Mapping the universe in three dimensions

The determination of the three-dimensional layout of galaxies is critical to our understanding of the evolution of galaxies and the structures in which they lie, to our determination of the fundamental parameters of cosmology, and to our understanding of both the past and future histories of the universe at large. The mapping of the large scale structure in the universe via the determination of galaxy red shifts (Doppler shifts) is a rapidly growing industry thanks to technological developments in detectors and spectrometers at radio and optical wavelengths. First-order application of the red shift-distance relation (Hubble’s law) allows the analysis of the large-scale distribution of galaxies on scales of hundreds of megaparsecs. Locally, the large-scale structure is very complex but the overall topology is not yet clear. Comparison of the observed red shifts with ones expected on the basis of other distance estimates allows mapping of the gravitational field and the underlying total density distribution. The next decade holds great promise for our understanding of the character of large-scale structure and its origin.

Superluminal sources.

Predictions for the apparent velocity statistics under simple beaming models are presented and compared to the observations. The potential applications for tests of unification models and for cosmology (source counts, measurements of the Hubble constant H0 and the deceleration parameter q0) are discussed. First results from a large homogeneous survey are presented. The data do not show compelling evidence for the existence of intrinsically different populations of galaxies, BL Lacertae objects, or quasars. Apparent velocities betaapp in the range 1-5 h-1, where h = H0/100 km.s-1.Mpc-1 [1 megaparsec (Mpc) = 3.09 x 10(22) m], occur with roughly equal frequency; higher values, up to betaapp = 10 h-1, are rather more scarce than appeared to be the case from earlier work, which evidently concentrated on sources that are not representative of the general population. The betaapp distribution suggests that there might be a skewed distribution of Lorentz factors over the sample, with a peak at gammab approximately 2 h-1 and a tail up to at least gammab approximately 10 h-1. There appears to be a clearly rising upper envelope to the betaapp distribution when plotted as a function of observed 5-GHz luminosity; a combination of source counts and the apparent velocity statistics in a larger sample could provide much insight into the properties of radio jet sources.

Cosmological perturbations in coherent oscillating scalar field models

The fact that fast oscillating homogeneous scalar fields behave as perfect fluids in average and their intrinsic isotropy have made these models very fruitful in cosmology. In this work we will analyse the perturbations dynamics in these theories assuming general power law potentials V(ϕ) = λ|ϕ|^n /n. At leading order in the wavenumber expansion, a simple expression for the effective sound speed of perturbations is obtained c_eff^ 2  = ω = (n − 2)/(n + 2) with ω the effective equation of state. We also obtain the first order correction in k^ 2/ω_eff^ 2 , when the wavenumber k of the perturbations is much smaller than the background oscillation frequency, ω_eff. For the standard massive case we have also analysed general anharmonic contributions to the effective sound speed. These results are reached through a perturbed version of the generalized virial theorem and also studying the exact system both in the super-Hubble limit, deriving the natural ansatz for δϕ; and for sub-Hubble modes, exploiting Floquet’s theorem.

Measurement of the muon neutrino inclusive charged-current cross section in the energy range of 1–3 GeV with the T2K INGRID detector

We report a measurement of the νµ-nucleus inclusive charged current cross section (=σ cc) on ironusing data from exposed to the J-PARC neutrino beam. The detector consists of 14 modules in total, which are spread over a range of off-axis angles from 0◦ to 1.1◦. The variation in the neutrino energy spectrum as a function of the off-axis angle, combined with event topology information, is used to calculate this cross section as a function of neutrino energy. The cross section is measured to be σcc(1.1 GeV) = 1.10±0.15 (10^−38cm^2/nucleon), σcc(2.0 GeV) = 2.07±0.27 (10^−38cm^2/nucleon), and σcc(3.3 GeV) = 2.29 ± 0.45 (10^−38cm^2/nucleon), at energies of 1.1, 2.0, and 3.3 GeV, respectively. These results are consistent with the cross section calculated by the neutrino interaction generators currently used by T2K. More importantly, the method described here opens up a new way to determine the energy dependence of neutrino-nucleus cross sections.

The scale of the universe, by Harlow Shapley ... and Heber D. Curtis.

Mode of access: Internet.

Extreme ultraviolet explorer : long look at the next window.

Cover title.

Extreme ultraviolet explorer : a view inside the bubble.

Cover title.

Story of creation : a plain account of evolution /

Mode of access: Internet.

Histoire du ciel : ou lon recherche l'origine de lidolatrie et les méprises de la philosophie, sur la formation des corps célestes & de toute la nature : Tome second /

Mode of access: Internet.

Das Weltall : beschreibung und geschichte des kosmos im entwicklungskampfe der natur /

Mode of access: Internet.

The tomorrow of death; or, The future life according to science.

Mode of access: Internet.

Kosmos : Entwurf einer physischen Weltbeschreibung /

Mode of access: Internet.

Die Harmonie der Ergebnisse der Naturforschung mit den Forderungen des menschlichen Gemüthes; oder Die persönliche Unsterblichkeit als Folge der atomistischen Verfassung der Natur.

Mode of access: Internet.

God and the cosmic order,

Mode of access: Internet.

Das Weltproblem vom Standpunkte des relativistischen Positivismus : aus, historisch-kritisch Dargestellt /

Includes bibliographical references.