Cosmology and Large Scale Structure

Cosmology is the science that studies the Universe as a physical entity and explores its overall properties, formation and evolution. During its very early stages, the Universe went through a phase of very rapid expansion (inflationary phase), which, among other things, created tiny initial fluctuations in the matter density field. Gravity caused these fluctuations to grow, which caused matter to pile up, forming stars, galaxies and clusters of galaxies. As a result, the universe is filled with a pattern, known as the Large Scale Structure of the Universe. This topic focuses on the processes that formed the structure we can observe today.

Kapteyn staff have long been interested in the fundamental structure of the Universe and the nature of dark matter.

We focus on the following topics:

• The nature of the initial conditions from which structure has evolved.
• The physical processes that govern the evolution of structure at each stage.
• The morphology and statistical properties of the Large Scale Structure of the Universe.
• The nature and amount of the dark matter and the dark energy.
• Detection of the influence of first stars and mini-quasars, i.e., the Epoch of Reionization (EoR) via HI.
• Modified Newtonian Dynamics as alternative to the Dark Matter hypothesis.

Many of these topics are tightly connected to the research theme Galaxy Structure, Formation and Evolution.

The selected projects and programs for the Kapteyn Institute in this field are the search of HI 21-cm emission from the EoR with LOFAR as well as theoretical studies of the processes during the EoR and Cosmic Dawn. Furthermore study of the Cosmic Web via theoretical studies as well as with APERTIF that will map 10⁵ HI sources in the nearby Universe. Joint research is being done on the early-universe and inflationary physics with the institute of theoretical physics.

Future directions in the field of cosmology and large structure for the Kapteyn Institute involve the detection of HI from the EoR with LOFAR and subsequently extension of this program to the Cosmic Dawn with the square kilometer array (SKA), as well as tomography of the EoR. Furthermore there will be a small involvement in cosmic microwave background experiments in connection with theoretical physics.

Scientific staff working in this field are Dayal, Koopmans, Wang, van de Weijgaert and Zaroubi