UCSB Cosmology Group

PLANCK

Planck is an international mission of NASA, the United States' National Aeronautics and Space Administration and ESA (and this is a link), the European Space Agency. Set to launch in April 2009, Planck will map the Cosmic Microwave Background (CMB) radiation of the universe in great detail, across nine frequency bands, as well as measure the polarization of the CMB.

Planck is the third generation of satellites to map the CMB, coming after the COBE and WMAP satellites. (and both of these are links to the appropriate web pages)

Here you will find information about the mission, as well as general information about cosmology, extracting information from the Power Spectrum of the CMB, and understanding what we can learn about the physics of the early universe by studying the polarization power spectrum of the CMB.

The PLANCK mission looks back at the very dawn of time ... to measure the the Cosmic Microwave Radiation of the Universe, the oldest light we can see, coming from a time when the Universe was somewhere between 300,000 and 400,000 years old - about 13 billion years ago. PLANCK will measure small temperature difference across the sky on the order of a few millionths of a degree. These temperature variations correspond to density variations in the earliest moments of the Universe. Thus, accurately measuring the cosmic background radiation can give us information about the very young Universe.

Planck will help us answer questions such as:

• How big and how old is the universe?

• What is the shape of space?

• We know that most of the matter in the Universe is in some "dark" form that we can't see, but we can detect from its gravity. What is this dark matter?

• We know the universe is expanding. But recently, we found that the rate of expansion is accelerating! What is the energy, behind this acceleration? Is it the "dark energy"? IF so, it would make up for 70% energy in the universe...

• How did the stars, galaxies and other objects as we see them, form?

• Did the universe (early stages) have a period of inflation (rapid expansion) ?

For more information about the Planck Mission, please visit:

The Official PLANCK Page at the European Space Agency

The NASA PLANCK Page at the Jet Propulsion Laboratory in Pasadena, California

In late 1992, the COBE team announced the detection of intrinsic temperature fluctuations in the Cosmic Background Radiation Field (CBRF), observed on the sky at angular scales larger than ~10°, and at a brightness level T/T~10^-5. More recently, in February 2003, the WMAP team announced results on scales of about 15 arcmin with a similar sensitivity. These fluctuations have been interpreted as due to differential gravitational redshift of photons scattered out of an inhomogeneously dense medium; they thus map the spectrum of density fluctuations in the Universe at a very early epoch. This long-sought result establishes the Inflationary Big Bang model of the origin and evolution of the Universe as the theoretical paradigm. However, in spite of the importance of the COBE and WMAP measurements, many fundamental cosmological questions remain open.

Building on the pioneering work of COBE and WMAP, the main objective of the Planck mission is to map the fluctuations of the CBRF with an accuracy that is set by fundamental astrophysical limits, allowing these fundamental questions to be effectively addressed. Mapping the fluctuations of the CBRF with high angular resolution and high sensitivity would give credible answers to such issues as:

• the initial conditions for structure evolution;

• the origin of primordial fluctuations;

• the type of potential that drove inflation;

• the existence of topological defects;

• the nature and amount of dark matter;

• and the nature of dark energy.

Planck will set constraints on theories of particle physics at energies higher than 1015 GeV, which cannot be reached by any conceivable experiment on Earth. Finally, the ability to measure to high accuracy the angular power spectrum of the CBRF fluctuations will allow the determination of fundamental cosmological parameters such as the density parameter "Omega" and the Hubble constant H0 with an uncertainty of only a few percent. The observational goal of the Planck mission is to mount a single space-based experiment to survey the temperature fluctuations across the whole sky with an angular resolution as high as 5 arcmin, a sensitivity approaching 1 part in 106, and covering a frequency range that is wide enough to encompass and deconvolve all possible foreground sources of emission.

The main scientific result of the mission will be an all-sky map of these fluctuations of the CBRF. In addition, the sky survey will be used to study in detail the sources of emission that contaminate the cosmological signal, and will result in a wealth of information on the dust and gas in both our own Galaxy and extragalactic sources. One specific notable result will be the measurement of the Sunyaev-Zeldovich effect (interactions of CMB photons with hot, intra-cluster gas) in many thousands of galaxy clusters, leading for example to the determination of cluster bulk velocities over scales of ~300 Mpc out to a redshift of ~1 with a velocity uncertainty of ~50 km/s.