A map detailing the oldest light in our Universe has been released by the European Space Agency (ESA), revealing previously unknown features that “challenge the foundations of our current understanding of the Universe”.
The incredible image is based on 15 and a half months of data captured by ESA’s Planck space telescope, whose mission it is to study relic radiation left over from the Big Bang. Planck, which observes wavelengths between 0.3mm and 11.1mm (broadly covering the far-infrared, microwave, and high frequency radio domains), has been able to construct the most accurate picture to date of cosmic microwave background (CMB) — providing cosmologists and astronomers with new insights into the evolution of the Universe since its “birth” 13.82 billion years ago.
Planck has been detecting the tiny temperature fluctuations of CMB that scientists believe were imprinted shortly after the birth of the Universe, around 380,000 years after the Big Bang. By reading these temperature fluctuations, Planck is able to reveal the slightly different densities in the fabric of the Universe, that eventually became stars and galaxies.
An immediate result of the new image is that it confirms the standard model of cosmology used by scientists to describe the fundamental traits of our Universe.
“Since the release of Planck’s first all-sky image in 2010, we have been carefully extracting and analysing all of the foreground emissions that lie between us and the Universe’s first light, revealing the cosmic microwave background in the greatest detail yet,” explained George Efstathiou of the University of Cambridge. As well as providing “excellent confirmation” of the standard model of cosmology at an “unprecedented accuracy”, this latest image also improves our understanding of some previously held theories. Foremost is the suggestion that the Universe is expanding more slowly than previously thought (at 67.15 kilometres per second per megaparsec to be precise), and is actually 100 million years older than former estimates.
Another surprising find revealed by the new map is an asymmetry in the average temperatures found on opposite hemispheres of the Universe. Previously, the standard model of cosmology supposed that the Universe was homogeneous and isotropic, appearing to have similar properties at most points. In addition to this newly found temperature difference is the confirmation of a cold spot, previously noticed by Nasa’s Wilkinson Microwave Anisotropy Probe (WMAP), a predecessor to ESA’s Planck. When launched in 2001, WMAP detected the cold spot around the constellation Eridanus, but questions over the quality of the data meant that it was largely ignored. This cold spot is actually much larger than previously thought, and could well indicate that light rays from the CMB have taken a far more complicated route through the Universe than previously thought.
“The fact that Planck has made such a significant detection of these anomalies erases any doubts about their reality; it can no longer be said that they are artefacts of the measurements. They are real and we have to look for a credible explanation,” said Paolo Natoli of the University of Ferrara, Italy. This could see cosmologists going back to the drawing board to work out why light has travelled through this cold spot in such a way.
The map has also shed new light on our understanding of what the Universe is made up of. Ordinary matter, which makes up stars and galaxies, contributes to 4.9 percent of the mass/energy density of the Universe — 0.4 percent more than previously thought. The amount of dark matter has also increased over previous estimates, now thought to be 26.8 percent of the total mass of the Universe, up from 22.7 percent. Dark energy, the “mysterious force” thought to be responsible for accelerating the expansion of the Universe, makes up the remaining 68.3 percent of cosmic recipe.
“With the most accurate and detailed maps of the microwave sky ever made, Planck is painting a new picture of the Universe that is pushing us to the limits of understanding current cosmological theories,” said Jan Tauber, ESA’s Planck Project scientist.
The ESA will publish a series of scientific papers describing the new results on 22 March, in which Planck’s findings will further clarify our understanding of the standard model of cosmology.