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…

Two black holes, in close orbit around each other. Have they slowly drifted together, or did they emerge from two orbiting stars? Together with to colleagues form Amsterdam, Leiden astronomer Simon Portegies Zwart calculated that the second scenario is rather likely.

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

They are often referred to as ‘The Oscars of the Natural Sciences’: the Breakthrough Prizes in Life Sciences, Fundamental Physics and Mathematics. This year, the prize for physics went to the Event Horizon Telescope team, which took the first-ever picture of a black hole. Four Leiden astronomers were…

‘Space Antenna LISA will open an unprecedented window on the Universe,’ says astronomer Elena Maria Rossi. The mission will be the first one to detect Gravitational Waves from space. These can tell us more about the beginning of our Universe and the formation of black holes. With an NWO grant of twelve…

An international team of astronomers led by Violeta Gámez Rosas (Leiden University) has observed a supermassive black hole hidden in a ring of dust. This discovery fits the idea that the so-called active centers of galaxies are much more similar than observations show, because the viewing angle from…

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.

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

For the first time, astronomers have managed to take a photo of a supermassive black hole and its shadow. They used the Event Horizon Telescope (EHT), a worldwide network of eight radio telescopes that together form a virtual telescope the size of the earth. The news was presented in six press conferences…

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.

The brightness peak of the ring around M87's supermassive black hole has shifted 30 degrees counterclockwise in a year. This is shown by new images released by the Event Horizon Telescope consortium.

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…

Scientists are asking your help to find the origin of hundreds of thousands of galaxies that have been discovered by the largest radio telescope ever built: LOFAR. Where do these mysterious objects, which extend for thousands of light-years, come from? A new citizen science project called LOFAR Radio…

We don’t understand how some materials become superconducting at relatively high temperatures. Leiden physicists have now found a surprising connection with auxiliary black holes. It enables us to use our knowledge of black holes on the mystery of high-temperature superconductivity. Publication in Nature…

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…

Elena Maria Rossi is fascinated by black holes. Her appointment as a professor was a long-held wish, partly because there are so few female professors in her field. ‘My appointment is also a milestone for the Leiden Observatory.’

A European team of astronomers has discovered the largest stellar black hole in the Milky Way. It is more than thirty times as massive as our sun and is located in the constellation of Aquila, about two thousand light-years from Earth. The astronomers stumbled upon the black hole by chance while preparing…

Leiden astronomy Master's student Arend Moerman has received an A+ for his thesis research on the simulation of chaotic interactions of three black holes. The simulations, which he carried out together with his Leiden and Oxford colleagues, show that lighter black holes tend to slingshot each other…

Delve into the depths of black hole imaging as anthropologist Rodrigo Ochigame unveils the human decisions shaping its portrayal. Explore four alternative color choices at the 'Towards the Black Hole' exhibit, now showing at Rijksmuseum Boerhaave, Leiden.

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…

Not everything that comes close to a black hole is swallowed by it. Black holes can also hurl material away, and that chance turns out to be considerably bigger than previously thought. Martijn Oei's accidental discovery and his subsequent research on it earned him a cum laude promotion on 12 Decemb…

The orbits of 27 stars orbiting closely around the black hole at the center of our Milky Way are very chaotic. As a result, researchers cannot predict with confidence where they will be in about 462 years. ‘That is astonishingly short,’ says astronomer Simon Portegies Zwart who collaborated on the r…

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…

Lecture, Oort lecture

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.

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.

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

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

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.

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

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.

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).

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