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Title: The Atacama Cosmology Telescope: two-season ACTPol spectra and parameters

Abstract

We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time data collected during 2013–14 using two detector arrays at 149 GHz, from 548 deg{sup 2} of sky on the celestial equator. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008–10, in combination with planck and wmap data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the ΛCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters than the ACTPol temperature spectrum, including the baryon density, the acoustic peak angular scale, and the derived Hubble constant. The new ACTPol data provide information on damping tail parameters. The joint uncertainty on the number of neutrino species and the primordial helium fraction is reduced by 20% when adding ACTPol to Planck temperature data alone.

Authors:
 [1]; ; ;  [2];  [3]; ;  [4];  [5];  [6];  [7]; ;  [8];  [9];  [10]; ; ;  [11];  [12];  [13];
  1. UPMC Univ Paris 06, UMR7095, Institut d'Astrophysique de Paris, F-75014, Paris (France)
  2. Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States)
  3. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)
  4. Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States)
  5. Instituto de Astrofísica and Centro de Astro-Ingeniería, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago (Chile)
  6. Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States)
  7. School of Physics and Astronomy, Cardiff University, The Parade, Cardiff, Wales, CF24 3AA (United Kingdom)
  8. Sub-Department of Astrophysics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom)
  9. Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z4 (Canada)
  10. Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States)
  11. NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States)
  12. Department of Physics, Cornell University, Ithaca, NY 14853 (United States)
  13. Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON, M5S 3H8 (Canada)
Publication Date:
OSTI Identifier:
22676155
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 06; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BARYONS; CORRELATIONS; COSMOLOGY; DENSITY; EQUATOR; GHZ RANGE; HELIUM; NEUTRINOS; POLARIMETERS; POLARIZATION; SPECTRA; TELESCOPES

Citation Formats

Louis, Thibaut, Grace, Emily, Aiola, Simone, Choi, Steve K., Hasselfield, Matthew, Lungu, Marius, Angile, Elio, Maurin, Loïc, Addison, Graeme E., Ade, Peter A. R., Allison, Rupert, Calabrese, Erminia, Amiri, Mandana, Battaglia, Nicholas, Beall, James A., Britton, Joe, Cho, Hsiao-mei, De Bernardis, Francesco, Bond, J Richard, E-mail: louis@iap.fr, and and others. The Atacama Cosmology Telescope: two-season ACTPol spectra and parameters. United States: N. p., 2017. Web. doi:10.1088/1475-7516/2017/06/031.
Louis, Thibaut, Grace, Emily, Aiola, Simone, Choi, Steve K., Hasselfield, Matthew, Lungu, Marius, Angile, Elio, Maurin, Loïc, Addison, Graeme E., Ade, Peter A. R., Allison, Rupert, Calabrese, Erminia, Amiri, Mandana, Battaglia, Nicholas, Beall, James A., Britton, Joe, Cho, Hsiao-mei, De Bernardis, Francesco, Bond, J Richard, E-mail: louis@iap.fr, & and others. The Atacama Cosmology Telescope: two-season ACTPol spectra and parameters. United States. doi:10.1088/1475-7516/2017/06/031.
Louis, Thibaut, Grace, Emily, Aiola, Simone, Choi, Steve K., Hasselfield, Matthew, Lungu, Marius, Angile, Elio, Maurin, Loïc, Addison, Graeme E., Ade, Peter A. R., Allison, Rupert, Calabrese, Erminia, Amiri, Mandana, Battaglia, Nicholas, Beall, James A., Britton, Joe, Cho, Hsiao-mei, De Bernardis, Francesco, Bond, J Richard, E-mail: louis@iap.fr, and and others. Thu . "The Atacama Cosmology Telescope: two-season ACTPol spectra and parameters". United States. doi:10.1088/1475-7516/2017/06/031.
@article{osti_22676155,
title = {The Atacama Cosmology Telescope: two-season ACTPol spectra and parameters},
author = {Louis, Thibaut and Grace, Emily and Aiola, Simone and Choi, Steve K. and Hasselfield, Matthew and Lungu, Marius and Angile, Elio and Maurin, Loïc and Addison, Graeme E. and Ade, Peter A. R. and Allison, Rupert and Calabrese, Erminia and Amiri, Mandana and Battaglia, Nicholas and Beall, James A. and Britton, Joe and Cho, Hsiao-mei and De Bernardis, Francesco and Bond, J Richard, E-mail: louis@iap.fr and and others},
abstractNote = {We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time data collected during 2013–14 using two detector arrays at 149 GHz, from 548 deg{sup 2} of sky on the celestial equator. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008–10, in combination with planck and wmap data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the ΛCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters than the ACTPol temperature spectrum, including the baryon density, the acoustic peak angular scale, and the derived Hubble constant. The new ACTPol data provide information on damping tail parameters. The joint uncertainty on the number of neutrino species and the primordial helium fraction is reduced by 20% when adding ACTPol to Planck temperature data alone.},
doi = {10.1088/1475-7516/2017/06/031},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 06,
volume = 2017,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}
  • We 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{sup 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 atmore » 148 GHz comes from primary CMB after masking bright radio sources. The power from thermal and kinetic SZ is estimated to be B{sub 3000} = 6.8 {+-} 2.9 {mu}K{sup 2}, where B{sub l}{identical_to}l(l + 1)C{sub l}/2{pi}. The IR Poisson power at 148 GHz is B{sub 3000} = 7.8 {+-} 0.7 {mu}K{sup 2} (C{sub l} = 5.5 {+-} 0.5 nK{sup 2}), and a clustered IR component is required with B{sub 3000} = 4.6 {+-} 0.9 {mu}K{sup 2}, assuming an analytic model for its power spectrum shape. At 218 GHz only about 15% of the power, approximately 27 {mu}K{sup 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}){proportional_to}{nu}{sup {alpha}}. We estimate primary cosmological parameters from the less contaminated 148 GHz spectrum, marginalizing over SZ and source power. The {Lambda}CDM cosmological model is a good fit to the data ({chi}{sup 2}/dof = 29/46), and {Lambda}CDM 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 dn{sub s} /dln 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{mu} < 1.6 x 10{sup -7} (95% CL).« less
  • We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz and 218 GHz made by the Atacama Cosmology Telescope (ACT) in three seasons of observations from 2008 to 2010. A model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal Sunyaev-Zeldovich (tSZ) effect and the kinematic Sunyaev-Zeldovich (kSZ) effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources, and the correlation between the tSZ effect and infrared sources. The power ℓ{sup 2}C{sub ℓ}/2π of the thermal SZmore » power spectrum at 148 GHz is measured to be 3.4±1.4  μK{sup 2} at ℓ = 3000, while the corresponding amplitude of the kinematic SZ power spectrum has a 95% confidence level upper limit of 8.6  μK{sup 2}. Combining ACT power spectra with the WMAP 7-year temperature and polarization power spectra, we find excellent consistency with the LCDM model. We constrain the number of effective relativistic degrees of freedom in the early universe to be N{sub eff} = 2.79±0.56, in agreement with the canonical value of N{sub eff} = 3.046 for three massless neutrinos. We constrain the sum of the neutrino masses to be Σm{sub ν} < 0.39 eV at 95% confidence when combining ACT and WMAP 7-year data with BAO and Hubble constant measurements. We constrain the amount of primordial helium to be Y{sub p} = 0.225±0.034, and measure no variation in the fine structure constant α since recombination, with α/α{sub 0} = 1.004±0.005. We also find no evidence for any running of the scalar spectral index, dn{sub s}/dln k = −0.004±0.012.« less
  • We present constraints on cosmological parameters based on a sample of Sunyaev-Zeldovich-selected galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of 9 optically-confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 square degrees of sky surveyed during 2008 at 148GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a 4-parameter fit. Marginalizing over the values of themore » parameters in this fit with conservative priors gives {sigma}{sub 8} = 0.851 {+-} 0.115 and w = -1.14 {+-} 0.35 for a spatially-flat wCDM cosmological model with WMAP 7-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP 7-year constraints alone. Fixing the scaling relation between cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find {sigma}{sub 8} = 0.821 {+-} 0.044 and w = -1.05 {+-} 0.20. These results are consistent with constraints from WMAP 7 plus baryon acoustic oscillations plus type Ia supernoava which give {sigma}{sub 8} = 0.802 {+-} 0.038 and w = -0.98 {+-} 0.053. A stacking analysis of the clusters in this sample compared to clusters simulated assuming the fiducial model also shows good agreement. These results suggest that, given the sample of clusters used here, both the astrophysics of massive clusters and the cosmological parameters derived from them are broadly consistent with current models.« less
  • We present constraints on cosmological parameters based on a sample of Sunyaev-Zel'dovich-selected (SZ-selected) galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of nine optically confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 deg{sup 2} of sky surveyed during 2008 at 148 GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a four-parameter fit. Marginalizing over themore » values of the parameters in this fit with conservative priors gives {sigma}{sub 8} = 0.851 {+-} 0.115 and w = -1.14 {+-} 0.35 for a spatially flat wCDM cosmological model with Wilkinson Microwave Anisotropy Probe (WMAP) seven-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP seven-year constraints alone. Fixing the scaling relation between the cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find {sigma}{sub 8} = 0.821 {+-} 0.044 and w = -1.05 {+-} 0.20. These results are consistent with constraints from WMAP7 plus baryon acoustic oscillations plus Type Ia supernova which give {sigma}{sub 8} = 0.802 {+-} 0.038 and w = -0.98 {+-} 0.053. A stacking analysis of the clusters in this sample compared to clusters simulated assuming the fiducial model also shows good agreement. These results suggest that, given the sample of clusters used here, both the astrophysics of massive clusters and the cosmological parameters derived from them are broadly consistent with current models.« less