Wilkinson Microwave Anisotropy Probe
Names | Explorer 80 MAP Microwave Anisotropy Probe MIDEX-2 WMAP |
---|---|
Mission type | Cosmic microwave background Astronomy |
Operator | NASA |
COSPAR ID | 2001-027A |
SATCAT no. | 26859 |
Website | http://map.gsfc.nasa.gov/ |
Mission duration | 27 months (planned) 9 years (achieved)[1] |
Spacecraft properties | |
Spacecraft | Explorer LXXX |
Spacecraft type | Wilkinson Microwave Anisotropy Probe |
Bus | WMAP |
Manufacturer | NRAO |
Launch mass | 840 kg (1,850 lb)[2] |
Dry mass | 763 kg (1,682 lb) |
Dimensions | 3.6 × 5.1 m (12 × 17 ft) |
Power | 419 watts |
Start of mission | |
Launch date | 30 June 2001, 19:46:46 UTC[3] |
Rocket | Delta II 7425-10 (Delta 246) |
Launch site | Cape Canaveral, SLC-17B |
Contractor | Boeing Launch Services |
Entered service | 1 October 2001 |
End of mission | |
Disposal | Graveyard orbit |
Deactivated | 20 October 2010[4] |
Last contact | 19 August 2010 |
Orbital parameters | |
Reference system | Sun-Earth L2 orbit |
Regime | Lissajous orbit |
Main telescope | |
Type | Gregorian |
Diameter | 1.4 × 1.6 m (4 ft 7 in × 5 ft 3 in) |
Wavelengths | 23 GHz to 94 GHz |
Instruments | |
Pseudo-Correlation Radiometer | |
Wilkinson Microwave Anisotropy Probe mission patch Explorer program |
The Wilkinson Microwave Anisotropy Probe (WMAP), originally known as the Microwave Anisotropy Probe (MAP and Explorer 80), was a
WMAP's measurements played a key role in establishing the current Standard Model of Cosmology: the
−0.87% cold dark matter (CDM) that neither emits nor absorbs light; and 71.35%+0.95%
−0.96% of dark energy in the form of a cosmological constant that accelerates the expansion of the universe.[9] Less than 1% of the current content of the universe is in neutrinos, but WMAP's measurements have found, for the first time in 2008, that the data prefer the existence of a cosmic neutrino background[10] with an effective number of neutrino species of 3.26±0.35. The contents point to a Euclidean flat geometry
−0.0038. The WMAP measurements also support the cosmic inflation paradigm in several ways, including the flatness measurement.
The mission has won various awards: according to Science magazine, the WMAP was the
In October 2010, the WMAP spacecraft was derelict in a heliocentric graveyard orbit after completing nine years of operations.[14] All WMAP data are released to the public and have been subject to careful scrutiny. The final official data release was the nine-year release in 2012.[15][16]
Some aspects of the data are statistically unusual for the Standard Model of Cosmology. For example, the largest angular-scale measurement, the
Objectives
The WMAP objective was to measure the temperature differences in the
Development
The MAP mission was proposed to NASA in 1995, selected for definition study in 1996, and approved for development in 1997.[20][21]
The WMAP was preceded by two missions to observe the CMB; (i) the Soviet RELIKT-1 that reported the upper-limit measurements of CMB anisotropies, and (ii) the U.S. COBE satellite that first reported large-scale CMB fluctuations. The WMAP was 45 times more sensitive, with 33 times the angular resolution of its COBE satellite predecessor.[22] The successor European Planck mission (operational 2009–2013) had a higher resolution and higher sensitivity than WMAP and observed in 9 frequency bands rather than WMAP's 5, allowing improved astrophysical foreground models.
Spacecraft
The telescope's primary reflecting mirrors are a pair of
The receivers are polarization-sensitive differential radiometers measuring the difference between two telescope beams. The signal is amplified with High-electron-mobility transistor (HEMT) low-noise amplifiers, built by the National Radio Astronomy Observatory (NRAO). There are 20 feeds, 10 in each direction, from which a radiometer collects a signal; the measure is the difference in the sky signal from opposite directions. The directional separation azimuth is 180°; the total angle is 141°. To improve subtraction of foreground signals from our Milky Way galaxy, the WMAP used five discrete radio frequency bands, from 23 GHz to 94 GHz.[18]
Property | K-band | Ka-band | Q-band | V-band | W-band |
---|---|---|---|---|---|
Central wavelength (mm) | 13 | 9.1 | 7.3 | 4.9 | 3.2 |
Central GHz ) |
23 | 33 | 41 | 61 | 94 |
Bandwidth (GHz) | 5.5 | 7.0 | 8.3 | 14.0 | 20.5 |
Beam size (arcminutes) | 52.8 | 39.6 | 30.6 | 21 | 13.2 |
Number of radiometers | 2 | 2 | 4 | 4 | 8 |
System temperature (K) | 29 | 39 | 59 | 92 | 145 |
Sensitivity (mK s) | 0.8 | 0.8 | 1.0 | 1.2 | 1.6 |
The WMAP's base is a 5.0 m (16.4 ft)-diameter solar panel array that keeps the instruments in shadow during CMB observations, (by keeping the craft constantly angled at 22°, relative to the Sun). Upon the array sit a bottom deck (supporting the warm components) and a top deck. The telescope's cold components: the focal-plane array and the mirrors, are separated from the warm components with a cylindrical, 33 cm (13 in)-long thermal isolation shell atop the deck.[18]
Passive thermal radiators cool the WMAP to approximately 90 K (−183.2 °C; −297.7 °F); they are connected to the
The WMAP's calibration is effected with the CMB dipole and measurements of
Launch, trajectory, and orbit
The WMAP spacecraft arrived at the
Locating the spacecraft at Lagrange 2, (1,500,000 km (930,000 mi) from Earth) thermally stabilizes it and minimizes the contaminating solar, terrestrial, and lunar emissions registered. To view the entire sky, without looking to the Sun, the WMAP traces a path around L2 in a Lissajous orbit ca. 1.0° to 10°,[18] with a 6-month period.[20] The telescope rotates once every 2 minutes 9 seconds (0.464 rpm) and precesses at the rate of 1 revolution per hour.[18] WMAP measured the entire sky every six months, and completed its first, full-sky observation in April 2002.[21]
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WMAP launches from Kennedy Space Center, 30 June 2001
-
The WMAP's trajectory and orbit
-
WMAP's orbit and sky scan strategy
Experiment
Pseudo-Correlation Radiometer
The WMAP instrument consists of pseudo-correlation differential radiometers fed by two back-to-back 1.5 m (4 ft 11 in) primary Gregorian reflectors. This instrument uses five frequency bands from 22 GHz to 90 GHz to facilitate rejection of foreground signals from our own Galaxy. The WMAP instrument has a 3.5° x 3.5° field of view (FoV).[23]
Foreground radiation subtraction
The WMAP observed in five frequencies, permitting the measurement and subtraction of foreground contamination (from the Milky Way and extra-galactic sources) of the CMB. The main emission mechanisms are
Foreground contamination is removed in several ways. First, subtract extant emission maps from the WMAP's measurements; second, use the components' known spectral values to identify them; third, simultaneously fit the position and spectra data of the foreground emission, using extra data sets. Foreground contamination was reduced by using only the full-sky map portions with the least foreground contamination, while masking the remaining map portions.[18]
23 GHz | 33 GHz | 41 GHz | 61 GHz | 94 GHz |
Measurements and discoveries
One-year data release
On 11 February 2003, NASA published the first-year's worth of WMAP data. The latest calculated age and composition of the early universe were presented. In addition, an image of the early universe, that "contains such stunning detail, that it may be one of the most important scientific results of recent years" was presented. The newly released data surpass previous CMB measurements.[7]
Based upon the
Parameter | Symbol | Best fit (WMAP only) | Best fit (WMAP, extra parameter) | Best fit (all data) |
---|---|---|---|---|
Ga ) |
13.4±0.3 | – | 13.7±0.2 | |
Hubble's constant ( km⁄Mpc ·s ) |
72±5 | 70±5 | 71+4 −3 | |
Baryonic content | 0.024±0.001 | 0.023±0.002 | 0.0224±0.0009 | |
Matter content | 0.14±0.02 | 0.14±0.02 | 0.135+0.008 −0.009 | |
Optical depth to reionization | 0.166+0.076 −0.071 |
0.20±0.07 | 0.17±0.06 | |
Amplitude | A | 0.9±0.1 | 0.92±0.12 | 0.83+0.09 −0.08 |
Scalar spectral index | 0.99±0.04 | 0.93±0.07 | 0.93±0.03 | |
Running of spectral index | — | −0.047±0.04 | −0.031+0.016 −0.017 | |
Fluctuation amplitude at 8h−1 Mpc | 0.9±0.1 | — | 0.84±0.04 | |
Total density of the universe |
– | – | 1.02±0.02 |
Using the best-fit data and theoretical models, the WMAP team determined the times of important universal events, including the redshift of
−2 kyr. They determined the current density of baryons, (2.5±0.1)×10−7 cm−1, and the ratio of baryons to photons, 6.1+0.3
−0.2×10−10. The WMAP's detection of an early reionization excluded warm dark matter.[24]
The team also examined Milky Way emissions at the WMAP frequencies, producing a 208-point source catalogue.
Three-year data release
The three-year WMAP data were released on 17 March 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.
The 3-year WMAP data alone shows that the universe must have dark matter. Results were computed both only using WMAP data, and also with a mix of parameter constraints from other instruments, including other CMB experiments (Arcminute Cosmology Bolometer Array Receiver (ACBAR), Cosmic Background Imager (CBI) and BOOMERANG), Sloan Digital Sky Survey (SDSS), the 2dF Galaxy Redshift Survey, the Supernova Legacy Survey and constraints on the Hubble constant from the Hubble Space Telescope.[25]
Parameter | Symbol | Best fit (WMAP only) |
---|---|---|
Ga ) |
13.73+0.16 −0.15 | |
Hubble's constant ( km⁄Mpc·s ) |
73.2+3.1 −3.2 | |
Baryonic content | 0.0229±0.00073 | |
Matter content | 0.1277+0.0080 −0.0079 | |
Optical depth to reionization [a] | 0.089±0.030 | |
Scalar spectral index | 0.958±0.016 | |
Fluctuation amplitude at 8h−1 Mpc | 0.761+0.049 −0.048 | |
Tensor-to-scalar ratio [b] | r | <0.65 |
[a] ^ Optical depth to reionization improved due to polarization measurements.[26]
[b] ^ <0.30 when combined with SDSS data. No indication of non-gaussianity.[25]
Five-year data release
The five-year WMAP data were released on 28 February 2008. The data included new evidence for the
The improvement in the results came from both having an extra two years of measurements (the data set runs between midnight on 10 August 2001 to midnight of 9 August 2006), as well as using improved data processing techniques and a better characterization of the instrument, most notably of the beam shapes. They also make use of the 33-GHz observations for estimating cosmological parameters; previously only the 41-GHz and 61-GHz channels had been used.
Improved masks were used to remove foregrounds.[10] Improvements to the spectra were in the 3rd acoustic peak, and the polarization spectra.[10]
The measurements put constraints on the content of the universe at the time that the CMB was emitted; at the time 10% of the universe was made up of neutrinos, 12% of atoms, 15% of photons and 63% dark matter. The contribution of dark energy at the time was negligible.[27] It also constrained the content of the present-day universe; 4.6% atoms, 23% dark matter and 72% dark energy.[10]
The WMAP five-year data was combined with measurements from Type Ia supernova (SNe) and Baryon acoustic oscillations (BAO).[10]
The elliptical shape of the WMAP skymap is the result of a Mollweide projection.[28]
Parameter | Symbol | Best fit (WMAP only) | Best fit (WMAP + SNe + BAO) |
---|---|---|---|
Age of the universe (Ga) | 13.69±0.13 | 13.72±0.12 | |
Hubble's constant ( km⁄Mpc·s ) |
71.9+2.6 −2.7 |
70.5±1.3 | |
Baryonic content | 0.02273±0.00062 | 0.02267+0.00058 −0.00059 | |
Cold dark matter content | 0.1099±0.0062 | 0.1131±0.0034 | |
Dark energy content | 0.742±0.030 | 0.726±0.015 | |
Optical depth to reionization | 0.087±0.017 | 0.084±0.016 | |
Scalar spectral index | 0.963+0.014 −0.015 |
0.960±0.013 | |
Running of spectral index | −0.037±0.028 | −0.028±0.020 | |
Fluctuation amplitude at 8h−1 Mpc | 0.796±0.036 | 0.812±0.026 | |
Total density of the universe | 1.099+0.100 −0.085 |
1.0050+0.0060 −0.0061 | |
Tensor-to-scalar ratio | r | <0.43 | <0.22 |
The data puts limits on the value of the tensor-to-scalar ratio, r <0.22 (95% certainty), which determines the level at which gravitational waves affect the polarization of the CMB, and also puts limits on the amount of primordial
−3.167 kyr) and the redshift of matter/radiation equality, 3253+89
−87.[10]
The
23 GHz | 33 GHz | 41 GHz | 61 GHz | 94 GHz |
Seven-year data release
The seven-year WMAP data were released on 26 January 2010. As part of this release, claims for inconsistencies with the standard model were investigated.[29] Most were shown not to be statistically significant, and likely due to a posteriori selection (where one sees a weird deviation, but fails to consider properly how hard one has been looking; a deviation with 1:1000 likelihood will typically be found if one tries one thousand times). For the deviations that do remain, there are no alternative cosmological ideas (for instance, there seem to be correlations with the ecliptic pole). It seems most likely these are due to other effects, with the report mentioning uncertainties in the precise beam shape and other possible small remaining instrumental and analysis issues.
The other confirmation of major significance is of the total amount of matter/energy in the universe in the form of dark energy – 72.8% (within 1.6%) as non 'particle' background, and dark matter – 22.7% (within 1.4%) of non baryonic (sub-atomic) 'particle' energy. This leaves matter, or
Parameter | Symbol | Best fit (WMAP only) | Best fit (WMAP + ) |
---|---|---|---|
Age of the universe (Ga) | 13.75±0.13 | 13.75±0.11 | |
Hubble's constant ( km⁄Mpc·s ) |
71.0±2.5 | 70.4+1.3 −1.4 | |
Baryon density | 0.0449±0.0028 | 0.0456±0.0016 | |
Physical baryon density | 0.02258+0.00057 −0.00056 |
0.02260±0.00053 | |
Dark matter density | 0.222±0.026 | 0.227±0.014 | |
Physical dark matter density | 0.1109±0.0056 | 0.1123±0.0035 | |
Dark energy density | 0.734±0.029 | 0.728+0.015 −0.016 | |
Fluctuation amplitude at 8h−1 Mpc | 0.801±0.030 | 0.809±0.024 | |
Scalar spectral index | 0.963±0.014 | 0.963±0.012 | |
Reionization optical depth | 0.088±0.015 | 0.087±0.014 | |
*Total density of the universe | 1.080+0.093 −0.071 |
1.0023+0.0056 −0.0054 | |
*Tensor-to-scalar ratio, k0 = 0.002 Mpc−1 | r | < 0.36 (95% CL) | < 0.24 (95% CL) |
*Running of spectral index, k0 = 0.002 Mpc−1 | −0.034±0.026 | −0.022±0.020 | |
Note: * = Parameters for extended models (parameters place limits on deviations from the Lambda-CDM model)[30] |
23-GHz | 33-GHz | 41-GHz | 61-GHz | 94-GHz |
Nine-year data release
On 29 December 2012, the nine-year WMAP data and related images were released. 13.772±0.059 billion-year-old temperature fluctuations and a temperature range of ± 200 microkelvins are shown in the image. In addition, the study found that 95% of the early universe is composed of dark matter and dark energy, the curvature of space is less than 0.4% of "flat" and the universe emerged from the cosmic Dark Ages "about 400 million years" after the Big Bang.[15][16][33]
Parameter | Symbol | Best fit (WMAP only) | Best fit (WMAP + eCMB + BAO + H0) |
---|---|---|---|
Age of the universe (Ga) | 13.74±0.11 | 13.772±0.059 | |
Hubble's constant ( km⁄Mpc·s ) |
70.0±2.2 | 69.32±0.80 | |
Baryon density | 0.0463±0.0024 | 0.04628±0.00093 | |
Physical baryon density | 0.02264±0.00050 | 0.02223±0.00033 | |
Cold dark matter density | 0.233±0.023 | 0.2402+0.0088 −0.0087 | |
Physical cold dark matter density | 0.1138±0.0045 | 0.1153±0.0019 | |
Dark energy density | 0.721±0.025 | 0.7135+0.0095 −0.0096 | |
Density fluctuations at 8h−1 Mpc | 0.821±0.023 | 0.820+0.013 −0.014 | |
Scalar spectral index | 0.972±0.013 | 0.9608±0.0080 | |
Reionization optical depth | 0.089±0.014 | 0.081±0.012 | |
Curvature | 1 | −0.037+0.044 −0.042 |
−0.0027+0.0039 −0.0038 |
Tensor-to-scalar ratio (k0 = 0.002 Mpc−1) | r | < 0.38 (95% CL) | < 0.13 (95% CL) |
Running scalar spectral index | −0.019±0.025 | −0.023±0.011 |
Main result
The main result of the mission is contained in the various oval maps of the CMB temperature differences. These oval images present the temperature distribution derived by the WMAP team from the observations by the telescope during the mission. Measured is the temperature obtained from a Planck's law interpretation of the microwave background. The oval map covers the whole sky. The results are a snapshot of the universe around 375,000 years after the Big Bang, which happened about 13.8 billion years ago. The microwave background is very homogeneous in temperature (the relative variations from the mean, which presently is still 2.7 kelvins, are only of the order of 5×10−5). The temperature variations corresponding to the local directions are presented through different colors (the "red" directions are hotter, the "blue" directions cooler than the average).[citation needed]
Follow-on missions and future measurements
The original timeline for WMAP gave it two years of observations; these were completed by September 2003. Mission extensions were granted in 2002, 2004, 2006, and 2008 giving the spacecraft a total of 9 observing years, which ended August 2010[20] and in October 2010 the spacecraft was moved to a heliocentric "graveyard" orbit.[14]
The
(SPTpol) and others.On 21 March 2013, the European-led research team behind the Planck spacecraft released the mission's all-sky map of the cosmic microwave background.
See also
- Explorers Program
- Illustris project
- List of cosmic microwave background experiments
- List of cosmological computation software
- S150 Galactic X-Ray Mapping
References
- ^ "WMAP News: Events Timeline".
- ^ Siddiqi, Asif (2018). Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016 (PDF) (second ed.). NASA History Program Office.
- ^ "WMAP News: Events Timeline". NASA. 27 December 2010. Retrieved 8 July 2015.
- ^ NASA.gov This article incorporates text from this source, which is in the public domain.
- ^ "Wilkinson Microwave Anisotropy Probe: Overview". Goddard Space Flight Center. 4 August 2009. Retrieved 24 September 2009.
The WMAP (Wilkinson Microwave Anisotropy Probe) mission is designed to determine the geometry, content, and evolution of the universe via a 13 arcminutes FWHM resolution full sky map of the temperature anisotropy of the cosmic microwave background radiation.
This article incorporates text from this source, which is in the public domain. - ^ "Tests of Big Bang: The CMB". Goddard Space Flight Center. July 2009. Retrieved 24 September 2009.
Only with very sensitive instruments, such as COBE and WMAP, can cosmologists detect fluctuations in the cosmic microwave background temperature. By studying these fluctuations, cosmologists can learn about the origin of galaxies and large-scale structures of galaxies, and they can measure the basic parameters of the Big Bang theory.
This article incorporates text from this source, which is in the public domain. - ^ a b c "New image of infant universe reveals era of first stars, age of cosmos, and more". NASA / WMAP team. 11 February 2003. Archived from the original on 27 February 2008. Retrieved 27 April 2008.
- ISBN 978-0553593372.
- ^ Beringer, J.; et al. (Particle Data Group) (2013). "Astrophysics and Cosmology". Review of Particle Physics. This article incorporates text from this source, which is in the public domain.
- ^ a b c d e f g h i Hinshaw et al. (2009)
- ^ Seife (2003)
- ^ ""Super Hot" Papers in Science". unafold. October 2005. Retrieved 2 December 2022.
- ^ "Announcement of the Shaw Laureates 2010". Archived from the original on 4 June 2010.
- ^ a b "Mission Complete! WMAP Fires Its Thrusters For The Last Time". Discovery News. 7 October 2010. Retrieved 3 September 2021.
- ^ a b Gannon, M. (21 December 2012). "New 'Baby Picture' of Universe Unveiled". Space.com. Retrieved 21 December 2012.
- ^ S2CID 119271232.
- S2CID 118150531.
- ^ a b c d e f g h i j k l m n Bennett et al. (2003a)
- ^ Bennett et al. (2003b)
- ^ a b c d e "WMAP News: Facts". NASA. 22 April 2008. Retrieved 27 April 2008. This article incorporates text from this source, which is in the public domain.
- ^ a b "WMAP News: Events". NASA. 17 April 2008. Retrieved 27 April 2008. This article incorporates text from this source, which is in the public domain.
- ^ a b c Limon et al. (2008)
- ^ "Experiment: Pseudo-Correlation Radiometer". NASA. 28 October 2021. Retrieved 3 December 2021. This article incorporates text from this source, which is in the public domain.
- ^ a b c Spergel et al. (2003)
- ^ a b c Spergel et al. (2007)
- ^ Hinshaw et al. (2007)
- ^ a b "WMAP reveals neutrinos, end of dark ages, first second of universe". NASA / WMAP team. 7 March 2008. Retrieved 27 April 2008. This article incorporates text from this source, which is in the public domain.
- ^ WMAP 1-year Paper Figures, Bennett, et al. This article incorporates text from this source, which is in the public domain.
- S2CID 53521938.
- ^ a b Table 8 on p. 39 of Jarosik, N.; et al. "Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Sky Maps, Systematic Errors, and Basic Results" (PDF). WMAP Collaboration. NASA. Retrieved 4 December 2010. (from NASA's WMAP Documents page) This article incorporates text from this source, which is in the public domain.
- S2CID 9350615.
- ^ Riess, Adam G.; et al. "A Redetermination of the Hubble Constant with the Hubble Space Telescope from a Differential Distance Ladder" (PDF). hubblesite.org. Retrieved 4 December 2010.
- ^ Hinshaw, et al., 2013
- ^ Clavin, Whitney; Harrington, J. D. (21 March 2013). "Planck Mission Brings Universe Into Sharp Focus". NASA. Retrieved 21 March 2013. This article incorporates text from this source, which is in the public domain.
- ^ "Mapping the Early Universe". The New York Times. 21 March 2013. Retrieved 23 March 2013.
- S2CID 119262962.
Primary sources
- Bennett, C.; et al. (2003). "The Microwave Anisotropy Probe (MAP) Mission". Astrophysical Journal. 583 (1): 1–23. S2CID 8530058.
- Bennett, C.; et al. (2003). "First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission". Astrophysical Journal Supplement. 148 (1): 97–117. S2CID 10612050.
- Hinshaw, G.; et al. (2007). "Three-Year Wilkinson Microwave Anisotropy Probe (WMAP1) Observations: Temperature Analysis". Astrophysical Journal Supplement. 170 (2): 288–334. S2CID 15554608.
- Hinshaw, G.; et al. (February 2009). "Five-Year Wilkinson Microwave Anisotropy Probe Observations: Data Processing, Sky Maps, and Basic Results". The Astrophysical Journal Supplement. 180 (2). WMAP Collaboration: 225–245. S2CID 3629998.
- "Wilkinson Microwave Anisotropy Probe (WMAP): Five–Year Explanatory Supplement" (PDF). 20 March 2008.
- S2CID 120116611.
- Spergel, D. N.; et al. (2003). "First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters". Astrophysical Journal Supplement. 148 (1): 175–194. S2CID 10794058.
- Sergel, D. N.; et al. (2007). "Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Implications for Cosmology". Astrophysical Journal Supplement. 170 (2): 377–408. S2CID 1386346.
- Komatsu; Dunkley; Nolta; Bennett; Gold; Hinshaw; Jarosik; Larson; et al. (2009). "Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation". The Astrophysical Journal Supplement Series. 180 (2): 330–376. S2CID 119290314.
Further reading
- .
External links
- Sizing up the universe
- Big Bang glow hints at funnel-shaped Universe, New Scientist, 15 April 2004
- NASA 16 March 2006 WMAP inflation related press release Archived 22 November 2013 at the Wayback Machine
- Seife, Charles (2003). "With Its Ingredients MAPped, Universe's Recipe Beckons". Science. 300 (5620): 730–731. S2CID 585072.
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