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The Atacama Cosmology Telescope: Cosmological Parameters from the 2008 Power SpectrumWe present cosmological parameters derived from the angular power spectrum of the cosmic microwave background (CMB) radiation observed at 148 GHz and 218 GHz over 296 deg(exp 2) with the Atacama Cosmology Telescope (ACT) during its 2008 season. ACT measures fluctuations at scales 500 < l < 10,000. We fit a model for the lensed CMB, Sunyaev-Zel'dovich (SZ), and foreground contribution to the 148 GHz and 218 GHz power spectra, including thermal and kinetic SZ, Poisson power from radio and infrared point sources, and clustered power from infrared point sources. At l = 3000, about half the power at 148 GHz comes from primary CMB after masking bright radio sources. The power from thermal and kinetic SZ is estimated to be Beta(sub 3000) is identical to 6.8 +/- 2.9 mu K (exp 2), where Beta (sub l) is identical to l(l + 1) C(sub l)/2pi. The IR Poisson power at 148 GHz is Bewta(sub 3000) 7.8 +/- 0.7 muK(exp 2) (C(sub l) = 5.5 +/- 0.5 nK(exp 2)), and a clustered IR component is required with Beta (sub 3000) = 4.6 +/- 0.9 muK(exp 2), assuming an analytic model for its power spectrum shape. At 218 GHz only about 15% of the power, approximately 27 mu K(exp 2), is CMB anisotropy at l = 3000. The remaining 85% is attributed to IR sources (approximately 50% Poisson and 35% clustered), with spectral index alpha = 3.69 +/- 0.14 for flux scaling as S(nu) varies as nu(sup alpha). We estimate primary cosmological parameters from the less contaminated 148 GHz spectrum, marginalizing over SZ and source power. The ACDM cosmological model is a good fit to the data (chi square/dof = 29/46), and ACDM parameters estimated from ACT+Wilkinson Microwave Anisotropy Probe (WMAP) are consistent with the seven-year WMAP limits, with scale invariant n(sub s) = 1 excluded at 99.7% confidence level (CL) (3 sigma). A model with no CMB lensing is disfavored at 2.8 sigma. By measuring the third to seventh acoustic peaks, and probing the Silk damping regime, the ACT data improve limits on cosmological parameters that affect the small-scale CMB power. The ACT data combined with WMAP give a 6 sigma detection of primordial helium, with Y(sub p) = 0.313 +/- 0.044, and a 4 sigma detection of relativistic species, assumed to be neutrinos, with N(sub eff) = 5.3 +/- 1.3 (4.6 +/- 0.8 with BAO+H(sub 0) data). From the CMB alone the running of the spectral index is constrained to be d(sub s) / d ln k = -0,034 +/- 0,018, the limit on the tensor-to-scalar ratio is r < 0,25 (95% CL), and the possible contribution of Nambu cosmic strings to the power spectrum is constrained to string tension G(sub mu) < 1.6 x 10(exp -7) (95% CL),
Document ID
20120002547
Document Type
Reprint (Version printed in journal)
Authors
Dunkley, J. (Princeton Univ. Princeton, NJ, United States)
Hlozek, R. (Oxford Univ. Oxford, United Kingdom)
Sievers, J. (Toronto Univ. Ontario, Canada)
Acquaviva, V. (Princeton Univ. Princeton, NJ, United States)
Ade, P. A. R. (Cardiff Univ. United Kingdom)
Aguirre, P. (Pontificia Univ. Catolica de Chile Santiago, Chile)
Amiri, M. (British Columbia Univ. Vancouver, British Columbia, Canada)
Appel, J. W. (Princeton Univ. Princeton, NJ, United States)
Barrientos, L. F. (Pontificia Univ. Catolica de Chile Santiago, Chile)
Battistelli, E. S. (British Columbia Univ. Vancouver, British Columbia, Canada)
Bond, J. R. (Toronto Univ. Ontario, Canada)
Brown, B. (Pittsburgh Univ. Pittsburgh, PA, United States)
Burger, B. (British Columbia Univ. Vancouver, British Columbia, Canada)
Chervenak, J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Das, S. (Princeton Univ. Princeton, NJ, United States)
Devlin, M. J. (Philadelphia Univ. Philadelphia, PA, United States)
Dicker, S. R. (Philadelphia Univ. Philadelphia, PA, United States)
Bertrand Doriese, W. (Quantum Devices, Inc. Boulder, CO, United States)
Dunner, R. (Pontificia Univ. Catolica de Chile Santiago, Chile)
Essinger-Hileman, T. (Princeton Univ. Princeton, NJ, United States)
Fisher, R. P. (Princeton Univ. Princeton, NJ, United States)
Fowler, J. W. (Princeton Univ. Princeton, NJ, United States)
Hajian, A. (Princeton Univ. Princeton, NJ, United States)
Moseley, H. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Wollack, E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 25, 2013
Publication Date
September 6, 2011
Publication Information
Publication: The Astrophysical Journal
Volume: 739
Issue: 1
Subject Category
Astrophysics
Report/Patent Number
GSFC.JA.5605.2011
Funding Number(s)
CONTRACT_GRANT: NSF AST-0546035
CONTRACT_GRANT: AST-0707731
CONTRACT_GRANT: NSF AST-0408698
CONTRACT_GRANT: PIRE-0507768
CONTRACT_GRANT: NNX08AH30G
CONTRACT_GRANT: DE-AC3-76SF00515
CONTRACT_GRANT: PHY-0355328
Distribution Limits
Public
Copyright
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