Die Korrelation zwischen der Materieverteilung und den Galaxien im Universe: Untersuchung im Rahmen des Kilo Degree Surveys (KiDS)

• Antragsteller: Professor Dr. Peter Schneider
• Fachliche Zuordnung: Astrophysik und Astronomie
• Förderung: Förderung von 2015 bis 2021
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 269979046

• Erstellungsjahr: 2022

Zusammenfassung der Projektergebnisse

In the framework of this project, technical and scientific aspects of the weak gravitational lensing effect were investigated. As a first central point, we combined the optical data of our Kilo-Degree Survey KiDS with corresponding near-infrared data from the VIKING survey that covered the same sky area. In this way, we generated a unique dataset which is of enormous importance for weak lensing studies, in particular regarding the selection of sources in weak lensing applications and the estimation of their redshift distribution via photometric redshifts. The second component of this project concerned scientific applications of this dataset and the development of corresponding analysis methods. Employing the weak lensing effect, we studied the relation of the distribution of galaxies in the Universe, relative to the corresponding underlying mass distribution; we also investigated how this relation depends on the properties of the galaxy population. For that purpose, we developed different methodological tool that we thoroughly tested on cosmological simulations. From these test, we identified and quantified a systematic effect (magnification effect), which has hardly been studied in this connection. We were able to develop a way how to correct for this effect in the analysis. We developed a method for measuring the relation between pairs of galaxies and the underlying matter distribution, which yields a very substantial improvement over previous methods. Employing this new code, we were able to compare the measured correlations from the aforementioned KiDS dataset with that of two different models for the formation and evolution of galaxies. This comparison then showed that one of the two models describes the result from observations very well, whereas the second model can be safely excluded with our data, at high statistical significance. The methodological aspects of this project will be of great interest for the future surveys of the ‘fourth generation’, like Euclid and Rubin/LSST. Several members of our group have become members of the Euclid Consortium and in the LSST/DESC collaboration. In particular, the activities in the framework of this DFG project have substantially contributed to our current and future role in the ESA satellite project Euclid, which will be launched in 2023 and which promises a enormous step for all aspects of cosmology (and beyond), in particular regarding dark energy and dark matter.

Projektbezogene Publikationen (Auswahl)

• 2016, “RCSLenS: A new estimator for large-scale galaxy-matter correlations”, MNRAS 456, 3886–3898
  Buddendiek, A., Schneider, P., Hildebrandt, H., Blake, C., Choi, A., Erben, T., Heymans, C., van Waerbeke, L., Viola, M., Harnois-Deraps, J., Koens, L. & Nakajima, R.
  
• 2018, “Unveiling galaxy bias via the halo model, KiDS and GAMA”, MNRAS 479, 1240–1259
  Dvornik, A., Hoekstra, H., Kuijken, K., Schneider, P., et al.
  
• 2019, “KiDS+VIKING-450: A new combined optical and near-infrared dataset for cosmology and astrophysics”, A&A 632, A34 (17 pages)
  Wright, A.H., Hildebrandt, H., Kuijken, K., et al. (incl. P. Schneider)
  
• 2019, “Magnification bias in the shear-ratio test: a viable mitigation strategy”, A&A 623, A94 (9 pages)
  Unruh, S., Schneider, P. & Hilbert, S.
  
• 2020, “An adapted filter function for density split statistics in weak lensing”, A&A 642, A161 (12 pages)
  Burger, P., Schneider, P., Demchenko, V., Harnois-Déraps, J., Heymans, C., Hildebrandt, H. & Unruh, S.
  
• 2020, “Measuring galaxy-galaxy-galaxy-lensing with higher precision and accuracy”, A&A 634, A13 (14 pages)
  Linke, L., Simon, P., Schneider, P. & Hilbert, S.
  
• 2020, “The effects of varying depth in cosmic shear surveys”, A&A 634, A104 (16 pages)
  Heydenreich, S., Schneider, P., Hildebrandt, H., Asgari, M., Heymans, C., Joachimi, B., Kuijken, K., Lin, C.-A., Tröster, T. & van den Busch, J.L.
  
• 2020, “The importance of magnification effects in galaxy-galaxy lensing”, A&A 638, A96 (15 pages)
  Unruh, S., Schneider, P., Hilbert, S., Simon, P., Martin, S. & Corella Puertas, J.