Cosmological parameters

The main goal of the Planck instrument is to improve the accuracy of the measurement of the cosmic microwave background (CMB), in order to extract cosmological parameters that remain poorly constrained after the results of WMAP (Wilkinson microwave anisotropy probe) and of the best ground-based experiments. The basic idea of HFI-Planck is to use all the information contained in the CMB radiation, i.e. to perform a radiometric measurement limited by the quantum fluctuations of the CMB radiation itself. In these conditions, the accuracy is only limited by the number of detectors and by the duration of the observation. 

Since density and temperature are fixed functions of time during BBNS, the outcome of the relevant nuclear reactions is a function of the single cosmological parameter r]. 

Helium is the second most abundant element in the visible Universe and accordingly there is a mass of data from optical and radio emission lines in nebulae, optical emission lines from the solar chromosphere and prominences and absorption lines in spectra of hot stars. Further estimates are derived more indirectly by applying theories of stellar structure, evolution and pulsation. However, because of the relative insensitivity of Tp to cosmological parameters, combined with the need to allow for additional helium from stellar nucleosynthesis in most objects, the requirements for accuracy are very severe better than 5 per cent to place cosmological limits on Nv and better still to place interesting constraints on t] or One can, however, assert with confidence that there is a universal floor to the helium abundance in observed objects corresponding to 0.23 < Fp < 0.25. 

Balloon and WMAP satellite missions provide details of angular fluctuation spectrum of MWB, giving precise estimates of cosmological parameters. 

The cosmological parameters and a can be determined from the Hubble diagram, provided that we have some well-calibrated cosmological standard candle that can be observed across a wide range of redshifts. This is precisely the approach adopted by Riess et al. (1998) and Perhnutter et al. (1999) when they used the type la supernovas. Pilar Ruiz-Lapuente at the University of Barcelona and Renald Pain at the University of Paris both made contributions to this exemplary cosmological programme. 

Spergel, D.N., Verde, L., Peiris, H.V. et al. (2003) First-year wilkinson microwave anisotropy probe (WMAP) observations determination of cosmological parameters. Astrophysical Journal Supplement Series, 148, 175-94. 

Cluster studies provide a unique window on the Universe. Although clusters are the most massive collapsed systems in the Universe, with dynamical timescales of order 109 yrs in their cores, they are relatively young and remember the conditions from which they formed. Also, clusters form from rare overdensities. Therefore, cluster properties and numbers are sensitive to cosmological parameters. 

However, any estimation of the cosmological parameters gives some constraints on the ratio between matter and radiation. One has something like... 

In 10.4,1 will discuss the evolution of density perturbations in an expanding Universe and in 10.5 the plasma oscillations thereby induced. In 10.6 I will introduce that statistical tools to describe the distribution of CMB tem-pertatures on the sky, and in 10.7 how the cosmological parameters influence the distribution of temperatures. Finally, in 10.8 I will briefly review how we actually analyze CMB data and conclude in 10.8. 

All of these effects are included in codes like CMBFAST (Seljak and Zal-darriaga 1996 Zaldarriaga and Seljak, 2000, http //www.cmbfast.org/) and CAMB (Lewis et al., 2000, http //camb.info/) which solve the combined Boltzmann and linearized Einstein equations in an expanding Universe. These codes allow one to calculate the CMB temperature power spectrum for a given model. A sample of spectra for various input cosmological parameters is shown in Figure 10.2. 

Figure 10.2. A sample of theoretical power spectra for various cosmological parameters, as marked.

Cosmology with supernovae has developed over the second half of the last century. Their extreme luminosities always made them attractive candidates to measure large distances. Various methods were devised to use supernovae to measure cosmological parameters ranging from simple standard candle paradigms to physical explanations of the supernova explosions and subsequent derivation of distances. Essentially, supernovae have been used to determine luminosity distances, i.e. the comparison of the observed flux to the total emitted radiation. The trick is to find a reliable way to measure the absolute luminosity of the objects. 

From the previous equation it can be readily noted that the amplitude of the convergence held is expected to be both proportional to Qo and to the amplitude of the 3D mass density fluctuation. Extra dependence with the other cosmological parameters (Qo, Ga) can take place through the growth rate of the fluctuation and the cosmological distances if the source plane is at large enough redshift (comparable to unity). 

Snowden-Ifft, D. R, Martoff, C. J., Burwell, J. M. 2000. Low pressure negative ion drift chamber for dark matter search, Phys. Rev. D61, 101301 Spergel, D. N. Steinhardt, P J. 2000. Observational Evidence for Self-Interacting Cold Dark Matter, Phys. Rev. Lett. 84, 3760 Spergel, D. N., et al. 2003. First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations Determination of Cosmological Parameters, ApJS 148,175... 

Planck Collaboration. Planck 2015 results. XIII. Cosmological parameters. arXiv 1502.01589v2 [astro-ph.CO] 6 Feb 2015 67 pages. [Internet]. 2015. Available from xxx.lanl.gov/abs/1502.01589v2 or arxiv.org/abs/1502.01589v2 [Accessed 2015-12-05]. See Sects. 5.4 and 5.6. 

Figure 15. (Reproduced from http //astro.princeton.edu/ cen). Distribution of neutral gas at z = 3 from hydrodynamic cosmological simulation in a spatially flat, COBE-normalized, cold dark matter model with the cosmological parameters adopted in this article ( 1.1). The box size is 25Mpc/h (comoving) on the side, and the number of particles used in the simulation is 7683. The structure seen in this (and other similar simulations) reproduces very well the spectral properties of the Lya forest when artificial spectra are generated along random sightlines through the box.

A representative anthropic argument from carbon abundance relevant to multiverse cosmology uses the same variables with a slightly different interpretation. Suppose now that nuclear physics depends on the cosmological model through parameters (e.g. arbitrary features of consistent solutions to some more fundamental grand unified theory) and that N is the subset of parameter-independent features (rather than those that are simple to use). Then expand / to include the cosmological parameters that are theoretically variable, and suppose that structures such as. SX C) are predictable from N and X with some index function... 

The information concerning the constitution of the early Universe has increased tremendously during the past decade, mainly due to improved observations of the cosmic microwave background radiation (CMBR). The most important cosmological parameters (the total energy density, the part contained in baryonic matter, the part of nonbaryonic dark matter (DM), other components, etc.) have been determined with percent level accuracy as a result of projects completed in the first decade of the twenty-first century and now appear in tables of fundamental physical data (Amsler et al. 2008). 

An important prediction of the inflationary scenario for the origin of CMBR anisotropy is a sequence of maxima in the multipole spectrum (Hu 2001). The latest results (see Fig. 12.1) confirm the existence of at least two further maxima, in addition to the main maximum known before. The new satellite-based CMBR observations by the European satellite PLANCK launched in May 2009 will improve the accuracy of the deduced cosmological parameters to 0.5% and determine the multipole projection of the anisotropy up to angular momentum I 2,500. 

Starrfield S, Sparks WM, Truran JW, Wiescher MC (2000) Astrophys J Suppl 127 485 Starrfield S (1999) Phys Rep 311 371 Steigman G (2007) Ann Rev Nucl Part Sci 57 463 Steigman G, Walker TP, Zentner A (2000) Global constraints on key cosmological parameters, astro-ph/ 0012149. 

Energy CoUider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter. 

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