The discovery using a telescope in Antarctica and ESA’s Herschel
space observatory, points the way towards finding evidence for
gravitational waves born during the universe’s rapid ‘inflation’ phase.
Astronomers have made the first detection of a subtle twist in the relic
radiation from the Big Bang, paving the way towards revealing the first
moments of the universe’s existence.
The elusive signal was found in the way the first light in the universe
has been deflected during its journey to Earth by intervening galaxy
clusters and dark matter, an invisible substance that is detected only
indirectly through its gravitational influence.
The discovery using a telescope in Antarctica and ESA’s Herschel space
observatory, points the way towards finding evidence for gravitational
waves born during the universe’s rapid ‘inflation’ phase.
The relic radiation from the Big Bang — the Cosmic Microwave Background,
or CMB — was imprinted on the sky when the Universe was just 380,000
years old.
Today, some 13.8 billion years later, we see it as a sky filled with
radio waves at a temperature of just 2.7 degrees above absolute zero.
Tiny variations in this temperature — around a few tens of millionths of
a degree — reveal density fluctuations in the early Universe
corresponding to the seeds of galaxies and stars we see today.
But the CMB also contains a wealth of other information.
A small fraction of the light is polarised, like the light we can see
using polarised glasses. This polarised light has two distinct patterns:
E-modes and B-modes.
E-modes were first found in 2002 with a ground-based telescope. B-modes,
however, are potentially much more exciting to cosmologists, although
much harder to detect.
They can arise in two ways. The first involves adding a twist to the
light as it crosses the Universe and is deflected by galaxies and dark
matter — a phenomenon known as gravitational lensing.
The second has its roots buried deep in the mechanics of a very rapid
phase of enormous expansion of the Universe, which cosmologists believe
happened just a tiny fraction of a second after the Big Bang —
‘inflation’
The new study has combined data from the South Pole Telescope and
Herschel to make the first detection of B-mode polarisation in the CMB
due to gravitational lensing.
“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 at
Urbana-Champaign.
