Schalm

Why do black holes emit thermal radiation? And how does a closed quantum system thermalize?

What is dark matter? How do supermassive black holes form? ‘Primordial’ black holes might hold the answer to these long-standing questions. Leiden and Chinese cosmologists have identified a new way in which these hypothetical objects could be produced just after the Big Bang. Publication in Physical…

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

An international team of astronomers has witnessed a cosmic weather event that has never been seen before.

Physicists understand little about quantum matter, which is a building block of future quantum computers. Theorists have now discovered that black holes with ‘dreadlocks’ harbor a similarly exotic order pattern, which makes calculations on quantum matter easier. Publication in Physical Review Letter…

An international team of astronomers has published a map of the sky showing over 25,000 supermassive black holes. The map, to be published in the journal Astronomy & Astrophysics, is the most detailed celestial map in the field of so-called low radio frequencies. The astronomers, including Leiden astronomers,…

Meet the newest Full Professor at the Leiden Observatory: Joe Hennawi. All the way from Santa Barbara, California, Hennawi will strengthen the astronomy institute. In Leiden, he will use his recent ERC Advanced Grant to study how supermassive black holes come into existence.

Stars orbit black holes while jumping up and down. This is the prediction of a theoretical model developed by Leiden physicist Satish Kumar Saravanan, based on Einstein’s theory of relativity. He defends his PhD thesis on July 7th.

For only the second time ever, astronomers have linked a neutrino to an object outside our Milky Way. These observations were made using telescopes both on Earth and in space. The researchers, including Leiden astronomer Sjoert van Velzen, were able to trace the neutrino to a black hole that is devouring…

The Event Horizon Telescope (EHT) collaboration receives the 2021 Royal Astronomical Society Group Achievement Award. In April 2019, the EHT team presented the first-ever photograph of the shadow of a black hole. Leiden professor Huib-Jan van de Langevelde has been director of EHT since last year. Three…

Finally we know for sure that there is a black hole at the centre of our own galaxy. Today, astronomers unveiled the first ever photo of Sagittarius A*, a super-massive object at the centre of the Milky Way. This picture could only be taken thanks to the cooperation of telescopes worldwide.

The Dutch Black Holes Consortium receives 4.9 million euros from NWO for unravelling the mysteries of black holes and other mysteries of the universe. The Astronomy and Society group at Leiden Observatory is affiliated to use the leading research to introduce people of all ages and background, and children…

One unravels the origin of the largest black holes in the universe, the other investigates the influence of stellar wind on the atmosphere of exoplanets. Both Elena Maria Rossi and Aline Vidotto receive a Vici grant for their research into the mysteries of the universe. ‘I have no idea yet how we can…

An international team of researchers observed the full extent of the evolution of hot gas produced by an active black hole for the first time. As it evolves, the hot gas encompasses a much larger area than previously thought and even impacts objects residing at great distances. Their study is published…

All supermassive black holes in the centres of galaxies appear to have periods when they swallow matter from their close surroundings. But that is about as far as the similarities go. That's the conclusion reached by British and Dutch astronomers from their research with ultra-sensitive radio telescopes…

Promotores: S.F. Portegies Zwart, E. M. Rossi

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…

An Active Galactic Nucleus (AGN) is a highly luminous region at the center of a galaxy, powered by the accretion into a supermassive black hole and emitting energy from radio waves to gamma rays, often outshining the host galaxy.

The Sun and all the stars in the night sky reside in the Milky Way galaxy. In the at-rest reference frame of the Galaxy, typical stars travel with velocities of about 100-200 kilometres per second.

The thesis deals with the study of giant radio galaxies (GRGs), which are radio galaxies of megaparsec sizes.

In this dissertation, matching, entropy, holes and expansions come together. The first chapter is an introduction to ergodic theory and dynamical systems.

Promotor: Prof.dr. S.F. Portegies Zwart

In this thesis, we use low-frequency and high-frequency radio observations to address the following questions regarding quasars: is the radio loud/quiet quasar dichotomy real?

The first photo of a black hole and measuring anxiety in the brain... From 13 until 22 May we're serving a free slice of science with your pizza.

Anthropologist Rodrigo Ochigame studies how AI is changing the practice of scientific research. From astrophysics to mathematics to climate science, they find that the adoption of new AI models is raising questions about what counts as reliable scientific evidence.

Truth is stranger than fiction. In 1997 Juan Maldaceña discovered a remarkable dictionary that translates equation for equation the physics of black holes in string theory into the more conventional physics of quantum mechanics of interacting particles. The remarkable possibility exists that…

Through the clever use of two types of telescopes, a team of researchers has produced stunning images of clusters of galaxies. This not only produces beautiful images, but also provides more information about the enormous amounts of energy released around supermassive black holes in clusters. The astronomers,…

Since the Middle Passage is in the North Atlantic, and the North Atlantic has a relationship with the arctic, what relationship does the Arctic have with the Middle Passage? How can this relationship be used to provide a space of healing by uncovering Afro/diasporic counter narratives?

Rossi

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).

This thesis explores the theoretical and observational properties of distant massive galaxies that harbour active black holes in their centres and shine brightly at radio wavelengths.

The origin and evolution of galaxies are closely linked to many different physical phenomena.

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.

Smart algorithms and powerful processors are just as essential for astronomy as big telescopes. Astronomers at Leiden University therefore constantly operate at the interface between astronomy and data science.

This thesis presents pioneering work on the panchromatic emission of some of the most luminous galaxies in the early Universe: star forming galaxies and active galactic nuclei.

Our research primarily focuses on the early universe and its origins in theories that go beyond the Standard Model of particle physics.

In this thesis new methodologies are developed for the detection and systematic study of radio sources in the early universe. This allows us to gain a deeper understanding of the formation and evolution of galaxies, the activity of supermassive black holes, and the final phase transition of our universe:…

Outflows are crucially important for the gas budget and evolution of luminous star-forming galaxies and AGNs, with observed mass outflow rates of the same order as the star formation rate. Greater star formation and black hole growth lead to more intense feedback and outflows, resulting in self-regulated…

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…

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,…

The Leiden astronomer Huib van Langevelde) has been selected as the new director of the Event Horizon Telescope (EHT). The EHT is a collaboration involving about 350 scientists from 18 countries. It combines the ALMA array in Chile with sub-millimeter telescopes around the world and published the first…

The physics of black holes appears to be as far removed from the physics of electrons in metals as it can be.

In this thesis, we have used numerical approaches to study the effects of translational symmetry breaking on strange metallic systems as realised by the holographic duality⁠.

Continuous optimization is never easy: the exact solution is always a luxury demand and the theory of it is not always analytical and elegant.