Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Galaxy evolution in cyber universe matches astronomical observations in fine detail

07.06.2006


Scientists at the University of Chicago have bolstered the case for a popular scenario of the big bang theory that neatly explains the arrangement of galaxies throughout the universe. Their supercomputer simulation shows how dark matter, an invisible material of unknown composition, herded luminous matter in the universe from its initial smooth state into the cosmic web of galaxies and galaxy clusters that populate the universe.


This image from a supercomputer simulation of the evolution of the universe shows a cubic volume of outer space measuring approximately 280 million light years across. At this stage, the universe is 13.4 billion years old (the present). The bright dots correspond with high concentrations of dark matter, which are associated with sites of galaxy formation. The simulation shows how dark matter, an invisible material of unknown composition, herded luminous matter in the universe from its initial smooth state into the cosmic web of galaxies and galaxy clusters that populate the universe. The University of Chicago’s Andrey Kravtsov, Charlie Conroy and Risa Weschlser will describe these findings in a paper published in the June 20 issue of the Astrophysical Journal. Credit: Image courtesy of Andrey Kravtsov


This image from a supercomputer simulation of the evolution of the universe shows a cubic volume of outer space measuring approximately 280 million light years across. At this stage, the universe was 470 million years old. The bright dots correspond with high concentrations of dark matter, which are associated with sites of galaxy formation. The simulation shows how dark matter, an invisible material of unknown composition, herded luminous matter in the universe from its initial smooth state into the cosmic web of galaxies and galaxy clusters that populate the universe. The University of Chicago’s Andrey Kravtsov, Charlie Conroy and Risa Weschlser will describe these findings in a paper published in the June 20 issue of the Astrophysical Journal. Credit: Image courtesy of Andrey Kravtsov



Previous studies by other researchers had already verified the main features of this scenario, called the cold dark matter model. The Chicago team further extended this work by comparing the results of their supercomputer simulations to the newest, most detailed astronomical observations available today. They found an excellent fit, and they did so without basing their simulations on a lot of complex assumptions.

"The model we use is really, really simple," said Andrey Kravtsov, Associate Professor in Astronomy & Astrophysics. "We want to see how well this framework can do with a minimum number of assumptions."


A paper co-authored by Kravtsov, Charlie Conroy and Risa Wechsler describing these findings will be published in the June 20 issue of the Astrophysical Journal. The research was funded by a grant from the National Science Foundation, with additional support from the National Aeronautics and Space Administration.

Simulations that Kravtsov’s team conducted two years ago had predicted that galaxies of different luminosity or brightness would cluster differently when the universe was young than they do today. The team’s Astrophysical Journal paper verifies that prediction and shows that similar differences appear in the recent data.

"In the early stages of evolution of the universe, each galaxy has a high probability of having a close neighbor of similar luminosity," Kravtsov said, much more so than galaxies today. "That was what was predicted and that’s what the observations now seem to show us."

The data that Kravtsov’s team compared to its simulations came from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) survey, and from the Sloan Digital Sky Survey.

Using the Keck 10-meter telescopes in Hawaii, DEEP2 took detailed observations of how galaxies were clustered seven billion years ago, when the universe was approximately half its current age. The Sloan Survey, meanwhile, provided additional data regarding galaxy clustering from more recent epochs in the history of the universe.

"We essentially have data on the distribution of galaxies over most of the evolution of the universe, and the data are accurate," Kravtsov said. "Although the measurements at earlier epochs have larger errors, due to smaller data sets, their accuracy and power to constrain theoretical models is quite remarkable."

The Chicago scientists based their supercomputer simulations on the assumption that galaxies form in the center of dark-matter halos.

According to this scheme, gravity causes the dark matter in these regions to collapse into halos. These halos provide a central location where normal matter consisting of hydrogen, helium and a small amount of heavier elements would collect in gaseous form. Once this gas had cooled and condensed, it achieved sufficient density for star formation to begin on a galactic scale.

When the Chicago team compared the distribution of galaxies in its cyber universe to the real one, "that scheme turned out to work extremely well," Kravtsov said. "It wasn’t guaranteed that it would actually work so well in reproducing the data."

Some fields of astrophysics are less fortunate: they have a large body of data but no way to explain it. "The data just kind of hang there. Nobody quite understands what it’s telling us or how to interpret it."

But the Chicago simulations further support the idea that the universe behaves the way the cold dark matter scenario tells them it should, that galaxies tend to form in high-density regions of dark matter.

"We understand the distribution of these dark-matter halos, and the implication of this analysis is that we also understand how the properties of these halos are related to galaxy luminosity, how bright the galaxy is," Kravtsov said.

Brighter galaxies also are found in more pronounced large-scale structures. "If you look at fainter galaxies, their distribution becomes more diffuse. We can still see structure, but it’s not as pronounced."

Additional data continues to become available. For example, the Sloan Survey has gone beyond mapping the galaxies to include measurements of the dark matter that surrounds them. And other new, high-quality data regarding the distribution of galaxies from the very early stages in the evolution of the universe are becoming available. The first comparisons of the theory’s predictions with that data indicate good agreement over the span of about 12 billion years, Kravtsov said.

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

More articles from Physics and Astronomy:

nachricht Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

nachricht Seeing the quantum future... literally
16.01.2017 | University of Sydney

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: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>