One of the most important correlation functions in physics, especially in cosmology, is the energy density, which describes how much energy is present at each point in spacetime due to matter fields. A key contribution to the energy density of the primordial universe comes from gravitational waves (GWs),…

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

The first direct detection of gravitational waves opened the possibility of mapping the Universe via this new and independent messenger.

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.

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

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.

In this thesis we study the landscape of gravitational models which modify GR by introducing an additional scalar degree of freedom (d.o.f.) to source Cosmic Acceleration.

In astronomy, the interpration of observations and measurements plays a crucial role: we rely purely and fundamentally on the information that reaches us as observers. And 80% of all matter in the universe is undetectable directly.

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

Learning about My meaningful Way through life and profession.

Leiden My Way is een co-curriculair persoonlijk ontwikkelprogramma uitgevoerd aan de Faculteit der Sociale Wetenschappen.

Promotor: Prof.dr. M. de Jong

The Sun and all the stars in the night sky reside in the Milky Way galaxy. In the at-rest reference frame of the Galaxy, typical stars travel with velocities of about 100-200 kilometres per second.

Promotor: P. T. de Zeeuw, Co-promotor: N. Neumayer; G. van de Ven

Op 29 april 2020 verdedigde Beth Van Schaack haar proefschrift 'Imagining Justice for Syria: Water Always Finds Its Way'. Het promotieonderzoek is begeleid door promotor prof.dr. C. Stahn.

Promotor: K.H. Kuijken

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

Three major cosmology-focused missions are planned for the next decade: the Euclid space telescope, the Vera C. Rubin Observatory in Chile, and the Nancy Grace Roman Space Telescope.

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.

Do sustainability values play a role in motivating people to act for biodiversity in successful projects and in successful leadership action? And how could these values be incorporated in current economic valuation methods?

Promotor: Prof.dr. A.G.G.M. Tielens

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

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.

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.

A brief review essay on some of the work that has been recently published in the emergent field of digital ethnography.

The ultimate goal of cosmologists is to find a cosmological model able to explain the current observational data.

Promotor: Koen Kuijken Co-promotor: Henk Hoekstra

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.

Galaxies form and live inside dark matter haloes. As a consequence, they are exposed to the tidal fields generated by the surrounding matter distribution: this imprints a preferential direction to the galaxy shapes, which leads to a coherent alignment on physically close galaxies, called intrinsic a…

The formation of stars and planets happens over multiple scales, which can interact. In particular, planet formation happens in the dense, complex environment of star forming regions.

Promotor: Prof.dr. J. Schaye, Co-promotor: Marcello Cacciato

This thesis investigates the structural evolution and assembly of galaxies since the first few billions years after the big bang.

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-…

Improvements of weak gravitational lensing shape measurements are presented and some used for data analysis.

Valetudo, zo hebben de astronomen het nieuw ontdekte Jupitermaantje genoemd. Het is een weerbarstig exemplaar dat dwars tegen haar soortgenoten in beweegt. In de Volkskrant reageert Leidse astronoom Simon Portegies Zwart op de bijzondere ontdekking.

What physics controls the properties of quantum matter, such as how electrons flow inside high-temperature superconductors? This question has captivated the physics community and industry for decades, in part due to the great technological potential such materials have, but also because they have resisted…

This thesis is dedicated to the exploration of the primordial dark ages: unknown physics during the earliest stages of the Universe’s expansion that have not yet been directly probed by observations. Cosmic inflation is a burst of exponential expansion of space after the “Big Bang”.

Op deze pagina kunt u promoties van onderzoekers van de Universiteit Leiden live volgen via streaming video.

De meeste Learning My Way-modules hebben een vergelijkbare structuur: voorbereiding, seminar, integratie.

If mankind wants to survive into the 22nd century, we will need to change the way we live drastically. The human impact on our planet is everywhere, we are changing the atmosphere, the oceans and the land, leading to global warming, climate change, loss of biodiversity and pervasive pollution. There…

De Learning My Way-methodologie is afgelopen 10 jaar ontwikkeld en geperfectioneerd. Begonnen in experimentele vorm in het FSW Honours College, is LMW al snel door verschillende instellingen opgepakt in opleidingen en voor HRM-doeleinden.

In samenwerking met Rijksmuseum Boerhaave, naar aanleiding van de tijdelijke tentoonstelling 'Dichter bij het zwarte gat', te zien t/m 5 januari 2025.

The focus of the dissertation

Wat is de invloed van de Internationale Verdragen ICCPR en ICESCR? Hoe kan hun toekomstige rol in de bescherming van de mensenrechten verder worden verbeterd? Dit is een kleine greep uit de vragen die worden gesteld tijdens de conferentie ter ere van de 50ste verjaardag van het ICCPR en ICESCR.

This PhD thesis concerns the topic of arithmetic geometry. We address three different questions and each of the questions in some way is about counting how big some set is or can be.

Learning My Way wordt gebruikt in een breed scala aan onderwijscontexten. Daarbij wordt altijd een blended learning en flipped classroom-benadering toegepast om optimale integratie van persoonlijke inzichten in dagelijks leven en gedrag mogelijk te maken.

Promotores: G.R. de Snoo, W.T. de Groot, Co-promotor: C.J.M. Musters