The third-order correlation functions of galaxy-galaxy lensing
Final Report Abstract
Galaxy-galaxy-galaxy lensing (G3L) is a relatively new probe for the study of the mattergalaxy connection inside the cosmic web. The focus of this project was on the lens-lens-shear correlation function that statistically quantifies the excess-mass of galaxy pairs within a common matter environment. Using data from the recent CFHTLenS, we measured this G3L signal for galaxy pairs with varying luminosity, stellar mass, and galaxy type; the measurements also comprised the related lens-shear-shear correlations which were not in the focus of this project. We were able to show that the excess-mass signal increases with luminosity and stellar mass, and that it is vanishingly small for spiral galaxies when compared to elliptical galaxies as predicted by our foregoing study using SAMs of galaxies. By emulating CFHTLenS-like stellar-mass samples with simulated data from the Millennium Simulation that has its dark-matter halo populated with SAM galaxies from models of the Durham and Garching group, respectively, we showed that both models can reproduce the relative trend with stellar mass. However, the Durham-type models overall predict a higher amplitude than in CFHTLenS and are in strong tension to the observations which suggests modifications to the model that reduce the relative number of satellite galaxies in high-mass halos. In an ongoing but soon finalized project, we test and describe an analytic model and its computer-code implementation for the excessmass. This project tests the consistency between second-order galaxy-galaxy lensing and G3L of a halo-model approach with the CFHTLenS measurements, and through GGL it produces physical parameters for the galaxies in the CFHTLenS samples used for G3L. It also uses the halo model to discuss excess-mass maps, giving a better qualitative understanding of this new diagnostic for the matter density around galaxy pairs. In an ongoing follow-up project, we are refining the measurement of excess-mass maps around lens galaxies in CFHTLenS aiming at an increased signal-to-noise ratio. These maps and their discussion in the context of our SAM predictions as well as the analytic model for G3L is planned to be published in 2017. Finally for a side-project, we elaborated on a technique for the compression of data that is useful for future analyses of G3L data. We demonstrated this technique in a cosmological application to third-order cosmic-shear correlations in CFHTLenS.
Publications
- 2012, “Galaxy-galaxy(-galaxy) lensing as a sensitive probe of galaxy evolution”, A&A, 547, A77 (11 pages)
Saghiha, H., Hilbert, S., Schneider, P., Simon, P.
(See online at https://doi.org/10.1051/0004-6361/201219358) - 2012, “The bispectrum covariance beyond Gaussianity. A log-normal approach”, A&A, 540, 9 (9 pages)
Martin, S., Schneider, P., Simon, P.
(See online at https://doi.org/10.1051/0004-6361/201118020) - 2012, “Towards an understanding of third-order galaxy-galaxy lensing”, A&A, 548, 102 (14 pages)
Simon, P., Schneider, P., Kübler, D.
(See online at https://doi.org/10.1051/0004-6361/201218993) - 2013, “CFHTLenS: higher order galaxy-mass correlations probed by galaxy-galaxy-galaxy lensing”, MNRAS, 430, 2476 (23 pages)
Simon P., Erben, T., Schneider, P., et al.
(See online at https://doi.org/10.1093/mnras/stt069) - 2015, “CFHTLenS: a Gaussian likelihood is a sufficient approximation for a cosmological analysis of third-order cosmic shear statistics”, MNRAS, 449, 1505 (21 pages)
Simon, P., Semboloni, E., van Waerbeke, L., et al.
(See online at https://doi.org/10.1093/mnras/stv339) - 2016, “Confronting semi-analytic galaxy models with galaxy-matter correlations observed by CFHTLenS” (9 pages)
Saghiha, H., Simon, P., Schneider, P., Hilbert, S.
