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

Promotor: Prof.dr. M. de Jong, Co-Promotor: Dr. A.J. Heijboer

The focus of the dissertation

What are the phylogenetic relationships among the members of speciation bursts?

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

In this work the reconstruction of a tau neutrino signal in the KM3NeT detector is discussed.

For the first time, scientists have traced back a high-energy neutrino to its source in space. It was produced by a so-called blazar—a supermassive black hole. Researchers from neutrino detector IceCube report this in Science. ‘This is a milestone for neutrino science,’ says physicist Dorothea Samtleben…

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

Promotor: Prof.dr. M. Franx, Co-Promotor: Rychard Bouwens

When a star gets too close to a supermassive black hole, it is torn apart by strong tidal forces in a tidal disruption event (TDE).

Physicists, including Dorothea Samtleben from Leiden University, are building a giant underwater telescope to unravel the origin of neutrinos and to solve the mystery surrounding dark matter. The first detector has now been installed. Once it is finished, the telescope will be three cubic kilometres…

Promotores: Prof.dr. M. Franx & Prof.dr. P.G. van Dokkum (Yale University)

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

An international team of astronomers from Leiden Observatory and others, has for the first time mapped a piece of the dark, cosmic web. The research strengthens the hypothesis that the young universe consisted of huge numbers of small groups of newly formed stars. The astronomers publish their findings…

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

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”.

Do natural soundscapes affect migratory decisions of fishes moving up and down rivers and is this process disturbed by vessel sounds?

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

This thesis consists of two subjects, that are both a consequence of radiation pressure.

Promotor: Prof.dr. A. Achucarro, Co-Promotor: J.W. van Holten

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.

A team of laboratory astrophysicists from Leiden University managed to make glycerol under conditions comparable to those in dark interstellar clouds. They allowed carbon monoxide ice to react with hydrogen atoms at minus 250 degrees Celsius. The researchers publish their findings in the Astrophysical…

This thesis revolves around the electronic spectroscopy of molecules in the laboratory and the search for the carriers of the diffuse interstellar bands (DIBs).

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…

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.

Promotor: M. de Jong, Co-Promotor: Samtleben

Promotor: Prof.dr. H.L.V. Linnartz

We explore the particle physics and quantum world at the time of the big bang.

Promotor: Prof.dr. M.K. Richardson, Co-Promotor: F. Witte

Sixty-four high school students from Slovenia, Czech Republic and The Netherlands have visited Leiden University in the week of 7-11 November, as part of the Talent Education Project. They split in eight groups, of which some went to the science faculty to conduct research projects.

PhD Defence

PhD Defence

This thesis contributes to studying primordial cosmology theories and their detectability in future observations.

Astronomical observations of cold regions in the universe show a rich inventory of ices. Part of these ices may end up on planets like our own, but in that journey they will be exposed to considerable amounts of radiation.

These are the proposed research projects for LEAPS 2019. Please note that not all projects will go ahead and some may still be added in the near future. Final funding decisions lie with the Faculty sponsors. And please make a note that if you are interested in an ESA project, to check if your state…

PhD Defence

It is well known that photography means writing with light. However, the meaning of “with” can be ambiguous. Film can be exposed outside of the camera. Historically, people have done so to render visible other forms of radiation than what we call light. In mid-2013, Andrew Littlejohn took several rolls…

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

Astronomers from, among others, SRON and Leiden Observatory have discovered long-sought intergalactic gas with ESA’s space telescope XMM-Newton. This gas is one of the pieces of the puzzle to map the total amount of ‘normal’ matter in the universe. The research will be published in Nature on 21 June…

We investigate how radiation pressure can be used to influence the mechanical motion of a micro-mirror suspended from springs.

The formation and evolution of galaxies is fundamentally driven by the formation of new stars out of cold gas.

The distinguished academic journal Science published an article about an important and extensive series of measurements made by the Centre for Isotope Research (CIO) of the University of Groningen. The measurements concern the dating of a lake bed sediment in the Suigetsu Lake in Japan.

At Leiden Observatory, researchers investigate the origin of stars and their planetary systems. They detect and characterize planets around other stars (exoplanets). They study how stars and planets form. And they follow molecules from interstellar clouds to nascent planet systems. This way they address…

PhD Defence

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.

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.

Promotor: Prof.dr. K.J. Batenburg

Promotor: J. Schaye

Promotores: Prof.dr. J. Aarts, Prof.dr. J.M. van Ruitenbeek