The theoretical explanation of cosmic acceleration is nowadays one of the biggest puzzles in cosmology.

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

It must be there. We just cannot see it: mysterious dark matter and dark energy in the universe. Henk Hoekstra is one of the many cosmologists who would love to know what exactly these substances consist of. He has received a European research grant of 1.3 euro million to find out.

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”.

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

Promotor: A. Achúcarro Co-promotor: A. Boyarsky

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.

Dark matter. Something invisible that, according to calculations, comprises about 85% of the matter in the universe. With an ERC Advanced Grant of €2.5 million, Professor of Observational Cosmology Henk Hoekstra will map out even more precisely where this dark matter is to be found.

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 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 book provides the answers, presenting clear insights into the current state of affairs and exploring future prospects.

It is an established fact that the Standard Model has to be extended to explain the so-called Beyond the Standard Model (BSM) phenomena: dark matter, matter-antimatter asymmetry of the Universe and neutrino flavour oscillations.

The focus of the dissertation

Leiden University is in the process of transitioning from one energy source to another: fossil fuels have to make way for sustainable energy from sunlight, water and wind.

This thesis is largely an experimental study on the formation of solid-state simple and complex organic molecules in the H2O-rich and CO-rich ice phases of dense interstellar clouds and dark cores.

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

Twenty years from now, the world population is estimated to be around 8.7 billion people, compared to the current 7.3 billion. In combination with the improvements in living standards and the corresponding growth in consumption, this will result in an enormous increase in the demand for food, consumables,…

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

The transition to new and renewable energy sources should be completed by 2050. Researchers in various disciplines at Leiden University are conducting unique research that will help us make this transition and reduce CO2 emissions.

For Leiden University’s operations, sustainability is an important topic, especially looking at the CO2-footprint, renewable energy and the greening of buildings.

The energy system is at the heart of two of the greatest challenges of the 21st century: decreasing CO2 emissions to meet the ambitions of the Paris agreement while fulfilling the growing energy demand associated with the economic aspirations of a growing world population.

In this project, we use social network analysis to analyze the behavior of users in online forums and associated marketplaces over time.

The energy transition is a complex transformation process that is not only about technology -moving towards renewable energy sources-, but even more so about societal and institutional change. The energy transition requires and provides opportunities for actors to take on new roles.

The Institute of Environmental Sciences has carried out and participates in several projects that deal with the analysis of energy systems.

Energy transition will entail the construction of large numbers of new energy installations. Such construction projects may meet with opposition from people living close by. Assistant Professor Bríd Walsh investigated how the local community can best take part in such projects.

An international team of astronomers has found an unexpected link between dark matter and visible stars in stellar systems. This discovery may even cause us to reconsider our understanding of gravity. They published on their discovery in 'Nature' on 1 October.

We would like to present to you a simple guidebook about living a sustainable life as a student in the cities of Leiden and The Hague. Whether you are a first-year student still trying to find your way around or already doing your masters – students wanting to explore more sustainable options and save…

Promotor: Huub de Groot, Co-promotor: Francesco Buda

An international team of astronomers, including Professor Koen Kuijken, has published a series of online articles presenting the first results of a major search for dark matter. Never before have researchers been able to chart so precisely the characteristics of groups of galaxies and their dark matter.…

Marc Koper’s research focuses on electrocatalysis and electrochemical surface science for sustainable energy and chemistry. Reactions of interest are the redox reactions of the oxygen/hydrogen cycle (water oxidation, hydrogen evolution), the carbon cycle (reduction of carbon dioxide, oxidation of small…

Twenty years from now, the world population is estimated to be around 9 billion people (now 8 billion). In combination with the improvements in living standards and the corresponding growth in consumption, this will result in an enormous increase in the demand for food, consumables, water and energy.…

Lecture

The transition from fossil fuels and the practical changes that this entails make many demands on citizens. Emma ter Mors, a psychologist and lecturer at Leiden University, is researching the factors that contribute to public perception and acceptance of new energy technologies.

How can you see something that’s invisible? Well, with Euclid! This future ESA telescope will map the structure of the Universe and teach us more about invisible dark matter and dark energy. Scientific coordinator of Euclid and Leiden astronomer Henk Hoekstra explains how this works.

Examining if large scale application of new energy pathways can be constrained by materials and emissions.

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.

Hetterscheid

On Sunday night 25 September, all the lights in Leiden will switch off and we will see the starry sky above us twinkling in all its glory. A unique opportunity for all residents of Leiden to experience the vastness of the cosmos and view the impressive artwork that hangs over our heads every night.…

Chemical reactions go hand-in-hand with an energy exchange with the environment in which they take place. Surfaces offer a variety of energy dissipation channels, constituted by the nuclear and electronic degrees of freedom of the atoms at the interface. Aiming at an improved future harvesting of energy,…

Cosmologists can measure with increasing precision how the universe is expanding and changing. This is producing unexpected results and causing cracks in our picture of the universe. At the ESOF session The Dark Side of our Mysterious Universe, cosmologists, astronomers and philosophers will discuss…

In comparing a selection of 18th-century histories to a representative sample of 19th-century histories of science, this project inquires: Which early modern vices persisted into the 19th century and to what extent were those vices embodied in anecdotes, conveyed through commonplaces, or symbolically…

The main research theme in the group of Dennis Hetterscheid is to understand and mimic bioinorganic multi-electron processes that are relevant to our future energy infrastructure. Reduction of protons generates hydrogen that can be used as a chemical fuel. Alternatively to gaseous hydrogen, the reduction…

Researchers at Leiden Observatory study the fundamental physics that creates structure in the Universe. These processes collect matter into galaxies and gas into stars. With the use of powerful telescopes and advanced calculations and computer simulations, Leiden astronomers seek to understand the origin,…

Researchers at Leiden Observatory study the fundamental physics that creates structure in the Universe. These processes collect matter into galaxies and gas into stars. With the use of powerful telescopes and advanced calculations and computer simulations, Leiden astronomers seek to understand the origin,…

Material circularity and energy efficiency are highly relevant and intertwined issues for the transition towards a carbon-neutral and circular built environment. In the Netherlands, the building sector has been rendered a priority towards a circular and low-carbon society.

Over the past century, the world population has grown exponentially, as has our need for energy and raw materials. If we wish to continue to live prosperously in the future, we have to radically restructure our economy and consumption. Scientific research shows us how to do this.

Over the past century, the world population has grown exponentially, as has our need for energy and raw materials. If we wish to continue to live prosperously in the future, we have to radically restructure our economy and consumption. Scientific research shows us how to do this.

What are the 'dark' components of the universe?