Planck Reveals Hidden Riches of the Cosmos

Canadian astronomers help create unprecedented survey of the Universe

Less than two years on the job and the Planck space telescope has uncovered a treasure trove of strange and mysterious objects scattered across the Universe that will keep astronomers busy for years to come.

Canadians are part of an international scientific team that has been pouring over a new survey of the entire sky taken in microwave wavelengths by Planck, a mission launched in 2009 by the European Space Agency and supported by the Canadian Space Agency. They have assembled a unique catalogue of thousands of new objects ranging from some of the largest structures in the Universe–clusters of galaxies–to the very smallest: cold dust, the actual building blocks that help form new generations of stars.

This animation illustrates the position on the sky of all foreground objects detected by Planck during its first all-sky survey and how they compare to the microwave view of the sky as seen by Planck. The size of the spots displayed in the series of images reflects the brightness of the sources.

Data from Planck has been used to compile a catalogue containing a wide variety astronomical objects, both galactic (features in the galactic interstellar medium, cold molecular cloud cores, stars with dust shells) and extragalactic (radio galaxies, blazars, infrared-luminous galaxies, and galaxy clusters).
Credit: ESA/ Planck Collaboration

Planck's mission is to capture the heat left behind from the birth of our Universe, known as the Cosmic Background Radiation. This ancient light is considered the radiation echo of the Big Bang that has weakened and shifted toward the faint infrared and microwave parts of the spectrum.

Planck's supersenstivity to microwaves has allowed it to detect 189 gigantic clusters of galaxies, including 20 that have never been seen before. When this ancient shockwave of microwave background travels through a cluster of galaxies, it shifts the energy levels of the radiation, leaving behind a distinctive spectral signature that Planck can see. Hopes are now high that this new hunting technique will lead to the discovery of thousands of clusters, which could shed light on the overall structure and evolution of the Universe.

By mapping the sky in these longest of wavelengths (beyond what the human eye can see), Planck is also providing a detailed and first-of-its-kind inventory of a menagerie of foreground structures–cosmic stuff in the foreground of this relic radiation emitted some 13 billion years ago.

Among the most peculiar finds include the presence of extremely rapidly spinning dust grains scattered across the star-forming regions of the Milky Way and neighbouring satellite galaxies. They not only emit microwaves like most other dust encountered so far, but they also send out radiowaves as they spin. Astronomers are now grappling to understand how the smallest dust grains in the Universe, made up of only 10 to 50 atoms, can rotate 10 billion times a second!

Another Planck discovery puzzling astronomers is something called "dark gas," a new type of molecular gas found clinging to the edges of giant molecular clouds within the Milky Way. Dark gas may have an impact on galaxy formation and evolution.

In this most detailed survey of cold dust in and around the Milky Way ever conducted,. Planck has also catalogued nearly a thousand clumps of gas and dust, dubbed "cold cores," that are scattered across our local stellar neighbourhood. The coldest known objects in the Universe, cold cores are star factories in the making, and as such will play a key role in our understanding of the very earliest stages of star birth.

"We have never had an all-sky survey at these frequencies and resolutions before," said Douglas Scott, University of British Columbia professor and Canadian investigator for Planck mission. "So there are literally thousands of objects that we are beginning to see for the first time, many which we don't exactly yet know what they are."

The Planck Space Telescope mission is led by the European Space Agency, and includes contributions from the Canadian Space Agency (CSA). The CSA funds two Canadian research teams that are part of the Planck science collaboration, and who participated in the development of both of Planck's science instruments, the Low Frequency Instrument (LFI) and the High Frequency Instrument (HFI). Professor Douglas Scott of the University of British Columbia is leading the Canadian LFI team. The HFI team is led by Professor J. Richard Bond of the University of Toronto.