked galaxy-galaxy lensing data and cluster lensing data. Furthermore, compare the S/N ratios of convergence information from number counts with shear and flexion for SIS and NFW models. Find that the combination of shear and flexion performs best on galaxy and cluster scales and the convergence information can therefore be used to break the mass sheet degeneracy without quality loss in the mass reconstruction. In summary, there is power in the combination of shear, flexion, convergence and their higher order moments. With the anticipated wealth of lensing data from upcoming and future satellite missions - EUCLID and WFIRST - this technique will be feasible.
1604.07871
Cosmology from large scale galaxy clustering and galaxy-galaxy lensing with Dark Energy Survey Science Verification data
Kwan, et al
Present cosmo constraints from DES using combined analysis of angular clustering of red galaxies and their ross-correlation with WL of background galaxies. Use a 139 sq deg contiguous patch of DES data from SV period of observations. Using large scale measurements, constrain the matter density of the Universe as Omega_m=0.31±0.09 and the clustering amplitude of the matter power spectrum as sigma_8=0.74±0.13 after marginalizing over 7 nuisance parameters and three additional cosmo parameters. This translates into S_*=sigma_8(Omega_m/0.3)^0.16 = 0.74±0.12 for the fiducial lens redshift bin at 0.35<z<0.5, while S_*=0.78±0.09 using two bins over the range 0.2<z<0.5. Study the robustness of the results under changes in the data vectors, modeling and systematic treatment, including photometric redshift and shear calibration uncertainties, and find consistency in the derived cosmo parameters. Show that the results are consistent with previous cosmo analyses from DES and other data sets and conclude with a joint analysis of DES angular clustering and gg lensing with Planck CMB data, BAO and SNIa measurements.
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