Planck intermediate results LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters

doi:10.1051/0004-6361/201629504

	Planck intermediate results LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters
	Aghanim, N.52; Akrami, Y.54,56; Ashdown, M.6,63; Aumont, J.52; Baccigalupi, C.78; Ballardini, M.29,44,47; Banday, A. J.9,91; Barreiro, R. B.58; Bartolo, N.28,59; Basak, S.84
刊名	ASTRONOMY & ASTROPHYSICS
	2017-11-20
卷号	607 页码:27
关键词	cosmology: observations cosmic background radiation cosmological parameters cosmology: theory
ISSN号	1432-0746
DOI	10.1051/0004-6361/201629504
通讯作者	Galli, S.(gallis@iap.fr) ; Millea, M.(millea@iap.fr)
英文摘要	The six parameters of the standard Lambda CDM model have best-fit values derived from the Planck temperature power spectrum that are shifted somewhat from the best-fit values derived from WMAP data. These shifts are driven by features in the Planck temperature power spectrum at angular scales that had never before been measured to cosmic-variance level precision. We have investigated these shifts to determine whether they are within the range of expectation and to understand their origin in the data. Taking our parameter set to be the optical depth of the reionized intergalactic medium tau, the baryon density omega(b), the matter density omega(m), the angular size of the sound horizon theta(), the spectral index of the primordial power spectrum, n(s), and A(s)e(-2 pi) (where As is the amplitude of the primordial power spectrum), we have examined the change in best-fit values between a WMAP-like large angular-scale data set (with multipole moment l < 800 in the Planck temperature power spectrum) and an all angular-scale data set (l < 2500 Planck temperature power spectrum), each with a prior on tau of 0.07 +/- 0.02. We find that the shifts, in units of the 1 sigma expected dispersion for each parameter, are {Delta tau, Delta A(s)e(-2 tau), Delta n(s), Delta omega(m), Delta omega(b), Delta theta()} = {-1.7, -2.2, 1.2, 2.0, 1.1, 0.9}, with a chi(2) value of 8.0. We find that this chi(2) value is exceeded in 15% of our simulated data sets, and that a parameter deviates by more than 2.2 sigma in 9% of simulated data sets, meaning that the shifts are not unusually large. Comparing l < 800 instead to l > 800, or splitting at a different multipole, yields similar results. We examined the l < 800 model residuals in the l > 800 power spectrum data and find that the features there that drive these shifts are a set of oscillations across a broad range of angular scales. Although they partly appear similar to the effects of enhanced gravitational lensing, the shifts in Lambda CDM parameters that arise in response to these features correspond to model spectrum changes that are predominantly due to non-lensing effects; the only exception is tau, which, at fixed A(s)e(-2 tau), affects the l > 800 temperature power spectrum solely through the associated change in As and the impact of that on the lensing potential power spectrum. We also ask, "what is it about the power spectrum at l < 800 that leads to somewhat different best-fit parameters than come from the full l range?" We find that if we discard the data at l < 30, where there is a roughly 2 sigma downward fluctuation in power relative to the model that best fits the full l range, the l < 800 best-fit parameters shift significantly towards the l < 2500 best-fit parameters. In contrast, including l < 30, this previously noted "low-l deficit" drives ns up and impacts parameters correlated with ns, such as omega(m) and H-0. As expected, the l < 30 data have a much greater impact on the l < 800 best fit than on the l < 2500 best fit. So although the shifts are not very significant, we find that they can be understood through the combined effects of an oscillatory-like set of high-l residuals and the deficit in low-l power, excursions consistent with sample variance that happen to map onto changes in cosmological parameters. Finally, we examine agreement between Planck TT data and two other CMB data sets, namely the Planck lensing reconstruction and the TT power spectrum measured by the South Pole Telescope, again finding a lack of convincing evidence of any significant deviations in parameters, suggesting that current CMB data sets give an internally consistent picture of the Lambda CDM model.
WOS关键词	PROBE WMAP OBSERVATIONS ; CMB ANISOTROPIES ; APPROXIMATION ; RADIATION ; UNIVERSE ; MAPS
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	EDP SCIENCES S A
WOS记录号	WOS:000415859600004
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/22088]
专题	中国科学院紫金山天文台
通讯作者	Galli, S.; Millea, M.
作者单位	1.Univ Paris Diderot, CNRS IN2P3, APC Astroparticule & Cosmol, CEA lrfu Observ Paris,Sorbonne Paris Cite, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France 2.African Inst Math Sci, 6-8 Melrose Rd, ZA-7945 Cape Town, South Africa 3.Agenzia Spaziale Italiana Sci Data Ctr, Via Politecn Snc, I-00133 Rome, Italy 4.Agenzia Spaziale Italiana, Via Politecn Snc, I-00133 Rome, Italy 5.Aix Marseille Univ, CNRS, LAM, F-13013 Marseille, France 6.Univ Cambridge, Cavendish Lab, Astrophys Grp, J J Thomson Ave, Cambridge CB3 0HE, England 7.Univ KwaZulu Natal, Sch Math Stat & Comp Sci, Astrophys & Cosmol Res Unit, Westville Campus,Private Bag X54001, ZA-4000 Durban, South Africa 8.Univ Toronto, CITA, 60 St George St, Toronto, ON M5S 3H8, Canada 9.CNRS, IRAP, 9 Av Colonel Roche,BP 44346, F-31028 Toulouse 4, France 10.CALTECH, Pasadena, CA 91125 USA
推荐引用方式 GB/T 7714	Aghanim, N.,Akrami, Y.,Ashdown, M.,et al. Planck intermediate results LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters[J]. ASTRONOMY & ASTROPHYSICS,2017,607:27.
APA	Aghanim, N..,Akrami, Y..,Ashdown, M..,Aumont, J..,Baccigalupi, C..,...&Zonca, A..(2017).Planck intermediate results LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters.ASTRONOMY & ASTROPHYSICS,607,27.
MLA	Aghanim, N.,et al."Planck intermediate results LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters".ASTRONOMY & ASTROPHYSICS 607(2017):27.