Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists model physics of a key dark-energy probe

13.07.2011
Simulations improve characterization of cosmology’s ‘standard ruler’

Ohio State University researchers are leveraging powerful supercomputers to investigate one of the key observational probes of "dark energy," the mysterious energy form that is causing the expansion of the universe to accelerate over time.


Produced by the Sloan Digital Sky Survey, this three-dimensional map of the distribution of galaxies shows Earth at the center, and represents each galaxy with a single point. Large astronomical surveys, such as SDSS, rely upon a model of Baryon Acoustic Oscillations to provide a cosmological "standard ruler" for determining length scale. Ohio State University's Chris Orban and David Weinberg, Ph.D., have employed Ohio Supercomputer Center resources to simplify and better characterize that BAO model. Credit: M. Blanton and SDSS

The OSU project, led by Chris Orban, a graduate research fellow in physics at Ohio State's Center for Cosmology and Astro-Particle Physics, focuses on simulations created on Ohio Supercomputer Center (OSC) systems to simplify and better characterize a subtle dark matter clustering feature. The new model allows cosmologists to gain a more accurate understanding of certain aspects of large-scale structure, such as the effect of the expansion of the universe on the growth of density fluctuations.

"Knowing how the dark matter 'reacts' to the expansion of the universe is crucial for learning the most about dark energy and dark matter from large astronomical surveys like the Sloan Digital Sky Survey, of which OSU is a collaborating member," said Orban. "In particular, there is a subtle clustering feature seen in this data set called 'Baryon Acoustic Oscillations' (BAO), which turns out to be very useful for constraining cosmological parameters like the equation of state of dark energy."

The oscillations come from fluctuations in the distribution of hot plasma in the early universe; researchers can identify this feature by measuring the cosmic microwave background.

"The BAO signature gets imprinted on the dark matter very early on, but the feature changes over cosmic time, potentially biasing its use as a cosmological tool," Orban explained. "It's a complicated non-linear problem, and physicists are very fond of simplifying complicated problems to gain a more in-depth understanding. This is exactly what we did for the first time, in our paper, using N-body simulations."

"For current state-of-the-art astronomical surveys, the main non-linear effects that we investigate in the paper are negligible compared to other sources of error, but next-generation surveys will need to be far more sophisticated in this regard," said Orban's academic advisor, David Weinberg, Ph.D., who is a professor of astronomy at OSU and the project scientist for the Sloan Survey. "This places the utmost importance on making reliable and precise predictions for these non-linear effects, a task which cosmological N-body simulations are in many ways well-suited to do."

Since early 2009, Orban and Weinberg have employed nearly 200,000 processor-hours of computational time on the OSC's flagship Glenn Cluster and eight terabytes of storage space on its Mass Storage Environment. The Glenn Cluster offers researchers more than 9,600 Opteron cores, 24 terabytes of memory and a peak computational capability of 75 teraflops – which translates to 75 trillion calculations per second.

For software, the researchers employed the state-of-the-art Gadget-2 N-body code to calculate the trajectories of more than a hundred million particles, and set the initial conditions using the 2LPT code developed by their collaborators at New York University.

"This research project represents a fantastic conjunction of people and disciplines," observed Ashok Krishnamurthy, co-executive director of OSC. "It brought together professionals in the fields of physics, astronomy and computational science to produce impressive results that might not otherwise have come together for many years. OSC is proud to have contributed to these achievements."

Orban and Weinberg authored a paper on this research, "Self-similar Bumps and Wiggles: Isolating the Evolution of the BAO Peak with Power-law Initial Conditions," which is slated for publication in the journal Physical Review D.

"We're both pretty proud of the final product, which we've been working on for about two and a half years," Orban said. "Our production runs represent by far the largest set of cosmological simulations ever performed at The Ohio State University."

Jamie Abel | EurekAlert!
Further information:
http://www.osc.edu

Further reports about: Cluster N-body OSU Ohio Orban dark energy dark matter expansion of the universe

More articles from Physics and Astronomy:

nachricht SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | 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

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>