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Title: SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS

Abstract

The WMAP mission has produced sky maps from seven years of observations at L2. We present the angular power spectra derived from the seven-year maps and discuss the cosmological conclusions that can be inferred from WMAP data alone. With the seven-year data, the temperature (TT) spectrum measurement has a signal-to-noise ratio per multipole that exceeds unity for l < 919; and in band powers of width {Delta}l = 10, the signal-to-noise ratio exceeds unity up to l = 1060. The third acoustic peak in the TT spectrum is now well measured by WMAP. In the context of a flat {Lambda}CDM model, this improvement allows us to place tighter constraints on the matter density from WMAP data alone, {Omega}{sub m} h {sup 2} = 0.1334{sup +0.0056}{sub -0.0055}, and on the epoch of matter-radiation equality, z{sub eq} = 3196{sup +134}{sub -133}. The temperature-polarization (TE) spectrum is detected in the seven-year data with a significance of 20{sigma}, compared to 13{sigma} with the five-year data. We now detect the second dip in the TE spectrum near l {approx} 450 with high confidence. The TB and EB spectra remain consistent with zero, thus demonstrating low systematic errors and foreground residuals in the data. The low-lmore » EE spectrum, a measure of the optical depth due to reionization, is detected at 5.5{sigma} significance when averaged over l = 2-7: l(l + 1)C {sup EE}{sub l}/(2{pi}) = 0.074{sup +0.034}{sub -0.025} {mu}K{sup 2} (68% CL). We now detect the high-l, 24 {<=} l {<=} 800, EE spectrum at over 8{sigma}. The BB spectrum, an important probe of gravitational waves from inflation, remains consistent with zero; when averaged over l = 2-7, l(l + 1)C {sup BB}{sub l}/(2{pi}) < 0.055 {mu}K{sup 2} (95% CL). The upper limit on tensor modes from polarization data alone is a factor of two lower with the seven-year data than it was using the five-year data. The data remain consistent with the simple {Lambda}CDM model: the best-fit TT spectrum has an effective {chi}{sup 2} of 1227 for 1170 degrees of freedom, with a probability to exceed of 9.6%. The allowable volume in the six-dimensional space of {Lambda}CDM parameters has been reduced by a factor of 1.5 relative to the five-year volume, while the {Lambda}CDM model that allows for tensor modes and a running scalar spectral index has a factor of three lower volume when fit to the seven-year data. We test the parameter recovery process for bias and find that the scalar spectral index, n{sub s} , is biased high, but only by 0.09{sigma}, while the remaining parameters are biased by <0.15{sigma}. The improvement in the third peak measurement leads to tighter lower limits from WMAP on the number of relativistic degrees of freedom (e.g., neutrinos) in the early universe: N{sub eff}>2.7(95%CL). Also, using WMAP data alone, the primordial helium mass fraction is found to be Y{sub He} = 0.28{sup +0.14}{sub -0.15}, and with data from higher-resolution cosmic microwave background experiments included, we now establish the existence of pre-stellar helium at >3{sigma}. These new WMAP measurements provide important tests of big bang cosmology.« less

Authors:
; ;  [1];  [2]; ; ;  [3];  [4];  [5];  [6]; ; ;  [7]; ;  [8];  [9];  [10]; ;  [11];  [12]
  1. Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2686 (United States)
  2. Astrophysics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom)
  3. Code 665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  4. Department of Astronomy, University of Texas, Austin, 2511 Speedway, RLM 15.306, Austin, TX 78712 (United States)
  5. Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto, ON M5S 3H8 (Canada)
  6. Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada)
  7. ADNET Systems, Inc., 7515 Mission Dr., Suite A100 Lanham, MD 20706 (United States)
  8. Department of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544-0708 (United States)
  9. Columbia Astrophysics Laboratory, 550 W. 120th St., Mail Code 5247, New York, NY 10027-6902 (United States)
  10. Departments of Astrophysics and Physics, KICP and EFI, University of Chicago, Chicago, IL 60637 (United States)
  11. Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544-1001 (United States)
  12. Department of Physics, Brown University, 182 Hope St., Providence, RI 02912-1843 (United States)
Publication Date:
OSTI Identifier:
21560534
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 192; Journal Issue: 2; Other Information: DOI: 10.1088/0067-0049/192/2/16
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; COSMOLOGY; NONLUMINOUS MATTER; PROBES; RELICT RADIATION; SIGNAL-TO-NOISE RATIO; UNIVERSE; DIMENSIONLESS NUMBERS; ELECTROMAGNETIC RADIATION; MATTER; MICROWAVE RADIATION; RADIATIONS

Citation Formats

Larson, D., Bennett, C. L., Gold, B., Dunkley, J., Hinshaw, G., Kogut, A., Wollack, E., Komatsu, E., Nolta, M. R., Halpern, M., Hill, R. S., Odegard, N., Weiland, J. L., Jarosik, N., Page, L., Limon, M., Meyer, S. S., Smith, K. M., Spergel, D. N., and Tucker, G. S., E-mail: dlarson@pha.jhu.edu. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS. United States: N. p., 2011. Web. doi:10.1088/0067-0049/192/2/16.
Larson, D., Bennett, C. L., Gold, B., Dunkley, J., Hinshaw, G., Kogut, A., Wollack, E., Komatsu, E., Nolta, M. R., Halpern, M., Hill, R. S., Odegard, N., Weiland, J. L., Jarosik, N., Page, L., Limon, M., Meyer, S. S., Smith, K. M., Spergel, D. N., & Tucker, G. S., E-mail: dlarson@pha.jhu.edu. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS. United States. doi:10.1088/0067-0049/192/2/16.
Larson, D., Bennett, C. L., Gold, B., Dunkley, J., Hinshaw, G., Kogut, A., Wollack, E., Komatsu, E., Nolta, M. R., Halpern, M., Hill, R. S., Odegard, N., Weiland, J. L., Jarosik, N., Page, L., Limon, M., Meyer, S. S., Smith, K. M., Spergel, D. N., and Tucker, G. S., E-mail: dlarson@pha.jhu.edu. Tue . "SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS". United States. doi:10.1088/0067-0049/192/2/16.
@article{osti_21560534,
title = {SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS},
author = {Larson, D. and Bennett, C. L. and Gold, B. and Dunkley, J. and Hinshaw, G. and Kogut, A. and Wollack, E. and Komatsu, E. and Nolta, M. R. and Halpern, M. and Hill, R. S. and Odegard, N. and Weiland, J. L. and Jarosik, N. and Page, L. and Limon, M. and Meyer, S. S. and Smith, K. M. and Spergel, D. N. and Tucker, G. S., E-mail: dlarson@pha.jhu.edu},
abstractNote = {The WMAP mission has produced sky maps from seven years of observations at L2. We present the angular power spectra derived from the seven-year maps and discuss the cosmological conclusions that can be inferred from WMAP data alone. With the seven-year data, the temperature (TT) spectrum measurement has a signal-to-noise ratio per multipole that exceeds unity for l < 919; and in band powers of width {Delta}l = 10, the signal-to-noise ratio exceeds unity up to l = 1060. The third acoustic peak in the TT spectrum is now well measured by WMAP. In the context of a flat {Lambda}CDM model, this improvement allows us to place tighter constraints on the matter density from WMAP data alone, {Omega}{sub m} h {sup 2} = 0.1334{sup +0.0056}{sub -0.0055}, and on the epoch of matter-radiation equality, z{sub eq} = 3196{sup +134}{sub -133}. The temperature-polarization (TE) spectrum is detected in the seven-year data with a significance of 20{sigma}, compared to 13{sigma} with the five-year data. We now detect the second dip in the TE spectrum near l {approx} 450 with high confidence. The TB and EB spectra remain consistent with zero, thus demonstrating low systematic errors and foreground residuals in the data. The low-l EE spectrum, a measure of the optical depth due to reionization, is detected at 5.5{sigma} significance when averaged over l = 2-7: l(l + 1)C {sup EE}{sub l}/(2{pi}) = 0.074{sup +0.034}{sub -0.025} {mu}K{sup 2} (68% CL). We now detect the high-l, 24 {<=} l {<=} 800, EE spectrum at over 8{sigma}. The BB spectrum, an important probe of gravitational waves from inflation, remains consistent with zero; when averaged over l = 2-7, l(l + 1)C {sup BB}{sub l}/(2{pi}) < 0.055 {mu}K{sup 2} (95% CL). The upper limit on tensor modes from polarization data alone is a factor of two lower with the seven-year data than it was using the five-year data. The data remain consistent with the simple {Lambda}CDM model: the best-fit TT spectrum has an effective {chi}{sup 2} of 1227 for 1170 degrees of freedom, with a probability to exceed of 9.6%. The allowable volume in the six-dimensional space of {Lambda}CDM parameters has been reduced by a factor of 1.5 relative to the five-year volume, while the {Lambda}CDM model that allows for tensor modes and a running scalar spectral index has a factor of three lower volume when fit to the seven-year data. We test the parameter recovery process for bias and find that the scalar spectral index, n{sub s} , is biased high, but only by 0.09{sigma}, while the remaining parameters are biased by <0.15{sigma}. The improvement in the third peak measurement leads to tighter lower limits from WMAP on the number of relativistic degrees of freedom (e.g., neutrinos) in the early universe: N{sub eff}>2.7(95%CL). Also, using WMAP data alone, the primordial helium mass fraction is found to be Y{sub He} = 0.28{sup +0.14}{sub -0.15}, and with data from higher-resolution cosmic microwave background experiments included, we now establish the existence of pre-stellar helium at >3{sigma}. These new WMAP measurements provide important tests of big bang cosmology.},
doi = {10.1088/0067-0049/192/2/16},
journal = {Astrophysical Journal, Supplement Series},
number = 2,
volume = 192,
place = {United States},
year = {Tue Feb 01 00:00:00 EST 2011},
month = {Tue Feb 01 00:00:00 EST 2011}
}