wilkinson microwave anisotropy probe
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WMAP:. Wilkinson Microwave Anisotropy Probe. AST 403 Jimmy Jones. WMAP:. Cosmic Microwave Background Radiation (CMB). CMB. Big Bang predicts early universe was very hot – photons produced As universe expands, the gas within cools and photons lose energy - PowerPoint PPT PresentationTRANSCRIPT
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Wilkinson Microwave Wilkinson Microwave Anisotropy ProbeAnisotropy Probe
AST 403Jimmy Jones
WMAP:WMAP:
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WMAP:WMAP:
Cosmic Cosmic Microwave Microwave Background Background Radiation Radiation
(CMB)(CMB)
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CMBCMB• Big Bang predicts
early universe was very hot – photons produced
• As universe expands, the gas within cools and photons lose energy
• Implies universe should be filled with radiation left over from Big Bang - CMB
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CMB DiscoveryCMB Discovery
• Initially predicted by George Gamow in 1948 and by Ralph Alpher and Robert Herman in 1950
• Inadvertently observed by Arno Penzias and Robert Wilson in 1965
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COBECOBE• Cosmic Background
Explorer• Launched November
1989• Designed to measure
cosmic background radiation
• Possessed three instruments:– DIRBE – infrared– DMR – microwave– FIRAS – spectrum
analysis
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COBE DataCOBE Data
• COBE helped to determine average temperature of CMB as 2.725 kelvins
• This temperature is very uniform
• However, COBE was able to detect slight variations
Red areas .0002 degrees Red areas .0002 degrees warmer than black areaswarmer than black areas
Milky WayMilky Way
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Why Study CMBs?Why Study CMBs?• CMBs provide
information on the universe as early as 400,000 years after Big Bang
• (as opposed to studying visible light sources in the million year range)
• Studying fluctuations can provide insight into origin of galaxies and measure the basic parameters of the Big Bang theory.
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How?How?
• The Big Bang can account for background radiation and the formation of light elements but not galaxies
• One theory is:– Large objects potentially grew out of small
fluctuations in the background radiation– Areas of greater density expand slower
allowing for build up of even greater densities
– Further study of these anomalies can help to prove the validity of this theory
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WMAPWMAP
Microwave Microwave Anisotropy Probe:Anisotropy Probe:
The MissionThe Mission
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Satellite TimelineSatellite Timeline
• Launched June 30, 2001
• Completed prime 2 years of mission operations September 2003
• Extensions granted to September 2009
• Orbits in L2 with back to Sun and Earth
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Satellite ComponentsSatellite Components
• Uses differential microwave radiometers that measure temperature differences between two points on the sky.
• To facilitate rejection of foreground signals from our own Galaxy, WMAP uses five separate frequency bands from 22 to 90 GHz.
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Measurement Error Measurement Error ControlControl
• Sensitivity better than 20 microkelvins per 0.3 degree square pixel
• Measures temp. differences rather than absolute temp (implies most spurious signals will cancel)
• Spins and precesses like a top allowing an observing pattern that covers 30% of sky during each 1 hour precession.
• Five frequency bands (as compared to COBE’s three)
• The L2 Lagrange point offers exceptionally stable environment and unobstructed view of deep space.
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Data AcquisitionData Acquisition
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WMAPWMAP
DataData
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Universes’ ‘Baby Universes’ ‘Baby Picture’Picture’
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Universes’ FingerprintUniverses’ Fingerprint
• Universes’ baby picture provides unique ‘fingerprint’ that can be analyzed to determine characteristics of the universe, past and present
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Composition of Composition of UniverseUniverse
• Although the data is still be analyzed a wealth of information has already been discovered
• Based on analysis a composition of the primordial universe has been proposed
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How?How?
• WMAP measured temperature fluctuations in term of their ‘angular fluctuation spectrum’.
• Graphing this data produced features generated by the various physical processes that produce different amounts of energy (temperature) at the different angular scales.
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How IIHow II
Variations due to Variations due to gravity?gravity?
Dark Matter?Dark Matter?
Variations due to Variations due to sound waves? sound waves?
Atoms?Atoms?
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Shape of the UniverseShape of the Universe• The vertical peaks and
angular scale in the previous graph provide information to the density as well
• If the density is greater than the critical density a closed universe is produced
• If the density is less than the critical density an open universe is produced
• If the density is equal to the critical density a flat universe is produce
• Findings of the WMAP mission appear consistent with a flat universe geometry
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Rapid Inflation Rapid Inflation
• Measures of the fluctuations on the angular scale seem to support the theory that the universe underwent a period of extremely rapid (exponential) expansion
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More DataMore Data
• The universe is 13.7 billion ± 200 million years old
• The Hubble constant is 70 (km/sec)/Mpc, +2.4/-3.2
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ReferencesReferences
• General Information– http://map.gsfc.nasa.gov/m_mm.html– http://en.wikipedia.org/wiki/WMAP
• CMB– http://www.astro.ubc.ca/people/scott/faq_basic.html
Missions
• Results– http://www.cnn.com/2003/TECH/space/02/11/cosmic.p
ortrait/
• COBE– http://lambda.gsfc.nasa.gov/product/cobe/