WILKINSON MICROWAVE ANISOTROPY PROBE

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The 'Wilkinson Microwave Anisotropy Probe' ('WMAP') is a NASA satellite mission led by Professor Charles L. Bennett of Johns Hopkins University, whose mission is to survey the sky to measure the temperature of the radiant heat left over from the Big Bang. The satellite was launched by a Delta II rocket on June 30, 2001, at 3:46 p.m. EDT from Cape Canaveral Air Force Station, Florida, USA.
WMAP was the Breakthrough of the Year for 2003 according to Science magazine.[1] Mission results papers were #1 and #2 on the list of "Super Hot Papers in Science Since 2003."[2]
The goal of WMAP is to map out minute temperature differences in the Cosmic Microwave Background (CMB) radiation in order to help test theories of the nature of the universe. It is the successor to COBE and one of the series of medium-class explorer (MIDEX) satellites.
WMAP is named after Dr. David Wilkinson, a member of the science team and pioneer in the study of cosmic background radiation. The science goals of the WMAP broadly dictate that the relative CMB temperature be measured accurately over the full sky with high angular resolution and sensitivity. The overriding priority in the design was the need to control systematic errors in the final maps. The specific goal of WMAP is to map the relative CMB temperature over the full sky with an angular resolution of at least 0.3°, a sensitivity of 20 µK per 0.3° square pixel, with systematic artifacts limited to 5 µK per pixel.
To achieve these goals, WMAP uses differential microwave radiometers that measure temperature differences between two points on the sky. WMAP observes the sky from an orbit about the L2 Sun-Earth Lagrangian point, 1.5 million km from Earth.

This vantage point offers an exceptionally stable environment for observing, since the observatory can always point away from the Sun, Earth and Moon while maintaining an unobstructed view to deep space. WMAP scans the sky in such a way as to cover ~30% of the sky each day and as the L2 point follows the Earth around the Sun WMAP observes the full sky every six months. To facilitate rejection of foreground signals from our own Galaxy, WMAP uses five separate frequency bands from 22 to 90 GHz.
On February 11, 2003, NASA issued a press release regarding the age and composition of the universe. This release included the "best baby picture" of the universe taken up to that point. According to NASA, this picture "contains such stunning detail that it may be one of the most important scientific results of recent years". The new data were found to be in agreement with previous CMB measurements and with the most popular Lambda-CDM models.
The three-year WMAP data were released at noon on March 17, 2006. The data included temperature and polarization measurements of the CMB, which provided further confirmation of the standard flat Lambda-CDM model and new evidence in support of inflation.

Contents

Findings so far from WMAP

Other Instruments for measuring fluctuations in the Cosmic Microwave Background

Earlier

Later

Past and Current WMAP Science Team Members

References

See also

Findings so far from WMAP

WMAP provided higher accuracy measurements of many cosmological parameters than had been available from previous instruments. According to current models of the universe, WMAP data show:

★ The universe is 13.7 ± 0.2 billion years old [3].^[1]

★ The universe is composed of:

★
★ 4% ordinary baryonic matter

★
★ 22% an unknown type of dark matter, which does not emit or absorb light.

★
★ 74% a mysterious dark energy, which acts to accelerate expansion.

★ The cosmological scenarios of cosmic inflation are in better agreement with the three-year data, although there is still an unexplained anomaly on the largest angular measurement of the quadrupole moment.

★ The Hubble constant is 70 (km/s)/Mpc, +2.4/-3.2

★ The data are consistent with a flat geometry, with Ω = 1.02 +/- 0.02.

★ CMB polarization results provide experimental confirmation of cosmic inflation favoring the simplest versions of the theory.

Other Instruments for measuring fluctuations in the Cosmic Microwave Background

Main articles: Cosmic microwave background experiments

Earlier

Before WMAP, there were several incremental improvements in our maps of the Cosmic Microwave Background:

★ COBE - measured the very large scale fluctuations

★ Cosmic Anisotropy Telescope - measured the very small scale fluctuations in small regions of the sky

★ Boomerang - measured fluctuations with improved precision

★ Maxima - measured fluctuations with improved precision

★ Cosmic Background Imager - measured the very small scale fluctuations with improved precision in small regions of the sky

★ Very Small Array - measured fluctuations with improved precision in small regions of the sky

Later

Future instruments are expected to build upon WMAP's results. These include:

★ Clover - improved precision and B-mode polarization measurements

★ Planck Surveyor - improved precision at all angular scales over the whole sky

Past and Current WMAP Science Team Members

Past and Current WMAP Science Team are:

'Member, Institution'

Charles L. Bennett (PI) , Johns Hopkins University

Mark Halpern , University of British Columbia

Gary Hinshaw , NASA Goddard Space Flight Center

Norman Jarosik , Princeton University

Al Kogut , NASA Goddard Space Flight Center

Michele Limon , NASA Goddard Space Flight Center/SSAI

Stephan Meyer , University of Chicago

Lyman Page , Princeton University

David Spergel , Princeton University

Greg Tucker , Brown University

David Wilkinson , Princeton University

Ed Wollack , NASA Goddard Space Flight Center

Ned Wright , University of California- Los Angeles

Rachel Bean , Cornell University

Olivier Dore , University of Toronto

Michael Nolta , University of Toronto

Eiichiro Komatsu , Univ. of Texas, Austin

Hiranya Peiris, University of Chicago

Licia Verde , Univ. of Pennsylvania

Chris Barnes , Princeton University

Michael Greason , NASA Goddard Space Flight Center

Robert Hill , NASA Goddard Space Flight Center

Alan Kogut , NASA Goddard Space Flight Center

Michele Limon, NASA Goddard Space Flight Center

Nils Odegard , NASA Goddard Space Flight Center

Janet Weiland , NASA Goddard Space Flight Center

References

1. First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters, D. N. Spergel, L. Verde, H. V. Peiris, E. Komatsu, M. R. Nolta, C. L. Bennett, M. Halpern, G. Hinshaw, N. Jarosik, A. Kogut, M. Limon, S. S. Meyer, L. Page, G. S. Tucker, J. L. Weiland, E. Wollack, E. L. Wright, , , Astrophys. J .Suppl., 2003


★ WMAP Website at NASA GSFC

★ NASA's February 11, 2003 press release

★ local cosmological parameters - WMAP (1st Year) team

★ Anisotropy

★ Seife, Charles, BREAKTHROUGH OF THE YEAR: Illuminating the Dark Universe, Science 2003 302: 2038–2039. The article includes a bibliography and interesting web links.

★ Sizing up the universe

★ About WMAP and the Cosmic Microwave Background - Article at Space.com

★ The 'Shape' of the Universe according to WMAP.

★ Cosmology blog comments on the three-year data.

★ NASA March 16, 2006 WMAP inflation related press release

★ With Its Ingredients MAPped, Universe's Recipe Beckons, , Charles, Seife, Science, 2003

See also

★ WMAP Cold Spot