New measurements confirm standard view of Universe
DR EMILY BALDWIN
Posted: November 03, 2009
An international team of astronomers has unveiled a new map of the seed structures of the Universe that support the standard model of cosmology and the existence of dark matter and dark energy.
The measurements were made using the Q U Extra-galactic Survey Telescope (QUEST) instrument located at the south pole, and were lead by Sarah Church of KIPAC (jointly located at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University), and by Walter Gear of Cardiff University. The instrument took measurements of the cosmic microwave background (CMB), the faint afterglow of the big bang from which our Universe was born, focusing on variations in the CMB’s temperature and polarization to shed light on the distribution of matter in the early Universe.The QUaD collaboration uses the 2.6-metre telescope (bottom) to view the temperature and polarization of the cosmic microwave background, a faintly glowing relic of the young Universe (top; colours indicate temperature deviations, black lines indicate polarization directions). Image: Nicolle Rager Fuller, NSF.
Polarization can be imagined as an extra direction to all light rays that is at right angles to the ray's direction of travel. Most light is unpolarized, that is, it consists of light rays with an equal mix of all polarizations, but reflection and scattering can create the 'glare' of polarized light (and which is blocked out by polarized sunglasses on a sunny day, for example).
Initially unpolarized light from the early Universe became polarized when it encountered moving matter. By creating maps of this polarization, the QUaD team was able to investigate not just where the matter existed, but also how it was moving, the most sensitive measurements of this kind ever made.
The results are very much in line with the temperature and polarization predicted by the existence of dark matter and dark energy in the standard cosmological model, which together make up 95 percent of everything in existence, while ordinary matter makes up just five percent.
“Microwave background observations are about the most technically challenging in contemporary astrophysics and cosmology,” says Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) Director Roger Blandford. “It is wonderful to see such solid measurements and such a clear confirmation of the theory.”
“When I first started in this field, some people were adamant that they understood the contents of the Universe quite well,” adds Church. “But that understanding was shattered when evidence for dark energy was discovered. Now that we again feel we have a very good understanding of what makes up the Universe, it’s extremely important for us to amass strong evidence using many different measurement techniques that this model is correct, so that this doesn’t happen again.”
The results are published in the 1 November issue of The Astrophysical Journal.
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