Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


A Cosmic Crash of Unexpected Proportions

An international research team investigates the distant galaxy cluster Abell 2744

The biggest known cosmic collision in the Universe took place in a distant galaxy cluster called Abell 2744. That is the conclusion of an international team of scientists investigating the debris of this massive crash with novel research methods that were developed at Heidelberg University’s Institute of Theoretical Astrophysics.

The image shows the galaxy cluster Abell 2744. It combines observations in the visible light spectrum with X-ray images of satellite Chandra (red) and clouds of dark matter (blue). The particularities of the system are clearly visible, for example a clump of dark matter with no stars or gas (northwest sector) and a clump of galaxies and dark matter without gas (western sector). The scale indicates a distance of 250,000 parsecs, approximately nine times the diameter of the visible part of our own galaxy, the Milky Way. In astronomy, the compass points East and West are switched, as shown at the bottom right corner of the image.
Image source: NASA, ESA, ESO, CXC, J. Merten (Heidelberg/Bologna) & D. Coe (STScl)

These methods enabled the scientists to reconstruct the course of events over a period of several hundreds of millions of years and thus to understand how large-scale structures develop in the Universe based on the interaction of different kinds of matter. Researchers from Brazil, Canada, Germany, Israel, Italy, Scotland, Spain, Taiwan and the United States of America collaborated on the investigation.

The astrophysicists observed the galaxy cluster Abell 2744 from an unprecedented number of angles with high-performance telescopes, among them the Very Large Telescope of the European Southern Observatory (ESO) in Chile, the Japanese Subaru Telescope in Hawaii and the Hubble and Chandra space telescopes. With the data gleaned from these observations, the research team headed by astrophysicist Dr. Julian Merten of the Heidelberg Institute of Theoretical Astrophysics was able to investigate the three essential components of galaxy clusters: galaxies and their stars, intergalactic gas and dark matter.

Each of the approx. 1,000 galaxies of Abell 2744 contains many billions of stars. However, this “visible” matter only makes up about five percent of the entire mass of the galaxy cluster. The galaxies “float” in the diffuse gas that is distributed between them, Dr. Merten explains. This “intergalactic gas” comprises 20 percent of the overall mass and was heated up so intensely by the effects of gravitational forces in the galaxy cluster that it emits radiation mostly in the X-ray wavelength band. The remaining 75 percent of the galaxy cluster consist of the mysterious “dark matter”.

To understand the processes going on in Abell 2744, the scientists aimed to determine the distribution of these three components as precisely as possible. This is easily accomplished for galaxies and intergalactic gas, but dark matter is much harder to pin down. It neither emits nor absorbs light and can only be detected through its gravitational attraction. However, during his time as PhD student at the Heidelberg Graduate School of Fundamental Physics, Julian Merten devised special methods for measuring the distribution of dark matter with the aid of an effect known as gravitational lensing.

When light rays emitted by galaxies far beyond Abell 2744 cut through the massive galaxy cluster, the gravitational attraction of the unevenly distributed dark matter changes the trajectory of the light travelling through the cluster. “The rays of light are ‘bent’ more or less strongly so that the images of the background galaxies appear distorted in a characteristic way,” says Dr. Merten. “By analysing this distortion for a large number of background galaxies we are able to chart out a map showing the distribution of dark matter.”

The surprising outcome of the analysis of Abell 2744 is that this system consists of at least four different galaxy clusters that must have collided over a period of about 350 million years. “The collision obviously separated the hot gas from the dark matter and led to an unusual and fascinating distribution of the three kinds of matter,” adds Dr. Merten. In the northwest sector, the scientists found an area where dark matter was separated from the other components in an unusual way. The hot gas leads the dark matter by a large distance and the galaxies do not appear to match the position of the dark matter, either. In the western sector, the researchers came across an area that contains both dark matter and galaxies, but no hot gas. “It looks as if this gas was stripped away completely in the central region of the cluster during the collision, and was left behind,” says Dr. Merten. Because of the large number of unusual and often mysterious phenomena, the researchers have dubbed Abell 2744 “Pandora’s cluster”.

A publication on these research findings entitled “Creation of Cosmic Structure in the Complex Galaxy Cluster Merger Abell 2744” will be appearing in ”Monthly Notices of the Royal Astronomical Society”. Preprint:

The Institute of Theoretical Astrophysics is part of Heidelberg University's Centre for Astronomy (ZAH).

Dr. Julian Merten
Zentrum für Astronomie der Universität Heidelberg (ZAH)
Institute of Theoretical Astrophysics
phone: +49 6221 54 8987
Communications and Marketing
Press Office, phone +49 6221 54 2311

Marietta Fuhrmann-Koch | idw
Further information:

More articles from Physics and Astronomy:

nachricht Sharpening the X-ray view of the nanocosm
23.03.2018 | Changchun Institute of Optics, Fine Mechanics and Physics

nachricht Drug or duplicate?
23.03.2018 | Fraunhofer-Institut für Angewandte Festkörperphysik IAF

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>