Planck unveils wonders of the Universe
The first scientific results from Europe’s Planck spacecraft were released at a press briefing today in Paris. The findings, focusing on the coldest objects in the Universe - both within our Galaxy and also out to the most distant reaches of space - include an exciting variety of astronomical finds, from massive galaxy clusters to new, unidentified objects. Planck is a flagship mission of the UK Space Agency, which funds the UK’s involvement in both of Planck’s scientific instruments. Astronomers from around the UK are now heavily involved in the operation of Planck’s two scientific instruments and in understanding the images and data it is now producing.
Dr David Parker, Director of Space Science and Exploration for the UK Space Agency, said, “We’re proud to be playing a key role in this amazing discovery machine. These new results are all vital pieces of a jigsaw that could give us a full picture of the evolution of both our own cosmic backyard – the Milky Way galaxy that we live in – as well as the early history of the whole Universe.”
A patch of sky around 100 times the size of the Full Moon, showing the distant population of galaxies. Image credit: ESA/Planck consortium
The routine phase of Planck’s mission began on 13th August 2009. The observatory’s primary goal is to image the Cosmic Microwave Background, the afterglow of the Big Bang, but to do so it must look through the rest of the Universe. Whist scanning the whole sky, Planck detects emission from our own Galaxy, the Milky Way, as well as from other galaxies. It does not see stars, however, but the gas and dust from which the stars are born, and which they create when they die.
Prof. George Efstathiou, University of Cambridge and member of the Planck Science Team, said “Planck was designed intentionally to have a wide scientific reach, extending well beyond its primary scientific goal of investigating the very first moments after the Big Bang. Planck's scientific diversity is striking in this first release of scientific results. There are new discoveries on dust and cold gas in our Galaxy, star forming regions, very distant galaxies and clusters of galaxies. These early results provide just a first glimpse of Planck's scientific potential. I expect much more to come in the next two years.”
The new results include evidence for an otherwise invisible population of galaxies shrouded in dust billions of years in the past, which formed stars at rates some 10–1000 times higher than we see in our own Galaxy today. Measurements of this population had never been made at these wavelengths before. In order to see it properly, contaminating emission from a whole host of foreground sources must first be removed.
Today, an important step towards removing this contamination was also announced. The ‘anomalous microwave emission’ is a diffuse glow most strongly associated with the dense, dusty regions of our Galaxy, but its origin has been a puzzle for decades.
One of the areas of the Galaxy where Planck has seen the anomalous microwave emission. Image credit: ESA/Planck consortium.
However, data collected by Planck confirm the theory that it is coming from dust grains spinning at several tens of billions times a second by collisions with either fast-moving atoms or packets of ultraviolet light. This new understanding helps to remove this local microwave ‘fog’ from the Planck data with greater precision, leaving the cosmic microwave background untouched. “This is a great result made possible by the exceptional quality of the Planck data,” says Dr Clive Dickinson, University of Manchester.
One of the advantages of Planck’s broad wavelength coverage is that it can detect very cold dust both within our Galaxy and beyond. Cold clumps of dust in our Galaxy, of which Planck has found over 900, represent the first stages of starbirth.
A survey of around 500 galaxies within a few billion light years has shown that some of them contain much more cold dust than previously thought. “Planck will help us to build a ladder connecting our Milky Way to the faint, distant galaxies and uncovering the evolution of dusty, star forming galaxies throughout cosmic history,” says Dr David Clements, Imperial College London.
Among the many other results presented today, Planck has also collected new data on clusters of galaxies – the largest structures in the Universe, each containing thousands of galaxies. These show up in the Planck data as compact silhouettes against the cosmic microwave background. By surveying the whole sky, Planck stands the best chance of finding the most massive examples of these clusters. They are rare and their number is a sensitive probe of the kind of Universe we live in, how fast it is expanding, and how much matter it contains.
The Planck mission has been in development for over 15 years, leading up to its launch in May 2009. “We could hardly imagine this point when we were building amplifiers for the Low Frequency Instrument at Jodrell Bank over 5 years ago. It is fantastic to have reached the stage where we see real science emerging," says Dr Althea Wilkinson, University of Manchester. Prof. Peter Ade, Cardiff University, who works on the High Frequency Instrument, added: “seeing these excellent results gives a glimpse of the legacy the Planck mission will provide in terms of the understanding our understanding of the Universe.”
Planck continues to survey the Universe. Its next data release is scheduled for January 2013 and will reveal the cosmic microwave background in unprecedented detail, the opening act of the cosmic drama, a picture of the beginning of everything.