We investigate the buildup of galaxies from various vantage points. The first two chapters focus on the stellar content of galaxies, especially the distribution of stellar masses at birth and potential variations therein in various galactic environments.

One of the key discoveries in exoplanet research over the past decade is the abundance of small planets in our Milky Way. Despite their high numbers, our understanding of their atmospheres remains limited, and it is unknown if they possess atmospheres at all.

Planets are formed in disks of gas and dust around young stars.

This thesis explores the theoretical and observational properties of distant massive galaxies that harbour active black holes in their centres and shine brightly at radio wavelengths.

In this thesis, we use low-frequency and high-frequency radio observations to address the following questions regarding quasars: is the radio loud/quiet quasar dichotomy real?

This thesis focuses on protoplanetary disks: flattened structures of gas and dust around young stars in which planets are expected to form and grow.

Supervisor: S.F. Portegies Zwart Co-Supervisor: A.G.A. Brown

De Nederlandse fysicus Jaap Kistemaker slaagde er in 1952 voor de eerste keer in om uranium te verrijken.

In this work, I explore the creation of new methods that optimize simulations of the gravitational N-body problem. Specifically, I take advantage of the recent popularity of Machine Learning methods to find tools that can suit this problem.

Promotor: W. Jaffe, Co-promotor: K. Meisenheimer

Promotores: Prof.dr. E.F. van Dishoeck, Prof.dr. C.P. Dullemond

Promotor: Jelle S. Kaastra Co-promotor: Jelle de Plaa

A dense region of a gaseous and dusty cloud collapses to form a protostar surrounded by a disk and an envelope. This thesis uses both observations and models to study physical and chemical conditions of these protostellar systems which are likely where planets start to form.

This thesis examines the link between simple molecules and the underlying structure and chemistry within protoplanetary disks - the birthplaces of planets.

Understanding the formation and evolution of planetary systems is one of the most fundamental challenges in astronomy. To directly image and study young exoplanets and the circumstellar disks they form from, dedicated high-contrast imaging instruments are built.

Promotor: Prof.dr. V. Icke, Co-Promotor: T.I. Madura

This thesis focus on the interaction between M dwarf stellar winds and Galactic cosmic rays and the possible effects on the habitability of exoplanets.

Pulsars were first discovered in 1967 and since then the population has grown and expanded over several wavelengths.

Promotores: Prof.dr. A.G.G.M. Tielens, Prof.dr. L. Kaper (UvA)

In this thesis, the research focuses on the properties of dark matter and dark matter haloes and how they connect with the galaxies we can observe in the Universe.

This thesis is a (biased) journey through very different topics in astrophysics: quasars and new populations of active galactic nuclei, gravitational waves from merging black holes, and protoplanetary discs around young stars.

To address the fundamental questions of how life on Earth emerged and how common life may be in the Universe, it is crucial to know the chemical composition of the planet-forming material.

Promotor: Prof.dr. E.F. van Dishoeck

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.

The formation and evolution of galaxies is fundamentally driven by the formation of new stars out of cold gas.

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.