First Detection of Curled Ripples in the Cosmic Background

The universe was created 13.73 billion years ago in a blaze of light: the big bang. Roughly 380,000 years later, after matter (mostly hydrogen) had cooled enough for neutral atoms to form, light was able to traverse space freely. That light, the cosmic microwave background radiation, comes to us from every direction in the sky uniformly ... or so it first seemed. In the last decades, astronomers discovered that the radiation actually has very faint ripples and bumps in it at a level of brightness of only a part in one hundred thousand. These miniscule ripples reflect the architecture of the universe when the light was freed, and allowed the formation of the subsequent cosmic structures (galaxies and clusters of galaxies) as the light passed by them on its journey through space and time. The ripples hold clues, therefore, to the early universe and how it has evolved, and are consequently among the top priorities of modern astronomy research.

Astronomers have speculated that these ripples should also contain traces of the postulated, fantastic, initial burst of expansion of the universe -- the so-called inflation -- that swelled the new universe by a factor of roughly ten-to-the-power 33 in a mere ten-to-the-power-minus-33 seconds. After the flash of inflation, the cosmos expanded (and continues to expand) at a much more leisurely pace, with the first neutral atoms forming hundreds of thousand of years later. According to theory, remnant clues about the inflation should be faintly present in the way the cosmic ripples are curled. Indeed, one of the "holy grails" of modern cosmology has been the detection of such curling, an effect that is expected to be perhaps one hundred times fainter than the ripples themselves. The effect is called the "B-mode polarization." Needless to say there are other exotic processes at work that make this daunting task even more challenging, in particular the role of gravity. Because gravity bends light (as Einstein predicted), cosmic matter will distort the light from the ripples and can do so in a way that also produces a curled signature.

CfA astronomer Tony Stark has joined with a large team of astronomers to make the pioneering first detection of curled ripples in the cosmic background - the long sought B-mode polarization signature. In a paper to appear in Physical Review Letters, the scientists announce the measurement of gravitationally-produced curling using a new microwave instrument on the South Pole Telescope. The team used a variety of tests and cross-checks to confirm their conclusions, which now open the way into the mysterious period of inflation itself. Although the postulated model of inflation has been hugely successful in predicting aspects of the universe, it is also somewhat controversial and relies on concepts in particle physics, quantum theory and even gravity that are not fully self-consistent and still under development. The curling ripples of creation, now finally discovered, should have an important impact on many fundamental fields of astronomy and physics.

"Detection of B-Mode Polarization in the Cosmic Microwave Background with Data from the South Pole Telescope," D. Hanson, S. Hoover, A. Crites, P. A. R. Ade, K. A. Aird, J. E. Austermann, J. A. Beall A. N. Bender,B. A. Benson, L. E. Bleem, J. J. Bock, J. E. Carlstrom, C. L. Chang, H. C. Chiang, H-M. Cho, A. Conley, T. M. Crawford, T. de Haan, M. A. Dobbs, W. Everett, J. Gallicchio, J. Gao, E. M. George, N.W. Halverson, N. Harrington, J.W. Henning, G. C. Hilton, G. P. Holder, W. L. Holzapfel, J. D. Hrubes, N. Huang, J. Hubmayr, K. D. Irwin, R. Keisler, L. Knox, A. T. Lee,E. Leitch, D. Li, C. Liang, D. Luong-Van, G. Marsden, J. J. McMahon, J. Mehl, S. S. Meyer, L. Mocanu, T. E. Montroy, T. Natoli, J. P. Nibarger, V. Novosad, S. Padin, C. Pryke, C. L. Reichardt, J. E. Ruhl, B. R. Saliwanchik, J. T. Sayre, K. K. Schaffer, B. Schulz, G. Smecher, A. A. Stark, K. T. Story, C. Tucker, K. Vanderlinde,J. D. Vieira, M. P. Viero, G. Wang, V. Yefremenko, O. Zahn, and M. Zemcov, PRL, 111, 141301, 2013.