Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When galaxies collide: Supercomputers reproduce fluid motions of cosmic duet

02.06.2006


Simulations forecast favorable conditions for verifying Einstein predictions


The gaseous disks of two galaxies collide in this series of images produced in a supercomputer simulation. Approximately three billion years after the collision begins, the two supermassive black holes at the center of the galaxies merge. Such mergers produce strong gravitational waves, which scientists hope to detect with the proposed Laser Interferometer Space Antenna. An international team of scientists led by Stelios Kazantzidis of the Kavli Institute for Cosmological Physics performed the simulations to elucidate the processes that lead to the merger of supermassive black holes and the production of gravitational waves. Credit: Image courtesy of Stelios Kazantzidis


In this image from a supercomputer simulation, gravitational interaction between colliding galaxies generates spectacular tidal tails, plumes and prominent bridges of material connecting the two galaxies. Credit: Image courtesy of Stelios Kazantzidis



A wispy collection of atoms and molecules fuels the vast cosmic maelstroms produced by colliding galaxies and merging supermassive black holes, according to some of the most advanced supercomputer simulations ever conducted on this topic.

"We found that gas is essential in driving the co-evolution of galaxies and supermassive black holes," said Stelios Kazantzidis, a Fellow in the University of Chicago’s Kavli Institute for Cosmological Physics. He and his collaborators published their in February on astro-ph, an online repository of astronomical research papers. They also are preparing another study.


The collaboration includes Lucio Mayer from the Swiss Federal Institute of Technology, Zurich, Zwitzerland; Monica Colpi, University Milano-Bicocca, Italy; Piero Madau, University of California, Santa Cruz; Thomas Quinn, University of Washington; and James Wadsley, McMaster University, Canada. "This type of work became possible only recently thanks to the increased power of supercomputers," Mayer said. Improvements in the development of computer code that describes the relevant physics also helped, he said.

"The combination of both code and hardware improvement makes it possible to simulate in a few months time what had required several years of computation time only four to five years ago."

The findings are good news for NASA’s proposed LISA (Laser Interferometer Space Antenna) mission. Scheduled for launch in 2015, LISA’s primary objective is to search the early universe for gravitational waves. These waves, never directly detected, are predicted in Einstein’s theory of general relativity.

"At very early times in the universe there was a lot of gas in the galaxies, and as the Universe evolved the gas was converted into stars," Kazantzidis said. And large amounts of gas mean more colliding galaxies and merging supermassive black holes. "This is important because LISA is detecting gravitational waves. And the strongest source of gravitational waves in the universe will be from colliding supermassive black holes," he said.

Many galaxies, including the Milky Way galaxy that contains the sun, harbor supermassive black holes at their center. These black holes are so gravitationally powerful that nothing, including light, can escape their grasp.

Today the Milky Way moves quietly through space by itself, but one day it will collide with its nearest neighbor, the Andromeda galaxy. Nevertheless, the Milky Way served as a handy model for the galaxies in the merging supermassive black hole simulations. Kazantzidis’s team simulated the collisions of 25 galaxy pairs to identify the key factors leading to supermassive black hole mergers.

For these mergers to occur, the host galaxies must merge first. Two gas-poor galaxies may or may not merge, depending on the structure of the galaxies. But whenever gas-rich galaxies collide in the simulations, supermassive black-hole mergers typically followed.

"The more supermassive black holes that you predict will merge, the larger the number of sources that LISA will be able to detect," Kazantzidis said. As two galaxies begin to collide, the gas they contain loses energy and funnels into their respective cores. This process increases the density and stability of the galactic cores. When these cores merge, the supermassive black holes they host also merge. When these cores become disrupted, their supermassive black holes fail to merge.

Each simulation conducted by Kazantzidis consumed approximately a month of supercomputing time at the University of Zurich, the Canadian Institute for Theoretical Astrophysics, or the Pittsburgh Supercomputing Center.

The simulations are the first to simultaneously track physical phenomena over vastly differing scales of time and space. "The computer can focus most of its power in the region of the system when many things are happening and are happening at a faster pace than somewhere else," Mayer said.

When galaxies collide, the billions of stars contained in them fly past one another at great distances. But their surrounding gravity fields do interact, applying the cosmic brakes to the two galaxies’ respective journeys. The galaxies separate, but they come back together, again and again for a billion years. At each step in the process, the galaxies lose speed and energy.

"They come closer and closer and closer until the end, when they merge," Kazantzidis said. The simulations have produced effects that astronomers have observed in telescopic observations of colliding galaxies. Most notable among these is the formation of tidal tails, a stream of stars and gas that is ejected during the collision by the strong tidal forces.

On a smaller scale, astronomers also observe that colliding galaxies display increased nuclear activity as indicated by brighter cores and increased star formation.

Despite the success of the simulations, Kazantzidis and his team still work to improve their results. "It’s a struggle every day to increase the accuracy of the computation," he said.

Steve Koppes | EurekAlert!
Further information:
http://www.uchicago.edu

More articles from Physics and Astronomy:

nachricht Structured light and nanomaterials open new ways to tailor light at the nanoscale
23.04.2018 | Academy of Finland

nachricht On the shape of the 'petal' for the dissipation curve
23.04.2018 | Lobachevsky University

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: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Quantum Technology for Advanced Imaging – QUILT

24.04.2018 | Information Technology

AWI researchers measure a record concentration of microplastic in arctic sea ice

24.04.2018 | Earth Sciences

Complete skin regeneration system of fish unraveled

24.04.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>