One of the key limitations of the direct imaging of exoplanets at small angular separations are quasi-static speckles that originate from evolving non-common path aberrations (NCPA) to which the primary adaptive optics system is inherently blind. The main focus of this thesis is the development and…

The high velocity tail of the total velocity distribution of stars provides essential insight into fundamental properties of the Galaxy.

The physical origin of the dozens of stellar-mass binaries, the mergers of which have been detected by the LIGO-Virgo-KAGRA collaboration via gravitational waves, is still unknown.

“Temminck’s Order” is the scientific biography of Coenraad Jacob Temminck (1778–1850), a Dutch naturalist and the first director of ’s Rijks Museum van Natuurlijke Historie in Leiden.

Promotores: S.F. Portegies Zwart, E. M. Rossi

Promotor: Prof.dr. K.H. Kuijken, Co-Promotor: H.Hoekstra

In this thesis, I study the formation of large-scale structure and the physics of particle acceleration at large scales (~Mpc).

This thesis presents pioneering work on the panchromatic emission of some of the most luminous galaxies in the early Universe: star forming galaxies and active galactic nuclei.

Following the Big Bang, structure in the Universe started collapsing under the force of gravity. This resulted in the formation of the first stars, galaxies and clusters of galaxies.

Promotor: J.S. Kaastra Co-promotor: E. Constantini

Promotor: Koen Kuijken Co-promotor: Henk Hoekstra

One of the most important puzzles in modern astrophysics is the nature of dark matter.

Nowadays, it is well known that hydrogen and helium (and small traces of lithium and beryllium) were created shortly after the Big Bang, while the heavier elements are created in the cores of stars at different evolutionary stages. When these stars explode as supernovae, they expel metals synthesised…

Galaxy intrinsic alignments induce a major astrophysical contamination to weak gravitational lensing measurements and need to be modelled and mitigated when extracting cosmological information from such measurements.

Tracing the evolution of the molecular gas content in galaxies is critical for a complete understanding of galaxy formation and evolution, as it provides the direct fuel for star formation. Studies of high-redshift (z>1) molecular gas reservoirs, most commonly traced by carbon monoxide (CO), have seen…

It has now been well established that shocks and turbulent motions in the intra-cluster medium (ICM) generated through cluster mergers can produce large-scale synchrotron emission.

Promotores: F.H. van Lunteren, F.P. Israel

Promotor: I. A. G. Snellen, Co-promotor: M. A. Kenworthy

This thesis addresses the chemical processes that determine the compositions of giant planet atmospheres.

At the largest scales, two ingredients dictate the distribution of matter in the Universe. The first is dark matter, acting as an invisible scaffolding held together by gravitational forces.

Promotor: H.J.A. Röttgering, Co-promotor: M. Haverkorn

Organic molecules in interstellar space are important as they influence the structure of galaxies and star formations. Studying catalytic processes in space allows us to understand how molecular species are formed and chemically evolved in the interstellar medium and solar system objects.

This thesis focusses on the temperature structure in protoplanetary disks. The relation between structures seen in the dust and gas-phase molecules is investigated.

Promotor: Prof.dr. I.A.G. Snellen, C.U. Keller

Galaxies are environments where gas coalesces, cools, and is converted into stars. However, it remains unclear the exact mechanisms through which galaxies acquire, redistribute and lose their gas.

In this thesis we investigate cosmology and the large scale structure of the Universe using cosmological simulations.

The aromatic infrared bands (AIBs) seen throughout the interstellar medium (ISM) are generally thought to be carried by polycyclic aromatic hydrocarbons (PAHs) and their nitrogen analogues (PANHs).

Outflows are crucially important for the gas budget and evolution of luminous star-forming galaxies and AGNs, with observed mass outflow rates of the same order as the star formation rate. Greater star formation and black hole growth lead to more intense feedback and outflows, resulting in self-regulated…

Of all the mass in our Universe, 80% is thought to consist of a hypothetical and invisible substance called dark matter (DM).

For centuries astronomers studied the Universe by collecting light. Nowadays, we are living in times of great technological advancements, which allow us to explore our Universe in a new way - though gravitational wave radiation.

The radio sky harbours both galactic and extragalactic sources of arcminute- to degree-scale emission of various physical origins. To discover extragalactic diffuse emission in the Cosmic Web beyond galaxy clusters, one must image low–surface brightness structures amidst a sea of brighter compact fore-…

Promotor: Christoph U. Keller, Co-promotores: Matthew A. Kenworthy, Frans Snik

Dark matter is one of the biggest mysteries of the Universe. Its properties cannot be explained with the known laws of physics and elementary particles.

Multiple stars, that is two or more stars composing a gravitationally bound system, are common in the universe.

High-angular-resolution observations of the circumstellar material have uncovered numerous and very diverse substructures in protoplanetary discs, raising the question of whether they are caused by forming planets or other mechanisms.

Until the 1990s, the only known planets were those in our Solar System. Three decades later, several thousand exoplanets have been discovered orbiting stars other than the Sun, and substantial efforts have been made to explore these strange new worlds through spectroscopic analyses of their atmosphe…

Stars and planets form within cold, dense clouds of gas and dust drifting through interstellar space. Although dust makes up only a small fraction of this material, it plays a key role in shaping the chemical evolution of these environments.

Astronomical observations of cold regions in the universe show a rich inventory of ices. Part of these ices may end up on planets like our own, but in that journey they will be exposed to considerable amounts of radiation.

The field of exoplanet research is rapidly advancing through the development of new technology, observing techniques, and post-processing methods.

Promotor: Prof.dr. S.F. Portegies Zwart

A century ago, it was unclear whether the stars in the sky were clustered in groups, or widely spread in the universe.

Promotores: Prof.dr. G. Miley & Prof.dr. J.M. van den Broek

This research focuses on the distribution of chemical elements in protoplanetary disks, the birthplaces of planets. These disks form around young stars and contain gas and dust, from which planets grow. Ice plays a crucial role in planet formation, aiding the clumping of dust particles and influencing…

Promotor: F.P. Israel, Co-Promoter: R. Meijerink

We explored the Universe using weak gravitational lensing, a phenomenon that occurs when light from distant galaxies is bent by the gravitational fields of closer cosmic objects, much like how a lens distorts light.

On the largest scale, the Universe resembles a cosmic spiderweb. Most galaxies coexist in small groups within the threads of this web. At the nodes of the threads are enormous groups of galaxies forming the largest structures in the universe still held together by gravity: clusters of galaxies.

The work done during this PhD research, aims to investigate the effect of tidal heatingin the observability of extra-solar satellites around exoplanets.

Low-mass main-sequence stars like our Sun are continuous sources of outflowing hot magnetised plasma. In the case of the Sun, this is known as the solar wind, whereas for other stars they are called stellar winds.

Complex Organic Molecules (COMs) have been detected in objects across different stages of stellar evolution.

Stars like the sun are born in large molecular clouds existing from gas and dust. During the formation process, the chemical composition of the material can be altered drastically by the changing physical conditions.