Solving the Galactic 'Axis of Evil' Problem

One of the most enduring and difficult mysteries in astronomy today is a conundrum called the “Axis of Evil.” Recently, experts gathered in the United Kingdom to discuss it, as well as the latest measurements conducted on galaxy clusters.

What this contradiction refers to is how to measure the weight of the Universe, and which method to trust for accuracy. Any two methods used to weigh a distant galactic cluster, for example, can easily be made to show similar results, but applying a third always produces incompatible results.

In other words, it looks like the mass of these massive structures – the largest forms of organized matter in the Cosmos – depends entirely on what method we use to look for them. This issue was the main topic at the newest conference, which reunited 40+ experts in cluster astronomy.

The conference – organized by the Astrophysics Research Institute (ARI) – was entitled “Scaling Relations of Galaxy Clusters.” It was hosted by the Liverpool John Moores University, and made possible by funds provided by the Royal Astronomical Society (RAS).

Astronomers who gathered at the talks are experts in cluster astronomy, which is the science of studying the most massive, gravitationally-bound objects in the entire Universe. Through their careers, these scientists observed a certain incongruence in their measurements.

After double-checking their results, they established that this was not a statistical fluke or a calculation error. Rather, the difference was found to stem form the method each of their teams used to measure the mass of galaxy clusters.

The three main methods involve using either X-ray, optical and millimeter wavelengths. The results these studies obtain are considerably different, SpaceRef reports. Scientists are now waiting for detailed results from missions such as the European Space Agency's (ESA) Planck telescope.

This instrument scans the cosmic microwave background (CMB), with the express purpose of finding signs of cluster and superclusters. The data is then compared to information collected by the Sloan Digitized Sky Survey and new X-ray observations made with the ESA XMM-Newton telescope.

“I saw this meeting as an opportunity to bring together experts who study clusters at only one wavelength and don't always talk to their colleagues working at other wavelengths,” says Chris Collins.

“The results presented are unexpected and all three communities (optical, X-ray and millimeter) will need to work together in the future to figure out what is going on,” adds the expert, who organized the meeting. He holds an appointment as a professor at the Liverpool John Moores University.