High level of precision measurement could unravel earliest secrets of the universe.
A team of 70 cosmologists operating under the name POLARBEAR has obtained the most accurate measurement yet of cosmic microwave polarization through use of a telescope in Chile’s Atacama desert.
Cosmic microwave background radiation is light left over from the Big Bang 13.8 million years ago. The universe expanded immediately after the Big Bang, causing the light to stretch into the microwave portion of the electromagnetic spectrum.
To obtain highly accurate measurements of this background radiation, the POLARBEAR group, led by UC San Diego Center for Astrophysics and Space Sciences researcher Kam Arnold, built super-sensitive instruments known as bolometers.
A bolometer, which looks at the direction of the light from different sections of the sky, is described by Arnold as “a map of all these little directions that the light’s electric field is pointing.” The new instrument enables scientists to view this light at an extremely high resolution, approximately three arcminutes, which amounts to one-tenth the size of the full Moon.
Such high resolution mapping also allows scientists to view what are known as B modes, which occur in polarization patterns. The presence of B modes is a sign the microwave light has been warped.
While the cause of such warping is unclear, some scientists attribute it to either neutrinos or dark matter.
Galactic dust, which also emits this type of polar radiation, can interfere with attempts to measure cosmic microwave background radiation. But in this case, Arnold said he and his team are confident that the three areas they studied are mostly dust-free.
“We are confident that these B modes are cosmological rather than galactic in origin,” Arnold said.
He views this latest and most accurate measurement of cosmic microwave polarization as an important milestone in understanding of the early universe. A report of the study is published in the Astrophysical Journal October 20 issue.
The researchers plan to follow up by expanding the map of cosmic microwave polarization using the telescopes of the Simon Array.
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