FAIRFAX, Va.—A new web site developed by researchers at George Mason University and Oxford University will give everyone the chance to contribute to science by playing a 'cosmic slot machine' and comparing images of colliding galaxies with millions of simulated images of galactic pile-ups.
These collisions, which astronomers call 'galactic mergers', could be the key to finding out why the universe contains the mix of galaxies it does – some with trailing spiral arms, others more like compact 'balls' of stars.
Galaxy Zoo Mergers (http://mergers.galaxyzoo.org ), which goes live today, is an international project led by scientists from Oxford University in the UK and George Mason University in the US. The Mergers web site is a shoot-off of an earlier project from Oxford called Galaxy Zoo, which is a web site that allows anyone—scientist or not—to log in and help categorize the more than million galaxies of our universe into different classifications with a few clicks of the keyboard.
Now Mergers is going even further by allowing these citizen scientists to do computer modeling of galaxies to determine how a collision happened.
Surprisingly, humans are much better than computers at spotting the best match between a real galactic merger image and a random selection of simulated merger images. Because the simulated images reflect the different variables involved in galaxy formation, the information from people using the site will revolutionize scientists' understanding of these collisions.
"Visitors to the Galaxy Zoo Mergers site use what's rather like a giant slot machine, with a real image of a galactic merger in the center and eight randomly selected simulated merger images filling the other eight 'slots' around it," says John Wallin, associate professor of computational and data sciences at George Mason University. "By randomly cycling through the millions of simulated possibilities and selecting only the very best matches, our visitors are helping to build up a profile of what kind of factors are necessary to create the galaxies we see in the universe around us. And, hopefully, they are having fun, too!"
Users do more than simply select images. They can also take direct control of the simulations – choosing more or fewer stars or "flipping" galaxies – in order to provide an exact match to what we see in the universe.
"These volunteers that participate are not just users," says Dr. Chris Lintott of Oxford University, the project lead for the Galaxy Zoo project. "They're doing science. They're doing the analysis we don't have time for, because there could never be enough professional astronomers to do the job properly."
The project will focus on around 3,000 images of real galactic mergers identified through the Galaxy Zoo project – it also features some new images of these mergers taken by the Hubble Space Telescope. The next stage will be to investigate the before and after of these colliding galaxies to discover what caused them and what will happen next – rather like trying to capture the slow motion detail of the moments before a car crash and predict the aftermath.
"These collisions take millions of years to unfold, and so all we get from the universe is a single snapshot of each one. By producing simulations, we will be able to watch each cosmic car crash unfold in the computer," says Wallin. "By reconstruct these collisions, our users will help us understand how galaxies have changed over the history of the universe."