University of Toronto astronomers are in Paris this week as part of an international conference announcing the first scientific results of the Plank space telescope mission.
Launched in May 2009, the telescope has nearly completed three of its four planned surveys of the entire sky, providing astronomers a glimpse of conditions near the beginning of the Universe and providing data that will help answer the big questions: How was the Universe formed? How has it evolved to its present form? And what shape will it take in future?
“Planck has worked flawlessly to give us unprecedented all-sky coverage of the emission by cosmic dust, giving us for the first time insight into dust evolution in different environments from the most diffuse to the dense molecular regions in which new stars are forming,” says U of T astronomer Peter Martin, one of the Planck scientists. “Because dust is the reservoir holding the essential materials from which terrestrial planets and life ultimately form, this is welcome progress toward understanding our complex history.”
The most sensitive telescope ever designed to study the cosmic microwave background — the remnants of radiation from the Big Bang some 13 billion years ago and the oldest source of light in the universe — Planck’s detectors measure the temperature of this light, searching for regions that are slightly warmer or colder than the average. These small fluctuations in temperature, called anisotropies, provided the seeds for the formation of galaxies that exist today.
The problem is that the radiation left over from the Big Bang is distorted by objects in the foreground, like galaxies, stars, gas and dust. The Planck team has produced a guidebook of 10,000 foreground objects that will become targets for future study, and charted new types of astrophysical structures:
- 189 gigantic clusters of galaxies, including 20 that have never been seen before;
- cold dust clouds where stars are forming, among the coldest ever discovered, and the first all-sky census;
- dark gas, a previously undetected type of molecular gas found clinging to the edges of giant molecular clouds in the Milky Way, and which may have an impact on galaxy formation and evolution; and,
- microwave emission from a population of tiny dust particles, or large molecules, that spin up to ten billion times per second.
The Planck survey will help researchers trace the large-scale distribution of star-forming galaxies, as well as provide information about the still-unclear link between dark matter and star-forming galaxies. Some astronomers believe that dark matter may provide the skeleton for galaxies to form and evolve. The Planck catalogue will also shed new light on well known — but poorly understood — objects, like compact clumps of cold dust that string together to form huge filaments in our own galaxy, the Milky Way. These extremely cold objects may hold clues to the history of how stars form.
University of Toronto scientists have played a key role on the High Frequency Instrument (HFI), an ultra-sensitive instrument cooled to a fraction of a degree above absolute zero to detect minute cosmic signals. It is one of two instruments on board, the other Low Frequency Instrument (LFI) involves scientists at UBC. Both receive the radiation captured by the satellite’s 1.5 metre mirror. Essential software to analyze the HFI signals was developed by a team at U of T led by J. Richard Bond of the Canadian Institute for Theoretical Astrophysics and Barth Netterfield of the Departments of Astronomy and Astrophysics and of Physics to enable rapid verification of the data as it comes from the satellite and its subsequent analysis. This software has also been developed for use by the LFI by the UBC team. The LFI and the HFI complement each other to analyze the light gathered during the microwave surveys of the sky. These two cameras cover different areas of the light spectrum. The LFI operates like a transistor radio and the HFI converts the electromagnetic radiation into heat for subsequent analysis.
The Canadian teams have spent more than a decade working with their international colleagues to plan for the Planck mission, and are directly involved in using the data to answer some of the biggest questions in the Universe. Twenty-five scientific papers have been produced in the first two years of operation of the European space observatory, with U of T/CITA scientists serving as authors on the majority of papers. Peter Martin of CITA was chosen to present the overview talk in Paris on cosmic dust in the Milky Way Galaxy to introduce the exciting Planck results on these ubiquitous tiny grains. University Professor J. Richard Bond was chosen to put the discoveries by Planck announced today on huge clusters of galaxies by the scattering of the cosmic background radiation from hot high-pressure gas in the clusters. He was also chosen to end the conference with his summary of the scientific import of the remarkable results presented by Planck.
“There is a gorgeous composite image of all of the sky as it appears to Planck, showing the structure in the first light of the Universe when it was released some 380000 years after the Big Bang,” says Bond. But there is also a set of veils in front hiding this pristine snapshot of the earliest moments we as humans can see. The veils are composed of emissions from our own Milky Way, and emissions from galaxies bursting in their birth with copious production of massive stars, radio waves powered by the huge gravitational energy of gigantic black holes in the centres of galaxies, and the heating of the first light by the largest entities in the Universe, the great clusters of galaxies and the superclusters they are invariably housed in.”
“We celebrate with our fellow Planckians that we have come so far since launch with this first release detailing the intricate nature of the veils. But it is the great cosmic mysteries of the what, where and why of the first moments of the Universe to behold once the veils are lifted that holds the ultimate fascination for me as a cosmologist and a Planckian. Stay tuned for that.”
Other U of T scientists in the Planck mission include: Marc Antoine Miville Deschenes, Mike Nolta and Jens Chluba of CITA, who are also in Paris for the Planck unveiling, and Francine Marleau of Astronomy and Astrophysics. The Planck Space Telescope mission is led by the European Space Agency. The Canadian Space Agency funds the two Canadian research teams who are part of the Planck science collaboration, and who participated in the development of both of Planck’s LFI and HFI science instruments. The Planck Space Telescope will continue to survey the Universe, with its next data release scheduled for January 2013.
J. Richard Bond