In this work, we constrain the spectral index nt of the primordial gravitational wave power spectrum in a universe with sterile neutrinos by using the Planck temperature data, the WMAP 9-year polarization data, the ba...In this work, we constrain the spectral index nt of the primordial gravitational wave power spectrum in a universe with sterile neutrinos by using the Planck temperature data, the WMAP 9-year polarization data, the baryon acoustic oscillation data, and the BICEP2 data. We call this model the ACDM＋r＋vs＋nt model. The additional massive sterile neutrino species can significantly relieve the tension between the Planck and BICEP2 data, and thus can reduce the possible effects of this tension on the fit results of nt. To constrain the parameters of sterile neutrino, we also utilize the Hubble constant direct measurement data, the Planck Sunyaev-Zeldovich cluster counts data, the Planck CMB lensing data, and the cosmic shear data. We find that due to the fact that the BICEP2 data are most sensitive to the multipole （ - 150 corresponding to k - 0.01 Mpc^-1, there exists a strong anticorrelation between nt and r0.0o2 in the BICEP2 data, and this further results in a strongly blue-tilt spectrum. However, a slightly red-tilt tensor power spectrum is also allowed by the BICEP2 data in the region with larger value of r0.00z. By using the full data sets, we obtain mvisterile ^eff = 0.48 -0.13^＋0.11 eV, Near = 3.73 -0.37^＋0.34, and nt = 0.96 -0.63^ ＋0.48 for the ACDM＋r＋vs＋nt model.展开更多
The validity of distance duality relation, η = D L (z)(1 + z) 2 /D A (z) = 1, an exact result required by the Etherington reciprocity theorem, where D A (z) and D L (z) are the angular and luminosity distances, plays...The validity of distance duality relation, η = D L (z)(1 + z) 2 /D A (z) = 1, an exact result required by the Etherington reciprocity theorem, where D A (z) and D L (z) are the angular and luminosity distances, plays an essential part in cosmological observations and model constraints. In this paper, we investigate some consequences of such a relation by assuming η a constant or a function of the redshift. In order to constrain the parameters concerning η, we consider two groups of cluster gas mass fraction data including 52 X-ray luminous galaxy clusters observed by Chandra in the redshift range from 0.3 to 1.273 and temperature range T gas > 4 keV, under the assumptions of two different temperature profiles. We find that the constant temperature profile is in relatively good agreement with no violation of the distance duality relation for both parameterizations of η, while the one with temperature gradient (the Vikhlinin et al. temperature profile) seems to be incompatible even at 99% CL.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 11175042)the National Ministry of Education of China (Grant No. N120505003)
文摘In this work, we constrain the spectral index nt of the primordial gravitational wave power spectrum in a universe with sterile neutrinos by using the Planck temperature data, the WMAP 9-year polarization data, the baryon acoustic oscillation data, and the BICEP2 data. We call this model the ACDM＋r＋vs＋nt model. The additional massive sterile neutrino species can significantly relieve the tension between the Planck and BICEP2 data, and thus can reduce the possible effects of this tension on the fit results of nt. To constrain the parameters of sterile neutrino, we also utilize the Hubble constant direct measurement data, the Planck Sunyaev-Zeldovich cluster counts data, the Planck CMB lensing data, and the cosmic shear data. We find that due to the fact that the BICEP2 data are most sensitive to the multipole （ - 150 corresponding to k - 0.01 Mpc^-1, there exists a strong anticorrelation between nt and r0.0o2 in the BICEP2 data, and this further results in a strongly blue-tilt spectrum. However, a slightly red-tilt tensor power spectrum is also allowed by the BICEP2 data in the region with larger value of r0.00z. By using the full data sets, we obtain mvisterile ^eff = 0.48 -0.13^＋0.11 eV, Near = 3.73 -0.37^＋0.34, and nt = 0.96 -0.63^ ＋0.48 for the ACDM＋r＋vs＋nt model.
基金supported by the National Natural Science Foundation of China under the Distinguished Young Scholar (Grant Nos.10825313 and 11073005)the Ministry of Science and Technology National Basic Science Program (Project 973) (Grant No.2012CB821804)+1 种基金the Fundamental Research Funds for the Central UniversitiesScientific Research Foundation of Beijing Normal University
文摘The validity of distance duality relation, η = D L (z)(1 + z) 2 /D A (z) = 1, an exact result required by the Etherington reciprocity theorem, where D A (z) and D L (z) are the angular and luminosity distances, plays an essential part in cosmological observations and model constraints. In this paper, we investigate some consequences of such a relation by assuming η a constant or a function of the redshift. In order to constrain the parameters concerning η, we consider two groups of cluster gas mass fraction data including 52 X-ray luminous galaxy clusters observed by Chandra in the redshift range from 0.3 to 1.273 and temperature range T gas > 4 keV, under the assumptions of two different temperature profiles. We find that the constant temperature profile is in relatively good agreement with no violation of the distance duality relation for both parameterizations of η, while the one with temperature gradient (the Vikhlinin et al. temperature profile) seems to be incompatible even at 99% CL.
