Magnetic fingerprint of our galaxy revealed

Researchers have created a map using data from the Planck Space Telescope.

Since 2009, Planck has charted the Cosmic Microwave Background (CMB), the light from the Universe a mere 380,000 years after the Big Bang.

But Planck also observes light from much closer than the farthest reaches of time and space. With an instrument called the High Frequency Instrument (HFI), Planck detects the light from microscopic dust particles within our Galaxy. (The density of this dust is incredibly low; a volume of space equal to a large sports stadium or arena would contain one grain.)

Planck's HFI identifies the non-random direction in which the light waves vibrate-known as polarization. It is this polarized light that indicates the orientation of the field lines.

"Just as the Earth has a magnetic field, our Galaxy has a large-scale magnetic field-albeit 100,000 times weaker than the magnetic field at the Earth's surface," says team member Prof. Douglas Scott (UBC). "And just as the Earth's magnetic field generates phenomena such as the aurorae, our Galaxy's magnetic field is important for many phenomena within it."

"And now," says Scott, "Planck has given us the most detailed picture of it yet."

Prof. Peter Martin (CITA) uses Planck data to study the dust found throughout our Galaxy.

According to Martin, "Dust is often overlooked but it contains the stuff from which terrestrial planets and life form. So by probing the dust, Planck helps us understand the complex history of the Galaxy as well as the life within it."

The Planck data will enable a much more detailed investigation of the early history of the cosmos, from the accelerated expansion when the Universe was much less than one second old to the period when the first stars were born, several hundred million years later.

The "fingerprint" and other results are described in four papers to be published in the journal Astronomy and Astrophysics.