Promotor: F.P. Israel, Co-Promoter: R. Meijerink

Covid-19 is een disruptieve ontwikkeling die hier en nu veel vraagt van zorgprofessionals, bestuurders en managers. Hoewel de crisis nog volop bezig is, is nu al duidelijk dat het Coronavirus een blijvende impact zal hebben op zorginstellingen en fundamentele vragen oproept over hoe we onze zorg optimaal…

Promotor: H.J.A. Röttgering, Co-promotor: G.K. Miley

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

On the largest scale, the Universe resembles a cosmic spiderweb. Most galaxies coexist in small groups within the threads of this web. At the nodes of the threads are enormous groups of galaxies forming the largest structures in the universe still held together by gravity: clusters of galaxies.

In this thesis, I study the formation of large-scale structure and the physics of particle acceleration at large scales (~Mpc).

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,…

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.

This thesis aims to enhance our understanding of galaxies by testing theoretical models of galaxy formation against observations, particularly in the cases of extreme systems which have been found to have an excess of baryonic mass in their central regions, in the form of either supermassive black holes…

The shock wave triggered by one of the five galaxies making up the iconic Stephan’s Quintet appears to be less disruptive than previously thought, with the shock likely being cushioned by dust particles in the surrounding gas. This is according to the analysis of the first scientific observations of…

Rossi

In this thesis, I studied the origin and evolution of the non-thermal radiation in merging galaxy clusters.

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

For the first time, astronomers have observed in three dimensions that gas from spiral galaxies is blown upwards and downwards at high speed, far out of the galaxy. They thereby confirm the theory of galaxy evolution: that star-forming galaxies create intergalactic gas flows by discharging gas along…

This paper critically compares seven widely used risk assessment tools for violent extremism, including the VERA-2R, the ERG 22+, the SQAT, the IR46, the RRAP, the Radar, and the VAF.

A number of scholars joint forces to analyse and re-analyse a number of Merovingian cemeteries and publish the results in the series Merovingian Archaeology in the Low Countries published by Habelt Verlag in Bonn (Germany). We call it the ANASTASIS project. This is the third volume in which the data…

In this thesis, we present new laboratory data of interstellar dust analogues.

Galaxies are often found in clusters, which contain many “red and dead” members that stopped forming stars in the distant past. Now, an international team of astronomers, led by Andra Stroe of Leiden Observatory and David Sobral of Leiden and the University of Lisbon, has discovered that these comatose…

Hot astrophysical plasma is ubiquitous in the Universe, from comets in our Solar system to the largest scale structures -- the cosmic web filaments. These hot plasmas, with the temperature of a few millions of degrees, are often observed in the X-ray wavelength range.

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.

When galaxies collide, do the black holes at their centre form a supersized black hole? This is what we think happens, but it's not as simple as that, according to Simon Portegies Zwart. Zwart, computer scientist and astronomer, has been awarded a VICI grant to research this phenomenon.

Galaxies in the Universe are distributed along the intricate framework of the Cosmic Web. Groups and clusters of galaxies comprise the densest regions in this network, and therefore, are excellent cosmic laboratories to study different aspects of galaxy evolution in extreme environments.

In 2015, Jorryt Matthee thought he discovered an extremely distant galaxy called CR7, which lacked elements heavier than helium. Three years later, he shows with measurements using the ALMA telescope that the galaxy does have carbon after all, and even in normal concentrations. The American Astronomical…

A galaxy is already incredibly large, but it can get even bigger. Astronomer Reinout van Weeren investigates clusters of galaxies, one of the largest structures in the universe. For his research into the origins and evolution of these clusters, he obtained an ERC Starting Grant of 1.5 million euros.…

A team of Leiden astronomers used the latest set of data from ESA’s Gaia mission to look for high-velocity stars being kicked out of the Milky Way, but were surprised to find stars instead sprinting inwards – perhaps from another galaxy.

Using the MUSE instrument on ESO’s Very Large Telescope in Chile, an international team of scientists, including many Leiden astronomers, have conducted the deepest spectroscopic survey ever. They focused on the Hubble Ultra Deep Field, measuring distances and properties of 1600 very faint galaxies…

An international team of astronomers that includes researchers from Leiden has discovered the most distant galaxy yet. The galaxy, called EGS8p7, is 13.23 billion light years away from Earth and already existed when the universe was only 550 million years old.

Astronomers led by Pieter van Dokkum have discovered a galaxy that barely contains any dark matter, which actually proves that dark matter does indeed exist. The research results will be published this week in Nature.

An international team of astronomers, including Leiden's Maciej Bilicki, has discovered an enormous supercluster of galaxies. The supercluster had previously been overlooked because it was obscured by our own Milky Way. The researchers are publishing their findings in the Monthly Notices of the Royal…

Dark matter represents around eighty per cent of the total mass in the Universe. Yet, we still don't really know what it's made of. Astronomer Pavel Mancera Piña is looking for answers. With a Veni grant from NWO and the most advanced telescopes, such as the James Webb Space Telescope, he will investigate…

Chemist Irene Groot has been awarded a TA grant. Together with Shell, Leiden Probe Microscopy, DSM Resolve and Utrecht University, Groot will conduct research into catalysts for the production of raw materials and fuels.

Dwarf satellite galaxies in the Milky Way perform different dances than researchers initially expected. Marius Cautun from Durham University received a Marie Curie grant to unravel the mysteries of this orbital dance. October 1st 2018 he will start his research at the Leiden Observatory.

Promotor: H.J.A. Rottgering, Co-Promotor: R.J. van Weeren

One of the key quests in astronomy is to study the growth and evolution of galaxies across cosmic time. Radio observations provide a powerful means of studying the formation of stars and subsequent buildup of distant galaxies, in a way that is unbiased by the presence of dust.

After almost twenty years the record for the most distant radio galaxy has been broken. A team of astronomers led by Leiden PhD candidate Aayush Saxena has discovered a radio galaxy from the time when the universe was just one billion years old. The galaxy is at a distance of 12 billion light years…

An international team of astronomers, with researchers at Leiden Observatory playing a leading role, has mapped the fuel for galaxy formation in the iconic Hubble Ultra Deep Field. The results of the research have been accepted for publication in The Astrophysical Journal.

By a stroke of luck, a team led by Dutch PhD student Martijn Oei has discovered a radio galaxy of at least 16 million lightyears long. The pair of plasma plumes is the largest structure made by a galaxy known thus far. The finding disproves some long-kept hypotheses about the growth of radio galaxie…

In a promotional video for the SUNRISE initiative, prof. Huub de Groot explains the impact and ideas behind artificial photosynthesis.

In 2018, astronomer Jorryt Matthee won the C.J. Kok Jury Prize for the best dissertation of the Faculty of Science. He succeeded in finding a number of rare galaxies from the early Universe. One of them received the same initials as football player Cristiano Ronaldo: CR7.

Within the field of astronomy, understanding how galaxies grow and evolve from the Big Bang to the present day is a challenging and complex question.

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

Promotor: K.H. Kuijken

Leiden scientists are the main applicants for five projects that have been awarded a Science Groot grant of up to 3 million euros in the Science Domain. In addition, several Leiden scientists are involved in other projects that have been awarded funding.

The largest galaxies in the Universe feed off cosmic oceans, which helps them grow. This is the presumption of an international team of scientist with two Leiden astronomers, based on observations of the ‘Spiderweb’ galaxy. The researchers published their evidence in Science on 2 December 2016.

Galaxies in the early universe are shrouded in a kind of mist: a cloud of hydrogen. With galaxies in the later universe this mist has disappeared. Astronomer Jorryt Matthee has made the first images of this dissipating mist. PhD defence 19 September.