Are you good with statistics and interested in cosmology? Well, astronomers have issued a challenge to aid in the understanding of dark matter and dark energy — the mysterious stuff that makes up roughly 95 percent of our universe. Thirty-eight astronomers from 19 international institutions are issuing this challenge, called the GRavitational lEnsing Accuracy Testing 2008 (GREAT08).
Neither dark matter nor dark energy is directly visible — both seem to interact via gravity only. So, astronomers need to use detection methods that do not require directly observing. One of the most promising ways to detect, and analyze, dark matter and dark energy is with gravitational lensing. In this technique, astronomers study minute perturbations in the shapes of distant galaxies to map the universe's dark matter. Sarah Bridle of the University College London explains, “Streetlamps appear distorted by the glass in your bathroom window and you could use the distortions to learn about the varying thickness of the glass. In the same way, we can learn about the distribution of the dark matter by looking at the shapes of distant galaxies.” This dark matter distribution will in turn show the effect of dark energy on the universe’s growth structure.
Scientists must use precise image analysis to measure the perturbations in galaxy shapes through blurring, pixilation, noise and also theoretical uncertainty about the undistorted shapes of galaxies. Statistical tools needed to analyze the gravitational lensing images are not only related to astronomy, which is why the GREAT08 astronomers have issued the challenge.
Yes, astronomers have ways to analyze this type of data — these tools are adequate for current data. However, future dark energy surveys will require analysis techniques that are about 10 times more precise. Cosmologists will use methods developed for the GREAT08 challenge to analyze future dark energy survey data.
This challenge will take time. Those participants who are serious about the challenge are asked to work through 27 million galaxy images (in sets of 10,000) from 170 gigabytes of data. Including supplementary data, GREAT08 contains 200 gigabytes of simulated images with 30 million galaxy images.
If this is a challenge you think you’d be interested in, check out the GREAT08 handbook (PDF file). The competition deadline is April 30, 2009, and the results will be announced June 2009 at the latest. The GREAT08 challenge will award two winners, where the prize is a trip to the final workshop, to be held around June 2009.