POLARBEAR, a team of about 70 international scientists, have successfully recorded the most sensitive and accurate measurement of the cosmic microwave background (CMB) polarization. It will help them uncover the mysteries of the dark energy and dark matter, determine the mass of neutrinos, and map the large-scale structure of the universe. POLARBEAR published it study in The Astrophysical Journal.
CMB carries an imprint of the cosmic history
Led by Adrian Lee of the University of California at Berkeley, POLARBEAR is studying the remnant radiation from the Big Bang, which has stretched to microwave lengths with the expansion of the universe. The CMB acts as an enormous backlight, carrying an imprint of the cosmic history and illuminating the large-scale structure of the universe. Scientists used microwave detectors that can capture the oldest light in the universe. The detectors were mounted on the Huan Tran Telescope high in Atacama Desert of Chile.
POLARBEAR isolated the “B-mode” pattern produced by gravitational lensing during polarization of the CMB. Scientists have primarily focused on interpreting the polarization pattern of CMB to map distribution of matter during the universe’ inflationary period, which dates back to about 380,000 years after Big Bang. Gravitation waves were created by a rapid but very brief expansion of the universe just split-seconds after the Big Bang.
POLARBEAR detected B-mode produced through distortion of E-mode
The universe was formed about 13.8 billion years ago. At the time, the universe was so dense and hot that light bounced from one particle to another endlessly, ionizing the atoms that formed. After about 380,000 years, it cooled sufficiently to let a proton and an electron form a hydrogen atom. And then, all the photons were set free.
These photons still have information about their last interaction, according to the University of California. They have certain polarization (called E-mode polarization) due to the flow of matter driven by density fluctuations where they last scattered. E-mode could be converted into B-mode when light passes through gravitational fields of large objects such as clusters of galaxies. B-mode polarization contains a lot more information than E-mode.