RAS: Astronomers Reveal a Cosmic 'Axis of Evil'

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RAS: Astronomers Reveal a Cosmic 'Axis of Evil'

Post by bystander » Fri Jul 22, 2011 8:24 pm

Astronomers Reveal a Cosmic 'Axis of Evil'
Royal Astronomical Society | 2011 June 30
Astronomers are puzzled by the announcement that the masses of the largest objects in the Universe appear to depend on which method is used to weigh them. The new work was presented at a specialist discussion meeting on 'Scaling Relations of Galaxy Clusters' organised by the Astrophysics Research Institute (ARI) at Liverpool John Moores University and supported by the Royal Astronomical Society.

Clusters of galaxies are the largest gravitationally bound objects in the Universe containing thousands of galaxies like the Milky Way and their weight is an important probe of their dark matter content and evolution through cosmic time. Measurements used to weigh these systems carried out in three different regions of the electromagnetic spectrum: X-ray, optical and millimetre wavelengths, give rise to significantly different results.

Eduardo Rozo, from the University of Chicago, explained that any two of the measurements can be made to fit easily enough but that always leaves the estimate using the third technique out of line. Dubbed the 'Axis of Evil', it is as if the Universe is being difficult by keeping back one or two pieces of the jigsaw and so deliberately preventing us from calibrating our weighing scales properly.

More than 40 of the leading cluster astronomers from UK, Europe and the US attended the meeting to discuss the early results from the Planck satellite, currently scanning the heavens at millimetre wavelengths, looking for the smallest signals from clusters of galaxies and the cosmic background radiation in order to understand the birth of the Universe. The Planck measurements were compared with optical images of clusters from the Sloan Digitised Sky Survey and new X-ray observations from the XMM-Newton satellite.

ARI astronomers are taking a leading role in this research through participation in the X-ray cluster work and observations of the constituent galaxies using the largest ground-based optical telescopes.

One possible resolution to the 'Axis of Evil' problem discussed at the meeting is a new population of clusters which is optically bright but also X-ray faint. Dr Jim Bartlett (Univ. Paris), who is one of the astronomers who presented the Planck results, argued that the prospect of a new cluster population which responds differently was a 'frightening prospect' because it overturns age old ideas about the gravitational physics being the same from cluster to cluster.

Chris Collins, LJMU Professor of Cosmology, who organised the meeting said: '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. The results presented are unexpected and all three communities (optical, X-ray and millimetre) will need to work together in the future to figure out what is going on.'
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alive to the gentle breeze of communication, and please stop being such a jerk.
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Re: RAS: Astronomers Reveal a Cosmic 'Axis of Evil'

Post by bystander » Fri Sep 23, 2011 5:10 pm

Gravitational Waves Can Explain Dark Energy And Axis of Evil
Technology Review | Physics arXiv Blog | kfc | 2011 Sept 22
Cosmos-sized gravitational waves would distort our view of the universe in a way that matches some of cosmologists' most puzzling observation, says cosmologist

Here's an interesting idea that could explain some of the more puzzling features of our universe.

Cosmologists have long found evidence that the universe began in a big bang event and then expanded equally in all directions to become the cosmos we see today. They can see that distant galaxies are moving away from us, suggesting that the universe is expanding, and they can even see the echo of the big bang that caused this expansion.

That this echo seems evenly distributed around us has helped to back up the idea that we live in an ordinary part of the Universe that is more or less the same as every other part.

Neat and simple!

But in recent years, a number of strange observations have begun to make cosmologists think again. First, they've discovered that the universe is not just expanding but accelerating away form us. The evidence comes from observations of distant supernovas. And second, they've found that a closer examination of the echo of the big bang shows that it isn't evenly distributed at all but stronger in some directions than in others, the so-called Axis of Evil.

Nobody has come up for a satisfactory explanation of these observations, which leaves physicists in a bind. Not least because the observations imply that the universe is not more or less the same everywhere, that there are preferred directions and that the laws of physics may be different elsewhere in ways that are hard ot imagine and even more difficult to measure.

That's not so neat and not so simple.

Today, however, Edmund Schluessel at Cardiff University in Wales says that gravitational waves can explain all these observations. These are waves in the fabric of spacetime created by momentous events such as the collision of black holes and even the big bang itself.

Until now, cosmologists have considered only waves with relatively short wavelengths. But Schluessel's idea is to imagine what the universe would look like if it contained much bigger waves with a wavelength of the order of the curvature of the cosmos itself, that's some 10^10 light years. These would be waves left over from the big bang that continue to resonate slowly on a vast scale

Here's the thing. Schluessel says these waves would distort the microwave back ground radiation in way that matches the preferred directions cosmologists see today. What's more, it would also distort the light from distant objects in way that would make them look as if they were accelerating away.

Schluessel's conclusion is that "Strong long-scale gravitational waves can explain cosmic acceleration within the context of general relativity without resorting to the assumption of exotic forms of matter such as quintessence."

That's impressive given the contorted models that others have come up with. Schluessel even makes predictions about what the next generation of telescopes are likely to see if his model is correct. In particular, he says that more comprehensive surveys of distant supernovas should reveal the imprint of the waves. In other words, the waves should make the universe look as if it is accelerating more quickly in some directions that in others.

Time will tell. But in the meantime, Schluessel's model should give other cosmologists something to think about.

Long-wavelength gravitational waves and cosmic acceleration - Edmund R. Schluessel
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

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