Article

# A Measurement of the Damping Tail of the Cosmic Microwave Background Power Spectrum with the South Pole Telescope

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(Impact Factor: 6.28). 05/2011; 743(1). DOI: 10.1088/0004-637X/743/1/28
Source: arXiv

ABSTRACT We present a measurement of the angular power spectrum of the cosmic
microwave background (CMB) using data from the South Pole Telescope (SPT). The
data consist of 790 square degrees of sky observed at 150 GHz during 2008 and
2009. Here we present the power spectrum over the multipole range 650 < ell <
3000, where it is dominated by primary CMB anisotropy. We combine this power
spectrum with the power spectra from the seven-year Wilkinson Microwave
Anisotropy Probe (WMAP) data release to constrain cosmological models. We find
that the SPT and WMAP data are consistent with each other and, when combined,
are well fit by a spatially flat, LCDM cosmological model. The SPT+WMAP
constraint on the spectral index of scalar fluctuations is ns = 0.9663 +/-
0.0112. We detect, at ~5-sigma significance, the effect of gravitational
lensing on the CMB power spectrum, and find its amplitude to be consistent with
the LCDM cosmological model. We explore a number of extensions beyond the LCDM
model. Each extension is tested independently, although there are degeneracies
between some of the extension parameters. We constrain the tensor-to-scalar
ratio to be r < 0.21 (95% CL) and constrain the running of the scalar spectral
index to be dns/dlnk = -0.024 +/- 0.013. We strongly detect the effects of
primordial helium and neutrinos on the CMB; a model without helium is rejected
at 7.7-sigma, while a model without neutrinos is rejected at 7.5-sigma. The
primordial helium abundance is measured to be Yp = 0.296 +/- 0.030, and the
effective number of relativistic species is measured to be Neff = 3.85 +/-
0.62. The constraints on these models are strengthened when the CMB data are
combined with measurements of the Hubble constant and the baryon acoustic
oscillation feature. Notable improvements include ns = 0.9668 +/- 0.0093, r <
0.17 (95% CL), and Neff = 3.86 +/- 0.42. The SPT+WMAP data show...

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Available from: Antony A. Stark, Dec 22, 2014
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• "We use the BBN PArthENoPE code [96] [97] to compute the helium abundance, Y P , for different values of Ω b h 2 , ∆N ef f , ξ ν and changes of neutron and proton interaction rates due to We adapt the latest version of the publicly available package CosmoMC [81] for our cosmological analysis and use the following datasets and likelihood codes: • The Planck CMB anisotropy angular power spectrum, combined with WMAP-9 year polarization power spectrum at low ℓ [82] and the corresponding codes [1] [83]: Commander, that computes the low-l Planck likelihood, CamSpec, that computes the Planck likelihood for 50 ≤ l ≤ 2500, LowLike, that computes the likelihoods for 2 ≤ l ≤ 32 polarization data and Lensing, that computes the likelihoods from Planck lensing power spectrum for 40 ≤ l ≤ 400 [84]. • The high-l CMB data from Atacama Cosmology Telescope(ACT) [85] [86] and the South Pole Telescope (SPT) [87] [88]. "
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ABSTRACT: Few independent detections of a weak X-ray emission line at an energy of ~3.5 keV seen toward a number of astrophysical sites have been reported. If this signal will be confirmed to be the signature of decaying DM sterile neutrino with a mass of ~7.1 keV, then the cosmological observables should be consistent with its properties. We compute the radiation and matter perturbations including the full resonance sweep solution for active - sterile neutrino flavor conversion and place constraints on the cosmological parameters and sterile neutrino properties by using most of the present cosmological measurements. We find the sterile neutrino upper limits for mass and mixing angle of 7.86 keV (equivalent to 2.54 keV thermal mass) and 9.41 x 10^{-9} (at 95% CL) respectively, for a lepton number per flavor of 0.0042, that is significantly higher than that inferred in Abazajian (2014) from the linear large scale structure constraints. This reflects the sensitivity of the high precision CMB anisotropies to the helium abundance yield which in turn is set by the electron neutrino lepton number and the non-thermal active neutrino spectra. Other cosmological parameters are in agreement with the predictions of the minimal extension of the base LambdaCDM model except for the active neutrino total mass uper limit that is decreased to 0.21 eV (95% CL).
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• "[71] [72] [73]. The latest CMB results of WMAP, SPT [74] and ACT [75] combined with BAO and HST gave N eff = 3.84 ± 0.40 at 68% C.L. [76]. Thus, although somehow controversial [77], rather than a constraint there seemed to be a 2-σ preference for a non-negligible amount of unaccounted dark radiation [78]. "
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ABSTRACT: We compute the thermalisation of a hidden sector consisting of minicharged fermions (MCPs) and massless hidden photons in the early Universe. The precise measurement of the anisotropies of the cosmic microwave background (CMB) by Planck and the relic abundance of light nuclei produced during big bang nucleosynthesis (BBN) constrain the amount of dark radiation of this hidden sector through the effective number of neutrino species, \neff. This study presents novel and accurate predictions of dark radiation in the strongly and weakly coupled regime for a wide range of model parameters. We give the value of \neff for MCP masses between \$\sim\$ 100 keV and \$10\$ GeV and minicharges in the range \$10^{-11}-1\$. Our results can be used to put bounds on MCPs from the current data and it is also a valuable indicator for future experimental searches, should the hint for dark radiation manifest itself in the next release of Planck's data.
Journal of Cosmology and Astroparticle Physics 11/2013; 2014(02). DOI:10.1088/1475-7516/2014/02/029 · 5.88 Impact Factor
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• "These times refer to a rapid expansion of Universe, which is called the inflation [3] [4] [5] [6] [7] that is supported by certain real facts in its favor. So, the observed magnitude and spectrum of anisotropy in the cosmic microwave background radiation [19] [20] [21] [22] can be explained dynamically, instead of introducing an occasional set of very specific initial data of evolution. "
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ABSTRACT: The artificial scale of observable cosmological constant is dynamically related to its natural bare value due to the evolution of relevant coherent state for the inflationary field in the early Universe, because of exponential suppression of probability to find the state with zero number of quanta. Homogeneous quantum fluctuations of the field actually put hard constraints on the total amount of inflation.