The focus of the dissertation "Aspects of cosmic acceleration" is the study of possible mechanisms responsible for the late-time accelerated expansion of the universe.

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.

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.

Lecture

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

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.

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.…

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.

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.

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

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

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.

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

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

A stretchy sheet over a bowl representing space, a marble on it's surface creating a dimple, deforming space. Simple classroom experiments like these are featured in new educational videos by AstroEDU. In the videos Leiden astronomers Maria Cristina Fortuna and Henk Hoekstra explain what we know of…

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,…

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 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.

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.

We are cosmologists, in other words we use physics to study the Universe, how it started and evolved into the structure that we observe around us.

Research at Leiden Observatory spans the full width of modern astrophysical enquiry. It is based on observation, theory, simulation, and experiment. Two broad clusters characterize the ongoing research. Within each theme, researchers carry out their personal and specialized research programme. The two…

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,…

What are the 'dark' components of the universe?

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

Is our universe built up out of warm or cold dark matter? The standard model assumes cold dark matter particles, but astronomer Sylvia Ploeckinger is now testing the possibility of a warm counterpart: sterile neutrino’s. For this project, she received an NWO Physics/F grant, a special grant for women…

Leiden Observatory is going to use a new technique to carry out calculations on gravitational lensing measurements. They will do this is the context of research into the formation of elliptical galaxies. Alessandro Sonnenfeld (University of Tokyo) who developed this technique joined the research team…

Particle lab CERN gives the green light for the test phase of an experiment that aims to produce dark matter particles. Physicist Alexey Boyarsky is one of the initiators.

On Wednesday February 7th, Professor Ed Copeland from the University of Nottingham will give the Colloquium Ehrenfestii.

Exhibition

Unplugging equipment that's secretly guzzling electricity, putting the curtains behind the radiator and only using a water-saving showerhead. The students participating in the Student Energy Race are given tips that everyone who cares about the environment and their wallets should learn from.

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

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

A signal that is present both in the centre of our Milky Way and in distant places in the universe could reveal the origin of dark matter. This is what Leiden physicist Alexey Boyarsky concludes in an article in Physical Review Letters.

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.

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.

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,…

Astronomer Henk Hoekstra has been appointed Professor Observational Cosmology at the Leiden Observatory with effect from 1 August.

Leiden Observatory is the astronomical institute of the Faculty of Science of Leiden University.

Physicists at the Leiden Institute of Physics (LION) conduct fundamental research into physical phenomena. They are inspired by curiosity and the desire to know more about the world in which we live. This research has always paved the way for new practical applications. These are something that the…

The production of sustainable energy can take up to 1000 times more space than fossil fuels, environmental researcher Paul Behrens concludes in a publication in Energy Policy. Various media reported on this remarkable outcome.

Physicists at the Leiden Institute of Physics (LION) conduct fundamental research into physical phenomena. They are inspired by curiosity and the desire to know more about the world in which we live. This research has always paved the way for new practical applications. These are something that the…

Twenty years from now, the world population is estimated to be around 9 billion people (now 7.8 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.…

Climate change and energy transition were an important theme of the Dutch provincial elections: how should we invest in new sources of energy? Leiden University conducts multidisciplinary research into renewable energy solutions. Read more about this in the ‘Renewable Energy’ research dossier.

Astronomers want to understand the Universe, from the Big Bang to the present day, and what the future will hold. In Leiden they focus on two key questions: ‘How did stars and planets originate’ and ‘How were galaxies and black holes formed in the young Universe?’ A new generation of telescopes – just…

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.

Five Leiden astronomers tell about science in the podcast Astronomy et al. This podcast was set up by Ricardo Garcia Soto in September 2016 and is focused on anyone who is interested in science.

In the hunt for new particles, physicists look at ever higher energy particle collisions, moving the energy frontier. Some particles however are elusive not due to their high energy, but because they rarely interact. This raises a new barrier: the intensity frontier.