October 23, 2013
Twisted Path Of Ancient Light Finally Mapped
John P. Millis, PhD for redOrbit.com - Your Universe Online
When astronomers peer into the deepest regions of the cosmos they are not seeing the Universe as it exists today, but rather how it looked billions of years ago. That's because light emitted by distant galaxies moves at a finite speed and therefore requires billions of years to reach Earth.
Further complicating the matter is the fact that the light does not travel along a direct line of site to Earth. The photons are deflected by gravitational disturbances caused by the matter interwoven throughout space, creating a twisted path of light. This pattern of light, known as B-modes, has been sought after for decades, as researchers attempt to map the Universe.
But new work published September 30 in the online edition of Physical Review Letters, using the National Science Foundation’s South Pole Telescope, along with the Herschel Space Observatory, has finally been able to trace part of the B-modes – those which were produced a few billions years after the Big Bang.
However, the other class of B-modes – those created in the first moments after the Universe sprang into existence – remains elusive. "This latest discovery is a good checkpoint on our way to the measurement of primordial B-modes," said the study's lead author Duncan Hanson of McGill University in Montreal, Canada.
The scientists were searching for patterns of gravitational lensing – regions where light is bent around other galaxies and regions of dark matter – by looking for telltale polarizations of light. Because the light is traveling from such distant systems, the signals are incredibly faint, requiring the infrared capabilities of the Herschel observatory to sort through the noise.
Follow-up observations from the South Pole telescope revealed the locations of the B-modes, which will allow astronomers to more accurately map the location of galaxies and dark matter in the Universe.
"These beautiful measurements from the South Pole Telescope and Herschel strengthen our confidence in our current model of the universe," said Olivier Doré, a member of the US Planck science team at NASA's Jet Propulsion Laboratory in Pasadena, California. "However, this model does not tell us how big the primordial signal itself should be. We are thus really exploring with excitement a new territory here, and a potentially very, very old one."
Of course, this is only a first step. The much older B-modes could reveal clues about the Big Bang itself and allow researchers to better understand and trace the earliest moments of the Universe. The faint echo of the moment of creation still persists across the cosmos in the Cosmic Microwave Background (CMB), which researchers hope will provide the necessary vehicle to map the earlier B-modes.