Observers using telescopes in Antarctica and the European Space Agency's Herschel Space Observatory found the signal of the "twist" in the way the first light in the universe has been deflected by intervening galaxy clusters and dark matter during its journey to Earth, ESA said in a news release Tuesday.
Dark matter is an invisible substance detectable only indirectly through its gravitational influence. The finding points toward evidence for gravitational waves born during the universe's early rapid "inflation" phase, astronomers said.
The relic radiation from the big bang, known as the Cosmic Microwave Background, or CMB, was imprinted on the sky when the universe was just 380,000 years old. Today, 13.8 billion years later, it exists as radio waves at a temperature of 2.7 degrees above absolute zero.
A small fraction of the CMB radiation is polarized, like the light seen through polarized eyeglass lenses, and that polarized light comes in two distinct patterns.
The first involves adding a twist to the radiation as it crosses the universe and is deflected by galaxies and dark matter -- a phenomenon known as gravitational lensing. The second has its origins in the mechanics of a very rapid phase of enormous expansion of the universe, and "inflation" cosmologists believe happened a tiny fraction of a second after the big bang.
Observations from the South Pole Telescope and the Herschel Space Observatory are the first to detect the pattern of polarization in the CMB due to gravitational lensing, the astronomers said.
"This measurement was made possible by a clever and unique combination of ground-based observations from the South Pole Telescope -- which measured the light from the big bang -- with space-based observations from Herschel, which is sensitive to the galaxies that trace the dark matter which caused the gravitational lensing," said Joaquin Vieira of the California Institute of Technology and the University of Illinois, who led the Herschel survey used in the study.