Weak lensing probes of primordial non-Gaussianity and mass estimators of weak-lensing clusters

• Applicant: Laura Marian, Ph.D.
• Subject Area: Astrophysics and Astronomy
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 170603556

Weak gravitational lensing (WL) is one of the prime tools to determine the cosmological parameters describing the universe. In particular, it can measure the equation of state of Dark Energy, and it can also be used to test General Relativity. This proposal suggests two lines of investigation, particularly useful in view of the short- and long-term upcoming lensing surveys. The first line addresses the potential of WL surveys to measure primordial non-Gaussianity. We shall use the Fisher matrix formalism to establish which WL observables are suited for this task. These observables will then be measured in shear maps obtained by ray-tracing through numerical simulations of structure formation. The simulations are ‘state-of-the-art’ and have been evolved with both Gaussian and non-Gaussian initial conditions. Thus, it will be possible to probe numerically the sensitivity of WL observables to primordial non-Gaussianity. Among the observables that will be tested and combined are shear peaks, the shear power spectrum, and the shear bispectrum. This study is innovative on several counts, and should yield results that will be useful for future surveys.The second line of research is a full exploration of the cosmological information carried by shear peaks. The 2- and 3-point correlation functions of the shear peaks, as well as the cross-correlation of shear peaks and the shear field have not yet been explored for cosmological constraints. We shall study them both theoretically and in WL maps, and we shall also assess their sensitivity to primordial non-Gaussianity. The other major goal is to give a theoretical prediction for the shear-peak function, also backed up by numerical measurements.

• DFG Programme: Research Grants