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."
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!
Astronomers release most complete ultraviolet-light survey of nearby galaxies
18.05.2018 | NASA/Goddard Space Flight Center
A quantum entanglement between two physically separated ultra-cold atomic clouds
17.05.2018 | University of the Basque Country
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology