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Dr. Torsten Enßlin

Max Planck Institute for Astrophysics, Garching
Phone:+49 89 30000-2243

Dr. Hannelore Hämmerle

Max Planck Institute for Astrophysics, Garching
Phone:+49 89 30000-3980Fax:+49 89 30000-3569

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<p>In its first year in operation, the “Planck Surveyor” satellite has achieved impressive results: a catalogue with 15,000 celestial objects such as galaxy clusters, quasars, radio galaxies, nearby galaxies and galactic dust clouds, 25 scientific papers, as well as the most precise measurement of the far infrared background to date, which reveals star formation in the early universe.</p>

15,000 new celestial objects

January 13, 2011

In its first year in operation, the “Planck Surveyor” satellite has achieved impressive results: a catalogue with 15,000 celestial objects such as galaxy clusters, quasars, radio galaxies, nearby galaxies and galactic dust clouds, 25 scientific papers, as well as the most precise measurement of the far infrared background to date, which reveals star formation in the early universe.

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<p>Researchers at the Max Planck Institute for Astrophysics prepare scientific projects for the upcoming mission</p>

Planck Satellite ready to measure the Big Bang

May 12, 2009

Researchers at the Max Planck Institute for Astrophysics prepare scientific projects for the upcoming mission

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Astrophysics

Planck reveals an almost perfect Universe

Planck measures the Universe - detailed all-sky map of the cosmic background radiation confirms standard cosmological model but also finds deviations

March 21, 2013

On 21 March 2013 the Planck collaboration presented its first all-sky map of the cosmic microwave background radiation, which impressively confirms the standard model of cosmology and determines its parameters more accurately than ever before. At the same time, the researchers also found significant anomalies and inhomogeneities indicating that some aspects of the "standard model" are not yet understood.
The anisotropies of the Cosmic microwave background (CMB) as observed by Planck. The CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380,000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today. Zoom Image
The anisotropies of the Cosmic microwave background (CMB) as observed by Planck. The CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380,000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today. [less]

The all-sky map released now is based on the first 15.5 months of observations with the Planck space telescope, a mission of the European Space Agency (ESA), and shows the oldest light in the universe. This was emitted when the universe was only 380,000 years old and became transparent for the first time after the Big Bang. The "primordial soup" of protons, electrons and photons cooled gradually, allowing neutral hydrogen atoms to form and the light to escape. As the universe continued to expand and to cool, this radiation was shifted to longer wavelengths, so that it is received today as the cosmic microwave background (CMB) at a temperature of about 2.7 Kelvin.

Tiny temperature fluctuations in this CMB map reflect smallest density fluctuations in the early universe. "The Planck CMB map provides us with an extremely detailed picture of the very early universe," said Simon White, Co-Investigator in the Planck Collaboration and director at the Max Planck Institute for Astrophysics (MPA), who helped to establish the standard model of cosmology in the 1980s by analysing the evolution of structure in the universe. “All the structures that we see today grew from tiny density fluctuations shortly after the Big Bang.”

Planck was designed to measure these fluctuations across the whole sky with greater resolution and sensitivity than ever before, allowing scientists to determine the composition and evolution of the universe from its birth to the present day.

"The Planck data fit extremely well with the standard model of cosmology," says Torsten Enßlin of the MPA, who is managing Germany's participation in the Planck mission. "The cosmological parameters have been refined with Planck more accurately than ever, and our analysis passed all tests against various other astronomical observations with flying colours."

The analysis of the Planck data show that normal matter, making up galaxies, stars and also Earth, contribute only about 4.9% to the mass and energy density of the universe. About 26.8% is dark matter, which interacts only through its gravitational effect – contributing far more than previously assumed. Dark energy, the mysterious component that causes the universe to expand ever faster, on the other hand, accounts for only 68.3%, less than expected.

This graph shows the temperature fluctuations in the Cosmic Microwave Background detected by Planck at different angular scales on the sky. This curve is known as the power spectrum. The largest angular scales, starting at angles of ninety degrees, are shown on the left side of the graph, whereas smaller and smaller scales are shown towards the right. (For comparison, the diameter of the full Moon in the sky measures about half a degree.) The red dots correspond to measurements made with Planck; these are shown with error bars that account for measurement errors as well as for an estimate of the uncertainty that is due to the limited number of points in the sky at which it is possible to perform measurements. This so-called cosmic variance is an unavoidable effect that becomes most significant at larger angular scales. The green curve shown in the graph represents the best fit of the 'standard model of cosmology' – currently the most widely accepted scenario for the origin and evolution of the Universe – to the Planck data. The pale green area around the curve shows the predictions of all the variations of the standard model that best agree with the data. Zoom Image
This graph shows the temperature fluctuations in the Cosmic Microwave Background detected by Planck at different angular scales on the sky. This curve is known as the power spectrum. The largest angular scales, starting at angles of ninety degrees, are shown on the left side of the graph, whereas smaller and smaller scales are shown towards the right. (For comparison, the diameter of the full Moon in the sky measures about half a degree.) The red dots correspond to measurements made with Planck; these are shown with error bars that account for measurement errors as well as for an estimate of the uncertainty that is due to the limited number of points in the sky at which it is possible to perform measurements. This so-called cosmic variance is an unavoidable effect that becomes most significant at larger angular scales. The green curve shown in the graph represents the best fit of the 'standard model of cosmology' – currently the most widely accepted scenario for the origin and evolution of the Universe – to the Planck data. The pale green area around the curve shows the predictions of all the variations of the standard model that best agree with the data. [less]

Finally, the Planck data also set a new value for the rate at which the Universe is expanding today, known as the Hubble constant. At 67.15 km/s/Mpc, this is significantly less than the current standard value in astronomy. The data imply that the age of the Universe is 13.82 billion years.

However, because the precision of Planck’s map is so high, it also revealed some peculiar unexplained features, which cannot easily be reconciled with the standard model. One of the most surprising findings is that the fluctuations in the CMB temperatures at large angular scales are not as strong as expected from the smaller scale structure revealed by Planck. Another is an asymmetry in the average temperatures on opposite hemispheres of the sky. This runs counter to the prediction made by the standard model that the Universe should be broadly similar in any direction we look. Furthermore, a cold spot extends over a patch of sky that is much larger than expected. This data could point to an extension of the standard model or even new theories. “But even if we do not yet understand these anomalies, we can eliminate the possibility that they are due to foreground effects,” says Torsten Enßlin. “The ‘cold spot’, in particular, has been known for quite a while and could well be a statistical fluctuation.”

The MPA scientists have been involved in software development even from before the beginning of the mission, to process the data and remove foreground emission from objects such as galaxies, quasars, and even our own Milky Way. By now, their work focuses on analysing information from the cosmic microwave background radiation and trying to better understand our universe.

One aspect, amongst many others, is the discovery and measurement of galaxy clusters by the Sunyaev-Zel'dovich effect. The SZ effect is a characteristic signature imprinted by galaxy clusters on the cosmic microwave background, when the light from the CMB passes through the cluster. Because of the different frequency bands available with Planck, the SZ effect can be used as a unique tool for detecting galaxy clusters.

Rashid Sunyaev, Co-Investigator in the Planck Collaboration and director at the Max Planck Institute for Astrophysics, together with Yakov Zel'dovich predicted not only the effect of galaxy clusters on the CMB but also the existence of the acoustic peaks in the CMB itself which Planck has now measured so precisely. He is excited by the Planck results: "When we developed our models of the CMB radiation more than 40 years ago, we thought of it mainly as a theoretical thought experiment. It is amazing that the measurements are now so detailed that it can even be used as tool to discover hundreds of new galaxy clusters that where unknown before. A great success for Planck!”

Planck scientists were even able to use this sample of clusters of galaxies to derive key parameters of the universe – a method that has been employed with CMB data for the first time. This is an additional a completely independent method from the way which uses the shape and amplitude of the acoustic peaks.

 
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