Ground-breaking simulation for researching the “dark” cosmos

For the first time, scientists have succeeded in carrying out a cosmological simulation with several trillion particles. The simulation on the CSCS supercomputer Piz Daint provides an important basis for researching the universe with the Euclid satellite, which will be launched into space in 2020.

Euclid Flagship
Image copyright J. Stadel 2017

>> View the 2540px image

A small piece of the Simulation showing the complex formed by the dark matter through the action of gravity and the expansion of the Universe. White regions are the voids and the golden concentrations are the halos, where the density of dark matter is the lowest and highest respectively. These two extremes are delineated and connected by the filaments which are shown here in black. The golden colored dark matter halos host the galaxies in our Universe. The image measures 2.5 billion light years across and our entire Milky Way Galaxy would fit inside of a single golden colored pixel.

Image copyright J. Stadel 2017

>> View the full 5000px image

A slice through the invisible universe of dark matter is shown here extending from the present, located at the centre, to the most distant regions observable by the Euclid satellite, 10 billion light years to the left and right. The mission of Euclid will be to indirectly measure this network-like structure through the effect of gravitational lensing. Since light will have taken 10 billion years to travel from the left and right sides of the image to "us" in the center, we see that the Universe in the past looked considerably smoother, and that the large empty regions, known as voids, are much more prominent at the present.

>> Read the full article in English
>> Read the full article in German

>> Swiss National Supercomputing Centre (CSCS) article
>> Euclid Consortium press release
>> UZH Press Release

October 2016

Wie Riesenplaneten entstehen

Junge Planeten werden aus Gas und Staub gebildet. Um herauszufinden, was bei ihrer Geburt genau passiert, simulierten die Astrophysikerin Judit Szulágyi von der ETH Zürich und der UZH-Astrophysiker Lucio Mayer unterschiedliche Szenarien am Schweizer Supercomputerzentrum (CSCS).

Die Simulation zeigt die Entstehung eines jungen Planeten. (Bild: Frederic Masset, ETH Zürich / CSCS).

>>Read more

August 2016

Erste Gravitationswellen bilden sich nach 10 Millionen Jahren

Kollidieren zwei Galaxien, löst die Verschmelzung der zentralen schwarzen Löcher Gravitationswellen aus, die sich wellenartig über das ganze Weltall verbreiten. Ein internationales Forschungsteam mit Beteiligung der Universität Zürich hat errechnet, dass dies etwa 10 Millionen Jahre nach der Verschmelzung der Galaxien passiert – viel schneller als bisher angenommen.

>>Read more

Mar 2016

Illuminating the Universe’s Ignition

Shapiro team reionization simulation from OLCF on Vimeo.

This video shows a snapshot of how hot, ionized gas (bright patches) created by millions of galaxies that clustered in space along the threads of a cosmic web, might have been distributed within a piece of the expanding universe 300 million light-years across today, centered on our Milky Way galaxy, when half the volume was still occupied by cold and neutral gas (dark regions).

Read more »

Dec 2016

Billiards and planet formation
Volker Hoffmann, Simon Grimm, Ben Moore & Joachim Stadel
Institute for Computational Science, University of Zurich.


Rocky Earth-like planets are thought to be the end result of a vast number of gravitational interactions and collisions between smaller bodies.
>>> Read full press release
Dec 2014

The History of the Universe in 24 hours with Ben Moore

Nov 2014


Academia Industry Modeling Week: Programmierter Erfolg
In der Academia Industry Modeling Week haben Doktorierende Lösungen für aktuelle und konkrete Forschungsfragen industrieller Unternehmen gesucht. Die Veranstaltung bot Gelegenheit, untereinander und mit der Industrie Kontakte zu knüpfen. 

Oct 2014

«Aliens sehen ganz anders aus»

Der Astrophysiker Ben Moore veröffentlicht sein zweites populäres Buch. In «Da draussen. Leben auf unserem Planeten und anderswo», erklärt er, wie das Leben auf der Erde entstanden ist, wo es im Universum (intelligentes) Leben geben und wie dieses aussehen könnte. UZH News sprach mit Ben Moore über intelligente Aliens, Delfine und Science-Fiction-Romane. 


Apr 2014
This artist's illustration shows the hypervelocity star cluster HVGC-1 escaping from the supergiant elliptical galaxy M87. HVGC-1 is the first runaway star cluster discovered by astronomers. It is fated to drift through intergalactic space. Credit: David A. Aguilar (CfA)

Entire star cluster thrown out of its galaxy

( —The galaxy known as M87 has a fastball that would be the envy of any baseball pitcher. It has thrown an entire star cluster toward us at more than two million miles per hour. The newly discovered cluster, which astronomers named HVGC-1, is now on a fast journey to nowhere. Its fate: to drift through the void between the galaxies for all time.
"Astronomers have found runaway stars before, but this is the first time we've found a runaway ," says Nelson Caldwell of the Harvard-Smithsonian Center for Astrophysics. Caldwell is lead author on the study, which will be published in The Astrophysical Journal Letters and is available online.

Nov 2011

Asteroid in Sicht

In der Nacht von Dienstag auf Mittwoch wird Asteroid «2005 YU55» an der Erde in einem Abstand von 325'000 Kilometer vorbeisausen. Auswirkungen werden auf der Erde nicht zu spüren sein. Irgendwann in der Zukunft wird es für die Erde aber wieder gefährlich werden, erklärt Ben Moore, Professor für Astrophysik an der Universität Zürich. 

Read the full article on the University of Zurich website:

Sep 2011

Earth-Moon planetary systems: TV coverage

May 2011

How common are Earth-Moon planetary systems?


Our Moon formed via a giant impact between our young Earth and a Mars sized proto-planet over four billion years ago. The material torn from the Earth’s surface during the collision accumulated in orbit and formed our familiar satellite. After its formation the Moon was ten times closer to the Earth than it is today and it has drifted slowly away to its present position. Its early intense gravitationally attraction would have caused tidal waves to pass across the Earth’s surface several times per day which may have influenced the initial development of life. 

pdf Read More

pdf Read the article in The "SonntagsZeitung" 26.06.2011

The full article will be published in the journal Icarus and can be found here:

Sep 2011 UPDATE: TV coverage

August 2010

New model: supermassive black holes arrived early, find UniZH team in a paper on the 26 August issue of "Nature" 

Direct formation of supermassive black holes via multi-scale gas inflows in galaxy mergers

Density map of the gas in the nuclear disk at three different times (columns a b and c). Upper panels: large-scale structure of the disk. Lower panels: zoom-in on the collapsing central cloud.

Previously published models of supermassive black hole formation have struggled to explain the fact that  according to observations of distant quasars  supermassive black holes were already in place less than a billion years after the Big Bang. A new series of numerical simulations from a team led by Lucio Mayer at the University of Zurich with PhD student Simone Callegari also from UniZH,
finds that the conditions for direct collapse into a supermassive black hole can arise naturally on this time scale from mergers between massive protogalaxies.Multi-scale gas inflows give rise to an unstable, massive nuclear gas disk that expands to form a sub-parsec scale gas cloud in only 100,000 years. The cloud undergoes gravitational collapse, which leads to the formation of a massive black hole.

The paper:

UNIZH press release
USA TODAY,+Geography/Towns,+Cities,+Counties/Zurich

January 2010

Bulgeless galaxies with dark matter cores simulated

The picture shows the evolution of the assembly of the dwarf galaxy from high to low redshift.

Until now the origin of bulgeless galaxies and slowly rising rotation curves in low mass galaxies was a major puzzle of the cold dark matter model (CDM) for structure formation. Lucio Mayer and colleagues have performed the first supercomputer simulations that forms a bulgeless galaxy with a realistic rotation curve owing to unprecedented resolution.
The work is described on the journal Nature, issue of January 14, 2010.
"Bulgeless galaxies with dark matter cores simulated" Nature, 463, 203-206, 2010.

The simulation resolves the sites of star formation, giant molecular clouds, and shows that outflows generated by supernovae explosions prevent the formation of a bulge by removing baryonic mass from the center of the dwarf galaxy. Removal is fast enough to generate a rapid expansion of inner dark matter component. The final dark matter profile is thus shallower than that predicted by dark-matter only simulations.

Press release Uni Zurich:


June 2009

Baby Milky Way modeled

Researchers unveil state-of-the-art simulation of galaxy formation


Galaxy Formation in Progress from Science News on Vimeo.

This movie models how a galaxy acquires most of its gas — the raw material for making stars. Red is hot gas, blue shows the cold streams of gas that flow like a river toward the galaxy’s center, and green shows gas that has been stripped out of satellite galaxies and enriched in metal content by supernova explosions.

Found in "Baby Milky Way Modeled" online

Credit: B. Moore, Oscar Agertz and Romain Teyssier/University of Zurich