The Wilkinson Microwave Anisotropy Probe (WMAP), launched in 2001, has mapped out the Cosmic Microwave Background with unprecedented accuracy over the whole sky. Its observations have led to the establishment of a simple concordance cosmological model for the contents and evolution of the universe, consistent with virtually all other astronomical measurements. The WMAP first-year and three-year data have allowed us to place strong constraints on the parameters describing the ACDM model. a flat universe filled with baryons, cold dark matter, neutrinos. and a cosmological constant. with initial fluctuations described by nearly scale-invariant power law fluctuations, as well as placing limits on extensions to this simple model (Spergel et al. 2003. 2007). With all-sky measurements of the polarization anisotropy (Kogut et al. 2003; Page et al. 2007), two orders of magnitude smaller than the intensity fluctuations. WMAP has not only given us an additional picture of the universe as it transitioned from ionized to neutral at redshift z approx.1100. but also an observation of the later reionization of the universe by the first stars. In this paper we present cosmological constraints from WMAP alone. for both the ACDM model and a set of possible extensions. We also consider tlle consistency of WMAP constraints with other recent astronomical observations. This is one of seven five-year WMAP papers. Hinshaw et al. (2008) describe the data processing and basic results. Hill et al. (2008) present new beam models arid window functions, Gold et al. (2008) describe the emission from Galactic foregrounds, and Wright et al. (2008) the emission from extra-Galactic point sources. The angular power spectra are described in Nolta et al. (2008), and Komatsu et al. (2008) present and interpret cosmological constraints based on combining WMAP with other data. WMAP observations are used to produce full-sky maps of the CMB in five frequency bands centered at 23, 33, 41, 61, and 94 GHz (Hinshaw et al. 2008). With five years of data, we are now able to place better limits on the ACDM model. as well as to move beyond it to test the composition of the universe. details of reionization. sub-dominant components, characteristics of inflation, and primordial fluctuations. We have more than doubled the amount of polarized data used for cosmological analysis. allowing a better measure of the large-scale E-mode signal (Nolta et al. 2008). To this end we describe an alternative way to remove Galactic foregrounds from low resolution polarization maps in which Galactic emission is marginalized over, providing a cross-check of our results. With longer integration we also better probe the second and third acoustic peaks in the temperature angular power spectrum, and have many more year-to-year difference maps available for cross-checking systematic effects (Hinshaw et al. 2008).

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Five-year wilkinson microwave anisotropy probe * observations: likelihoods and parameters from the wmap data

Primordial nucleosynthesis probes the Universe during its early evolution. Given the progress in exploring the constituents, structure, and recent evolution of the Universe, it is timely to review the status of Big Bang Nucleosynthesis (BBN) and confront its predictions, and the constraints that emerge from them, with those derived from independent observations of the Universe at much later epochs. Following an overview of the key physics that controls the synthesis of the elements in the early Universe, the predictions of BBN in the standard (and some nonstandard) models of cosmology and particle physics are presented. The observational data used to infer the primordial abundances are described, with an emphasis on the distinction between precision and accuracy. These are compared with the predictions, testing the internal consistency of BBN and enabling a comparison of the BBN-inferred constraints with those derived from the cosmic microwave background radiation and large scale structure data.

https://www.annualreviews.org/doi/pdf/10.1146/annurev.nucl.56.080805.140437

Primordial Nucleosynthesis in the Precision Cosmology Era

Primordial nucleosynthesis: From precision cosmology to fundamental physics

We derive big-bang nucleosynthesis (BBN) constraints on both unstable and stable gravitino taking account of recent progress in theoretical study of the BBN processes as well as observations of primordial light-element abundances In the case of unstable gravitino, we set the upper limit on the reheating temperature assuming that the primordial gravitinos are mainly produced by the scattering processes of thermal particles For stable gravitino, we consider B-ino, stau, and sneutrino as the next-to-the-lightest supersymmetric particle and obtain constraints on their properties Compared with the previous works, we improved the following points: (i) we use the most recent observational data, (ii) for gravitino production, we include contribution of the longitudinal component, and (iii) for the case with unstable long-lived stau, we estimate the bound-state effect of stau accurately by solving the Boltzmann equation

Big-bang nucleosynthesis and gravitinos

Context. The primordial nature of the Spite plateau is at odds with the WMAP satellite measurements, implying a primordial Li production at least three times higher than observed. It has also been suggested that A (Li) might exhibit a positive correlation with metallicity below [Fe/H]  ~  −2.5. Previous samples studied comprised few stars below [Fe/H] =  −3.Aims. We present VLT-UVES Li abundances of 28 halo dwarf stars between [Fe/H] =  −2.5 and  −3.5, ten of which have [Fe/H] We determined stellar parameters and abundances using four different T eff scales. The direct infrared flux method was applied to infrared photometry. Hα wings were fitted with two synthetic grids computed by means of 1D LTE atmosphere models, assuming two different self-broadening theories. A grid of Hα profiles was finally computed by means of 3D hydrodynamical atmosphere models. The Li i doublet at 670.8 nm has been used to measure A (Li) by means of 3D hydrodynamical NLTE spectral syntheses. An analytical fit of A (Li)3D,NLTE as a function of equivalent width, T eff , log g , and [Fe/H] has been derived and is made available.Results. We confirm previous claims that A (Li) does not exhibit a plateau below [Fe/H] =  −3. We detect a strong positive correlation with [Fe/H] that is insensitive to the choice of T eff estimator. From a linear fit, we infer a steep slope of about 0.30 dex in A (Li) per dex in [Fe/H], which has a significance of 2–3σ . The slopes derived using the four T eff estimators are consistent to within 1σ . A significant slope is also detected in the A (Li)–T eff plane, driven mainly by the coolest stars in the sample (T eff (Li)–[Fe/H] plane is not altered significantly. When the full sample is considered, the scatter in A (Li) increases by a factor of 2 towards lower metallicities, while the plateau appears very thin above [Fe/H] =  −2.8. At this metallicity, the plateau lies at $\rm\left\langle{{\it A}(Li)_{3D,NLTE}}\right\rangle=2.199\pm0.086$A(Li)3D,NLTE=2.199±0.086. Conclusions. The meltdown of the Spite plateau below [Fe/H]  ~  −3 is established, but its cause is unclear. If the primordial A (Li) were that derived from standard BBN, it appears difficult to envision a single depletion phenomenon producing a thin, metallicity independent plateau above [Fe/H] =  −2.8, and a highly scattered, metallicity dependent distribution below. That no star below [Fe/H] =  −3 lies above the plateau suggests that they formed at plateau level and experienced subsequent depletion.

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The metal-poor end of the Spite plateau - I. Stellar parameters, metallicities, and lithium abundances

The measurement of the cosmic microwave background has strongly constrained the cosmological parameters of the Universe. When the measured density of baryons (ordinary matter) is combined with standard Big Bang nucleosynthesis calculations, the amounts of hydrogen, helium and lithium produced shortly after the Big Bang can be predicted with unprecedented precision. The predicted primordial lithium abundance is a factor of two to three higher than the value measured in the atmospheres of old stars. With estimated errors of 10 to 25%, this cosmological lithium discrepancy seriously challenges our understanding of stellar physics, Big Bang nucleosynthesis or both. Certain modifications to nucleosynthesis have been proposed, but found experimentally not to be viable. Diffusion theory, however, predicts atmospheric abundances of stars to vary with time, which offers a possible explanation of the discrepancy. Here we report spectroscopic observations of stars in the metal-poor globular cluster NGC6397 that reveal trends of atmospheric abundance with evolutionary stage for various elements. These element-specific trends are reproduced by stellar-evolution models with diffusion and turbulent mixing. We thus conclude that diffusion is predominantly responsible for the low apparent stellar lithium abundance in the atmospheres of old stars by transporting the lithium deep into the star.

Ludmila Mashonkina

Papers

A probable stellar solution to the cosmological lithium discrepancy