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.

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.

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

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…

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

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.

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.

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.

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Promotor: Koen Kuijken Co-promotor: Henk Hoekstra

The institute is funded by the Ministries of Education, Culture and Science and of Foreign Affairs and by Leiden University. To safeguard the institute’s independence and interests in Morocco, it is part of the Netherlands Embassy in Rabat under Moroccan law. The institute performs its tasks under the…

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.

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

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

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

The unemployment replacement rate data set, assembled by Olaf Van Vliet & Koen Caminada (version 1, January 2012), provides data on unemployment benefit schemes in 34 welfare states from the 1970s until 2009. The current data set includes all 27 member states of the European Union and 7 non-EU OECD…

In the late 19th and early 20th century, hundreds of thousands of Chinese labor migrants crossed the seas to the Dutch East Indies. On the tobacco plantations of northeastern Sumatra and in the tin mines of Bangka and Belitung, they endured long hours and harsh conditions. Their journeys formed part…

Tuberculosis is a major global health problem caused by the Mycobacterium tuberculosis complex, claiming more than a million lives annually.

We are a dynamic research group at the Leiden Institute of Physics. Our aim is to explore and understand quantum materials, including strange metals, high-temperature superconductors, and quantum critical electron matter.

We are interested in understanding the mechanics of soft materials, of which biological materials are prominent examples.

The Graduate School of Governance and Global Affairs offers PhD programmes that address the pressing societal challenges of our time.

The Faculty of Governance and Global Affairs is one of a total of seven faculties of Leiden University, located in The Hague.

Leiden University Centre for the Arts in Society (LUCAS) is dedicated to ground-breaking and interdisciplinary research dealing with the relations between culture and society.

SOLID: Solidarity under strain - A legal, criminological and economic analysis of welfare states and free movement in the EU. Analysing the ways in which immigration structurally challenges and changes the organization and conceptual boundaries of national welfare states.

The Austrian Studies Fund supports the Special Chair for Central European Studies, invites visiting professors from Austria and connects with Austria Centres over the world.

Are you a PhD or postdoc at the Leiden Institute of Chemistry? Join our community to amplify your voice, grow professionally, and build lasting connections within our institute.

Cooperation on education with China stimulates innovation and brings a different perspective and new content to classrooms.

Recent welfare reforms in the Netherlands show a trend of reducing welfare accessibility and increasing obligations. Although the effects thereof on directly-targeted economic outcomes, such as welfare dependency and labor participation, are often assessed, potential spillovers to other economic and…

The consequences of social tendencies for the legislation and institutions in the fields of social security, the labor market policy and pension reform are examined in this multdisciplinary research program..

Analysing the ways in which immigration structurally challenges and changes the organization and conceptual boundaries of national welfare states.

LION offers a PhD program in which candidates carry out independent research on a specific topic, culminating in a PhD thesis.

What would a university be without its students? In 2025, we will celebrate 450 years of studying with an exhibition showcasing our students from the past centuries. How did they study in the past? And how do they study now? This outdoor exhibition will be on display from 23 April at the Hortus bota…

Papyrology+, founded in 2014, is a collaboration of Leiden scholars studying (Abnormal) Hieratic, Demotic, Aramaic, Greek, Latin, Coptic, and Arabic papyri from a socio-historical, economic and linguistic perspective. Papyrology+ aims to explore new opportunities and directions in the study of ancient…

In 2017, at the start of the Rutte III cabinet, tax scholars Leo Stevens and Koen Caminada presented a blueprint for a new tax system. Today, four years on, they observe that the cabinet has put little effort into innovations in the area of tax.

Een uitbreiding van de NIMAR collectie van de Universitaire bibliotheken Leiden.

The celebration of the university’s 450th anniversary is not confined to the walls of the university. For the 7th time, professors stood in front of the class of grade 7, in both Leiden and The Hague. Four FGGA professors visited primary schools, introducing the children to research questions such as…

Astronomer Koen Kuijken and physicist Tjerk Oosterkamp have each been awarded a major subsidy by NWO. The funding will allow them to construct new research facilities.

Are you in need of some rest, stressed about an exam, or feeling under the weather? Since a few months you can find Mindfulnest at the Science Faculty. Assessor Ava Bauer and student psychologists Petra Penning and Koen Linders explain what the Mindfulnest can mean for you.

During the Faculty of Science New Year's reception, Daniël Rozen was named Discoverer of the year 2015. Nienke van der Marel and Koen van der Maaden both won the prize for the best dissertation and Jeroen van Smeden was named Best Teacher of 2015.

Overview of the main research projects at the Leiden Papyrological Institute.

Koen Bastiaans and his colleagues discovered a new quantum liquid unlike anything ever seen. They did it by using a technique that can be compared to listening to the sound of raindrops falling on a roof. Publication in Science 29 October.

Data from 41 million galaxies does not shake up the standard cosmological model after all. To that conclusion, to their own surprise, comes an international team of researchers including Koen Kuijken, professor at the Leiden Observatory.

At the beginning of this year CADS Lecturer Koen Suidgeest published his photobook Why I Cry on Airplanes. In this book he takes you on a visual flight around the globe to meet resilient human beings who live under challenging conditions. He decided to use the changing situation that COVID-19 causes…

Why are morpho butterflies blue? That is what high school students Frederique Kerstens and Koen van Griensven investigated in their high school profile paper at the Leiden Institute for Research in Physics. In doing so, they won the KHMW Profielwerkstukprijs 2023. ‘We didn't expect it, but are of course…

On Thursday 28 September, the Committee on Social Minimum, of which Koen Caminada is a member, presented its second report to outgoing minister for poverty policy in the Netherlands, Carola Schouten. The Committee was established by the minister at the request of the House of Representatives.

Dirk Uittenbogaard, a student on the Delft-Leiden Master’s in Industrial Ecology, has won a gold medal for rowing at the Olympic Games in Tokyo. Uittenbogaard took gold in the men’s quadruple sculls, together with Abe Wiersma, Tone Wieten and Koen Metsemakers.