Feature - The dynamics of dark energy: ZEN probes the limits
The answers are out there somewhere, and researchers with the ZEN project are keen to find them.
ZEN-standing for Zoom sur l'Energie Noire or "zoom on dark energy"-is a computer model designed to enable new estimates about the nature of dark energy.
Mysterious, not dark
"Dark energy has a very surprising property: it acts like negative pressure," says ZEN project leader Andre Tilquin of the Marseilles Centre for Particle Physics in France. "This means the expansion of our universe is accelerating; before we thought the expansion of the universe was decelerating due to its own mass."
Tilquin's goal is to calculate the dynamics of this force with new accuracy, using ZEN.
The ZEN model combines observations from different experiments within a framework of interdependent cosmological and astrophysical parameters-new information about one force will affect what we know about all other forces. The tool allows researchers to analyze new data quickly and coherently.
"By combining information from many experiments we can accurately measure all the parameters that describe the universe," says Tilquin.
Part of EGEE's Earth Science Research virtual organization, using DataGrid, ZEN currently uses input from three astronomical experiments: Canada-France-Hawaii Telescope Legacy Supernova Survey, cosmological microwave background from NASA's Wilkinson Microwave Anisotropy Probe mission and baryonic acoustic oscillations from the Sloan Digital Sky Survey.
Answers that demand new answers
Tilquin and his colleagues are now focused on the dynamics of dark energy: Is its strength constant? Or does it evolve with time? If constant, we will have evidence for Einstein's proposed "cosmological constant."
And if not?
"If we discover that this parameter is not constant in time," says Tilquin, "then we have to think about a new particle, and researchers will then try to discover it with accelerators, such as the Tevatron or Large Hadron Collider."
It is possible that this new particle is the Higgs boson, an as-yet-unobserved particle predicted to impart mass to particles through a mechanism that leaves remaining energy in a vacuum. This remaining energy may be responsible for the cosmological constant.
- Danielle Venton, EGEE
On 7 March 2008, NASA's Wilkinson Microwave Anisotropy Probe mission published results suggesting that the cosmological constant is still the best explanation of dark energy.