Indication for Primordial Anisotropies in the Neutrino Background from the Wilkinson Microwave Anisotropy Probe and the Sloan Digital Sky Survey

Trotta, Roberto; Melchiorri, A.

doi:10.1103/physrevlett.95.011305

Cited by 81 publications

(91 citation statements)

References 28 publications

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“…The breaking of the N eff , ρ m degeneracy in WMAP data at low N eff is due to the impact of neutrino perturbations, and this is the effect that allowed for an indirect detection of these perturbations as reported in [33,34].…”

Section: Does This Explanation Hold Together Quantitatively?mentioning

confidence: 99%

How massless neutrinos affect the cosmic microwave background damping tail

et al. 2013

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We explore the physical origin and robustness of constraints on the energy density in relativistic species prior to and during recombination, often expressed as constraints on an effective number of neutrino species, N eff . Constraints from current data combination of Wilkinson Microwave Anisotropy Probe (WMAP) and South Pole Telescope (SPT) are almost entirely due to the impact of the neutrinos on the expansion rate, and how those changes to the expansion rate alter the ratio of the photon diffusion scale to the sound horizon scale at recombination. We demonstrate that very little of the constraining power comes from the early Integrated Sachs-Wolfe (ISW) effect, and also provide a first determination of the amplitude of the early ISW effect. Varying the fraction of baryonic mass in Helium, YP, also changes the ratio of damping to sound-horizon scales. We discuss the physical effects that prevent the resulting near-degeneracy between N eff and YP from being a complete one. Examining light element abundance measurements, we see no significant evidence for evolution of N eff and the baryon-to-photon ratio from the epoch of big bang nucleosynthesis to decoupling. Finally, we consider measurements of the distance-redshift relation at low to intermediate redshifts and their implications for the value of N eff .

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Section: Does This Explanation Hold Together Quantitatively?mentioning

confidence: 99%

How massless neutrinos affect the cosmic microwave background damping tail

et al. 2013

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“…The number of relativistic neutrino species influences the CMB power spectrum by changing the time of matter-radiation equality that enhances the integrated Sachs-Wolfe effect, leading to a higher first acoustic Doppler peak amplitude. Also, the temperature anisotropy of the neutrino background (the anisotropic stress) acts as an additional source term for the gravitational potential [43,44], changing the CMB anisotropy power spectrum at the level of ∼ 20%. The delay of the epoch of matter-radiation equality shifts the LSS matter power spectrum turnover position toward larger angular scales, suppressing the power at small scales.…”

Section: +023mentioning

confidence: 99%

WMAP five-year constraints on lepton asymmetry and radiation energy density: implications for Planck

Popa

Vasile

2008

J. Cosmol. Astropart. Phys.

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Abstract.In this paper we set bounds on the radiation content of the Universe and neutrino properties by using the WMAP-5 year CMB measurements complemented with most of the existing CMB and LSS data (WMAP5+All), imposing also self-consistent BBN constraints on the primordial helium abundance. We consider lepton asymmetric cosmological models parametrized by the neutrino degeneracy parameter ξ ν and the variation of the relativistic degrees of freedom, ∆N oth ef f , due to possible other physical processes occurred between BBN and structure formation epochs.We get a mean value of the effective number of relativistic neutrino species of N ef f = 3.256 +0.607 −0.641 (68% CL), bringing an important improvement over the similar result obtained from WMAP5+BAO+SN+HST data [57]. We also find a strong correlation between Ω m h 2 and z eq , showing that we observe N ef f mainly via the effect of z eq , rather than via neutrino anisotropic stress as claimed by the WMAP team [57].WMAP5+All data provides a strong bound on helium mass fraction of Y p = 0.2486 ± 0.0085 (68% CL), that rivals the bound on Y p obtained from the conservative analysis of the present data on helium abundance.For neutrino degeneracy parameter we find a bound of −0.216 ≤ ξ ν ≤ 0.226 (68%CL), that represent an important improvement over the similar result obtained by using the WMAP 3-year data.The inclusion in the analysis of LSS data reduces the upper limit of the neutrino mass to m ν < 0.419 eV (95% CL) with respect to the values obtained from the analysis from WMAP5-only data [56] and WMAP5+BAO+SN+HST data [57].We forecast that the CMB temperature and polarization measurements observed with high angular resolutions and sensitivities by the future Planck satellite will reduces the errors on ξ ν and Y p down to σ(ξ ν ) ≃ 0.089 (68% CL) and σ(Y p ) = 0.013 (68% CL) respectively, values fully consistent with the BBN bounds on these parameters.This work has been done on behalf of Planck-LFI activities.PACS numbers: CMBR theory, dark matter, cosmological neutrinos, big bang nucleosynthesis WMAP 5-year constraints on lepton asymmetry and radiation energy density: Implications for Planck2

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“…Relativistic particles affect the CMB and the matter power spectrum in two ways: a) through their anisotropic stress [34,5], and b) through their relativistic energy density which alters the epoch of matter radiation equality. The ratio of CMB peak heights constrains matter-radiation equality yielding a degeneracy between N eff and Ω m h 2 .…”

Section: Introductionmentioning

confidence: 99%

Neutrino constraints from future nearly all-sky spectroscopic galaxy surveys

Carbone

Verde

Wang

et al. 2011

J. Cosmol. Astropart. Phys.

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We examine whether future, nearly all-sky galaxy redshift surveys, in combination with CMB priors, will be able to detect the signature of the cosmic neutrino background and determine the absolute neutrino mass scale. We also consider what constraints can be imposed on the effective number of neutrino species. In particular we consider two spectroscopic strategies in the near-IR, the so-called "slitless" and "multi-slit" approaches, whose examples are given by future space-based galaxy surveys, as EUCLID for the slitless case, or SPACE, JEDI, and possibly WFIRST in the future, for the multi-slit case. We find that, in combination with Planck, these galaxy probes will be able to detect at better than 3-sigma level and measure the mass of cosmic neutrinos: a) in a cosmology-independent way, if the sum of neutrino masses is above 0.1 eV; b) assuming spatial flatness and that dark energy is a cosmological constant, otherwise. We find that the sensitivity of such surveys is well suited to span the entire range of neutrino masses allowed by neutrino oscillation experiments, and to yield a clear detection of non-zero neutrino mass. The detection of the cosmic relic neutrino background with cosmological experiments will be a spectacular confirmation of our model for the early Universe and a window into one of the oldest relic components of our Universe.

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Indication for Primordial Anisotropies in the Neutrino Background from the Wilkinson Microwave Anisotropy Probe and the Sloan Digital Sky Survey

Abstract: We demonstrate that combining Cosmic Microwave Background anisotropy measurements from the 1st year WMAP observations with clustering data from the SLOAN galaxy redshift survey yields an indication for primordial anisotropies in the cosmological Neutrino Background.

Cited by 81 publications

References 28 publications

How massless neutrinos affect the cosmic microwave background damping tail

How massless neutrinos affect the cosmic microwave background damping tail

WMAP five-year constraints on lepton asymmetry and radiation energy density: implications for Planck

Neutrino constraints from future nearly all-sky spectroscopic galaxy surveys

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