Planck All-Sky Images Show Cold Gas and Strange Haze

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Whitney Clavin 818-354-4673
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Markus Bauer +31 71 565 6799
European Space Agency
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Image advisory: 2012-040 Feb. 13, 2012

Planck All-Sky Images Show Cold Gas and Strange Haze

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2012-040&cid=release_2012-040

New images from the Planck mission show previously undiscovered islands of star formation
and a mysterious haze of microwave emissions in our Milky Way galaxy. The views give
scientists new treasures to mine and take them closer to understanding the secrets of our galaxy.

Planck is a European Space Agency mission with significant NASA participation.

"The images reveal two exciting aspects of the galaxy in which we live," said Planck scientist
Krzysztof M. Gorski from NASA's Jet Propulsion Laboratory in Pasadena, Calif., and Warsaw
University Observatory in Poland. "They show a haze around the center of the galaxy, and cold
gas where we never saw it before."

The new images show the entire sky, dominated by the murky band of our Milky Way galaxy.
One of them shows the unexplained haze of microwave light previously hinted at in
measurements by NASA's Wilkinson Microwave Anisotropy Probe (WMAP).

"The haze comes from the region surrounding the center of our galaxy and looks like a form of
light energy produced when electrons accelerate through magnetic fields," said Davide
Pietrobon, another JPL Planck scientist.

"We're puzzled though, because this haze is brighter at shorter wavelengths than similar light
emitted elsewhere in the galaxy," added Gorski.

Several explanations have been proposed for this unusual behaviour.

"Theories include higher numbers of supernovae, galactic winds and even the annihilation of
dark-matter particles," said Greg Dobler, a Planck collaborator from the University of California
in Santa Barbara, Calif. Dark matter makes up about a quarter of our universe, but scientists don't
know exactly what it is.

The second all-sky image is the first map to show carbon monoxide over the whole sky. Cold
clouds with forming stars are predominantly made of hydrogen molecules, difficult to detect
because they do not readily emit radiation. Carbon monoxide forms under similar conditions, and
though it is rarer, the gas emits more light. Astronomers can use carbon monoxide to identify the
clouds of hydrogen where stars are born.

Surveys of carbon monoxide undertaken with radio telescopes on the ground are time-
consuming, so they are limited to portions of the sky where clouds of molecules are already
known or expected to exist. Planck scans the whole sky, allowing astronomers to detect the gas
where they weren't expecting to find it.

Planck's primary goal is to observe the Cosmic Microwave Background, the relic radiation from
the Big Bang, and to extract its encoded information about what our universe is made of, and the
origin of its structure.

This relic radiation can only be reached once all sources of foreground emission, such as the
galactic haze and the carbon monoxide signals, have been identified and removed.

"The lengthy and delicate task of foreground removal provides us with prime datasets that are
shedding new light on hot topics in galactic and extragalactic astronomy alike," said Jan Tauber,
Planck project scientist at the European Space Agency.

Planck's first findings on the Big Bang's relic radiation are expected to be released in 2013. The
new results are being presented this week at an international astronomy conference in Bologna,
Italy.

NASA's Planck Project Office is based at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
JPL contributed mission-enabling technology for both of Planck's science instruments. European,
Canadian and U.S. Planck scientists will work together to analyze the Planck data. More
information is online at http://www.nasa.gov/planck and http://www.esa.int/planck .

JPL is managed for NASA by the California Institute of Technology in Pasadena.

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