Observational background of TREDER'S gravitation theory in cosmology and the role of viscosity

Starting from solutions of TREDER'S field equations for a homogeneous and isotropic universe filled with incoherent matter (p = 0) relations between observation quantities are derived and discussed. The FRIEDMANN time is of the order of HUBBLE age, the deceleration parameter may principally possess any positive or negative value, hence it is also possible to explain any m,z-relation completely in the frame of this theory. A decision between EINSTEIN'S theory and TREDER'S by cosmological observations is impossible. – Considering a realistic medium which consists of particles and radiation, energy dissipation originating from bulk viscosity (due to the interaction of particles and quanta) prevents cosmological singularities. Thereby entropy, now present in form of relict radiation, is produced. This process generates large amounts of restmass-free energy in the phase of maximum contraction and therefore could as well explain the large luminosity of compact single objects (quasars?). Models with energy dissipation are not invariant with respect to time reflection t→ – t in contrast to EINSTEIN'S theory. If demanding the universe to be free from singularities the direction of cosmic time is uniquely determined. This demand then restricts the possible relations between observation data to the case q₀ = + 1 being in accord with the latest determination by SANDAGE .     

Conformal analogs of the Jordan-Brans-Dicke theory. I.

Recent cosmological observations of large-scale structures (red shift of type Ia supernovae) confirm that the universe is currently expanding at an accelerating rate and its dominant component is dark energy. This has stimulated the development of the theory of gravity and led to many alternative variants, including tensor-scalar ones. This paper deals with the role of conformal transformations in the Jordan-Brans-Dicke theory. Variants of intrinsic, conformally coupled, and Einstein representations are examined. In the Einstein representation an exact analytic solution for the standard cosmological model is obtained. It is expressed in terms of the relative energy contributions of ordinary matter Ω _m , the scalar field Ω _CK , and a term Ω_Λ related to the cosmological constant Λ . Information on the evolution of the universe for the case with a minimally coupled scalar field is given in the form of graphs.     

The MultiDark Database: Release of the Bolshoi and MultiDark cosmological simulations

We present the online MultiDark Database – a Virtual Observatory‐oriented, relational database for hosting various cos‐mological simulations. The data is accessible via an SQL (Structured Query Language) query interface, which also allows users to directly pose scientific questions, as shown in a number of examples in this paper. Further examples for the usage of the database are given in its extensive online documentation. The database is based on the same technology as the Millennium Database, a fact that will greatly facilitate the usage of both suites of cosmological simulations. The first release of the MultiDark Database hosts two 8.6 billion particle cosmological N‐body simulations: the Bolshoi (250 h^–1 Mpc simulation box, 1 h^–1 kpc resolution) and MultiDark Run1 simulation (MDR1, or BigBolshoi, 1000 h^–1 Mpc simulation box, 7 h^–1 kpc resolution). The extraction methods for halos/subhalos from the raw simulation data, and how this data is structured in the database are explained in this paper. With the first data release, users get full access to halo/subhalo catalogs, various profiles of the halos at redshifts z = 0–15, and raw dark matter data for one time‐step of the Bolshoi and four time‐steps of the MultiDark simulation. Later releases will also include galaxy mock catalogs and additional merger trees for both simulations as well as new large volume simulations with high resolution. This project is further proof of the viability to store and present complex data using relational database technology. We encourage other simulators to publish their results in a similar manner. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Bianchi type-VI0 cosmological models in certain theories of gravitation

Exact Bianchi type-VI₀ cosmological solutions to Einstein's equations are presented in vacuum and for stiff-matter in the normal gauge for Lyra's geometry and in scalar-tensor theories developed by Saez and Ballester (1985) and Lau and Prokhovnik (1986). Also cosmological solutions are obtained for pure massive strings (p-strings) and for pure geometric strings. The dynamical behaviour of the models have been discussed.     

Vacuum bianchi type V and VI0 cosmological models in a new scalar-tensor theory of gravitation

Vacuum Bianchi type V and VI₀ cosmological models obtained in a new scalar-tensor theory of gravitation proposed by Schmidtet al. Some physical properties of these models are also discussed.     

Das Korrespondenzprinzip in der Kosmologie. II. Klassische und relativistische Darstellungen der Weltmodelle

According to the equivalence between the FRIEDMANN equation of relativistic cosmology and the condition for the time-independence H = o of the HAMILTON ian H of an isotropic particle-system in the NEWTON ian mechanics (which equivalence is proved in the part I of our paper) we construct the corresponding classical HAMILTON ians to the relativistic world-models. Each cosmological model which is resulting from a physically meaningful gravitation theory must give a FRIEDMANN equation as the cosmological formulation of the time-independence condition of the energy H for the corresponding NEWTON ian N-particle system. In general relativity, EINSTEIN's field equations are including EINSTEIN's strong principle of equivalence and are giving the constance f = o and M = o of the gravitation-number f and of the mass M of the universe additional to FRIEDMANN's equation. – In special relativity, we have fM = o and this MILNE -universe is possessing a NEWTON ian and a general relativistic interpretation, too. – However, if the postulate together with the “cosmological principle” other principles about the world structure, too (p. e. MACH'S or DIRAC'S principle or the “perfect cosmological principle” by the steady-state cosmology), then EINSTEIN'S weak principle of equivalence can be fulfilled, only. In these world models the gravity-mass fM becomes a function of the cosmic time t [d/dt(fM) ± o] and this variability of fM is compatible with the constance H = o of the energy H of the NEWTON ian particle-system. For flat three-dimensional cosmological spaces (with H = Ḣ = o) a creation of rest-mass (M > o) is possible. This creation is the pecularity of the steady-state cosmos (with M > o, f = o) and of JORDAN'S cosmos (with M > o, f < o). The MACH -EINSTEIN -doctrine about the perfect determination of the inertia and of the space-time-metric by the cosmic gravitation is founded on the substitution of the NEWTON ian HAMILTON ian by a GAUSS -RIEMANN ian gravitation potential U^*(r_AB' v_AB) (TREDER 1972). Therefore, the FRIEDMANN equation for a universe with MACH'S principle is resulting from the analytical expression of the time-independence of this RIEMANNian potential U* = 0. In the case of such MACH-EINSTEIN's-Universes EINSTEIN'S condition 3fM = c8r between the mass A4 and the radius Y of the universe is valid additional to FRIEDMANN'S equation. For these universes, the EINSTEIN condition determinates the instantaneous value of the gravitation-number f. - The explicite form of the conditions H = o or h' = o gives the equation of motion for the cosmic fundamental particles with attraction and repulsion forces, generally.     

The new period of the intermediate polar V709 Cas

We present the results of 10 years of photometric CCD observations of the intermediate polar V709 Cas obtained by using different instruments during 2003–2013. We detected a new variability with a period of P_new = 0.^d016449979(5) which seems to be real. The spin variability is not clearly seen in all our data, so we are unable to study any evolution of the white dwarf rotation. From the best night (in 2010) we obtained a spin period of P_spin = 311.^s8(5). We analyzed the orbital variability using (O – C) analysis. We found no variations of the orbital period on a timescale of 10 years, but the linear fit to the (O – C) diagram shows that the value of the orbital period is P_orb = 0.^d2222123(6), which is close to the earlier published values. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Delay of emission from extragalactic gamma-ray burst sources as a test for selecting a model of the universe

We obtained an order-of-magnitude estimate for the dispersion of light caused by the effect of quantum fluctuations on the propagation of electromagnetic waves in four-dimensional spacetime. We calculated the delay of the photons from cosmological gamma-ray bursts (GRBs) for the flat, open, and closed cosmological models. This delay is attributable to the effect of expansion of the Universe on the propagation of a dispersive light wave in space. Analysis shows that the delay of GRB photons contains a regular component related to the expansion of the Universe. We conclude that cosmological models of the Universe can be selected by the delay of emission of various energies from GRBs; the accuracy of measuring the parameter Δt/ΔE _γ must be no lower than 10^?6 s MeV^?1.     

A self-consistent world model

The field equations of the generalized field theory constructed by Mikhail and Wanas have been applied to a well-established geometrical structure given earlier by H. P. Robertson in connection with the cosmological problem. A unique solution, representing a specified expanding Universe (withq ₀=0, ₀=0.75,k=–1) has been obtained. The model obtained has been compared with cosmological observations and with FRW-models of relativistic cosmology. It has been shown that the suggested model is free of particle horizons. The existence of singularities has been discussed.The two cases, when the associated Riemannian-space has a definite or indefinite metric are considered. The case of indefinite metric with signature (+ – – –) is found to be characterized byk=–1, while the case of +ve definite metric is characterized byk=+1. Apart from that difference, the two cases give rise to the same cosmological parameters. It has been shown that energy conditions are satisfied by the material contents in both cases.     

Once more on quasar periodicities

In an earlier paper Arp, Bi, Chu and Zhu investigated various quasar samples and recognized a periodicity of remarkable degree in them. Their conclusion was that the existence of such a periodicity is a counterevidence against the cosmological origin of quasar redshifts. Since this question is of great importance in a cosmological context, here we reanalyze some of the samples together with a galaxy sample of the pencil-beam survey of Broadhurstet al. Our result is that on the plane of cosmological parameters (₀, ₀) there is a non-negligible region where two quasar samples and the galaxy sample are simultaneously fairly periodic. Pure periodicity is still compatible with cosmological principles, at least on length scales much longer than the period length. So the regularities can fit into a cosmological context.     

Fluctations in the cosmic microwave background arising from low-frequency gravitational radiation

Intense low-frequency intergalactic gravitational radiation with wave lengths λ smaller than the HUBBLE distance λ_H ≌ 3000 (100/H₀) Mpc but not exceedingly small compared to λ_H. generates anisotropies in the microwave background radiation. One contribution results from the local wave field and produces mainly a quadrupole-type temperature variation on the sky. Available data on large-scale microwave fluctuations do not exclude appreciable amounts of gravitational background radiation in the Megaparsec wave band. A more sensitive test is provided by a second far-field contribution, which has a small angular scale. Its amplitude depends strongly on the ratio of the (present) rest mass density to the HUBBLE constant, if a cosmological origin of the blackbody radiation is assumed. In a low-density universe, pre-galactic COMPTON scattering of the blackbody radiation is not able to reduce the fluctuations caused by the low-frequency gravitational wave field. The recent small-scale data by PARIJSKIJ would allow only small amplitudes of gravitational waves with an energy density significantly below the critical cosmological density. On the other hand, in a high-density universe, the small angular scale fluctuation in the blackbody radiation is completely damped out, and a gravitational radiation cosmos reaching the critical density is admitted. Independent of the matter density, the data by PARIJSKIJ would confine gravitational background radiation to insignificant amplitudes if a discrete source model for the origin of the microwave background has to be assumed.     

Redshifts and the Hubble diagrams of Quasi-Stellar Objects

In order to investigate the nature of the redshifts of QSOs, Hubble diagrams have been plotted. First, [log (cz),m _v ] pairs have been plotted for a sample of 252 QSOs. This sample has been drawn from the recent catalogue (Burbidgeet al., 1977) of 633 QSOs after excluding those for which either the redshifts are uncertain or theV magnitudes are not known accurately. Before plotting,K-correction has been applied to theV magnitudes. A least-squares linear fit has been obtained for this plot and, as a result, we get a slope of 0.165±0.012 against 0.2 expected theoretically on the basis of the assumption that the QSOs are at cosmological distances implied by their redshifts. The discrepancy in the value of the slope has been attributed partly to the uncertainty in theK-correction and partly to the evolutionary effect. In order to eliminate the uncertainty due to theK-correction, [log (cz), logf(H)] pairs have been plotted for a sample of 52 QSOs and a least-squares linear fit has been obtained which has a slope of –0.497±0.076, in close agreement with the theoretically expected value of –0.5. This lends support to the hypothesis that the redshifts of the QSOs are cosmological in nature. Finally, the evolutionary effect has been examined, and we conclude that the QSOs do evolve in luminosity in course of time.     

Estimation of cosmological parameters from peculiar velocities of flat EDGE-ON galaxies

We estimate the values of the cosmological parameters using the data about peculiar velocities of 1493 flat edge-on spirals from the RFGC catalogue. The obtained values Ω _m = 0.21_{− 0.09} ^{+ 0.22}, σ₈ = 1.07_{− 0.24} ^{+ 0.28} differ from the WMAP values by approximately 2–3σ, but well agree with modern constraints on these parameters. Due to a strong correlation between these quantities the shape of the 1σ, 2σ and 3σ-boundaries are rather narrow. This gives us the opportunity to use this estimation to verify the corresponding values, obtained by different methods.     

Non-zero rest mass neutrinos and the cosmological constant

Recently it was pointed out that a non-zero cosmological constant can play a role in the formation of neutrino halos only in the case of neutrinos of very low rest mass (m _v <-0.1eV). However, phase-space considerations would requirem _v >50 eV if neutrinos dominate the missing mass in halos of large spiral galaxies and moreoverm _v >200 eV is implied in the case of dwarf spheroidals. These larger neutrino masses would be in conflict with observed constraints on the age of the Universe unless a cosmological constant is invoked.     

Constraining the cosmological time variation of the fine - structure constant

The variation of the fine-structure constant α = e ² / ħc can be probed by comparing the wavelength of atomic transitions from the redshift of quasars in the Universe and laboratory over cosmological time scales t ~ 10¹⁰ yr. After a careful selection of pairs of lines, the Thong method with a derived analytical expression for the error analysis was applied to compute the α variation. We report a new constraint on the variation of the fine-structure constant based on the analysis of the C_IV, N_V, Mg_II, Al_III, and Si_IV doublet absorption lines. The weighted mean value of the variation in α derived from our analysis over the redshift range 0.4939 ≤ z ≤ 3.7 is = ( 0.09 ± 0.07)×10⁻⁵. This result is three orders of magnitude better than the results obtained by earlier analysis of the same data on the constraint on Δα/α .     

Struktur und Entwicklung kompakter Radioquellen

A model is suggested which accounts for (i) the observed shape and angular variation of compact radio sources (especially the apparent superrelativistic velocities and the absence of contracting sources), (ii) the flux variation associated with the angular variation, and (iii) all the known cases of apparent occurence of surface brightness exceeding the theoretical upper limit provided by the inverse COMPTON effect, preserving the usual premises: cosmological origin of the redshift and incoherent synchrotron radiation of electrons. The model consists of a plasma ring expanding with moderate relativistic velocity. It provides two possibilities for estimating the distance of the sources by radio data: from the time dependence of the angular expansion and from the angular diameter and the shape of flux variation. In the context of cosmology this distances are „angular distances”︁ and therefore, if the redshift is also known, the HUBBLE constant or the acceleration parameter q₀ may be obtained. The second method is applied to BL Lac yielding approximately 6 Mpc. So the underlying galaxy would be a dwarf system of M ≈︂–13. The active nucleus of M ≈︂ – 16 is rather below the normal quasars. This seems very satisfactory in view of the short time scale of variations in BL Lac compared to the quasars.     

Intrinsic colour indices of Be stars obtained from 2MASS photometry

This paper is based on 2MASS photometry (J H K_s magnitudes) of 1172 Be stars. The observed mean intrinsic colours have been derived with aid of two‐colour diagrams for Be stars of luminosity classes Ie‐IIe, IIIe and IVe‐Ve. The obtained results are the first determinations of their intrinsic colours in the astronomical literature. The smoothed infrared colours are compared with those obtained for “normal” B stars. Several two‐colour diagrams and plots of observed and smoothed intrinsic colour versus spectral type of luminosity classes Ie‐IIe, IIIe and IVe‐Ve are presented. Generally the determined infrared intrinsic colours of Be stars (V – J)₀, (V – H)₀, and (V – K_s)_o differ substantially from those of “normal” B stars. It is found that the intrinsic colours of B stars are generally bluer than Be stars of corresponding spectral type and luminosity class. The mean absolute visual magnitude M_v of 528 Be stars for luminosity classes Iae, Ibe‐Iabe, IIe, IIIe and IVe‐Ve is derived from HIPPARCOS parallaxes. The M_v calibration is compared with the existing ones. The Be stars are generally brighter than “normal” B stars of corresponding spectral types. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Higher-dimensional vacuum bianchi-mixmaster cosmologies

We derive some new exact 7-dimensional cosmological solutions |R⊗ I ⊗N, whereN = I, II, VI₀, VII₀, VIII and IX are the various 3-dimensional Bianchi models. The solutions given are higher-dimensional generalizations of the mixmaster cosmologies. There is a strong influence of the extra spacesN, which results in a fundamental change of the 3-dimensional cosmology.     

Measuring ΩM and ΩΛ with long‐duration gamma‐ray bursts

Gamma‐ray bursts (GRBs) are one of the most luminous events in the Universe. In addition, the Universe itself is almost transparent to γ ‐rays, making GRBs detectable up to very high redshifts. As a result, GRBs are very suitable to probe the cosmological parameters. This work shows the potential of long‐duration GRBs for measuring the cosmological parameters Ω_M and Ω_Λ by comparing the observed log N ‐log P distribution with the theoretical one. Provided that the GRBs rate and luminosity function are well determined, the best values and 1σ confidence intervals obtained are Ω_M = 0.22^+0.05_–0.03 and Ω_Λ = 1.06^+0.05_–0.10. Finally, a set of simulations show the ability of the method to measure Ω_M and Ω_Λ (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Lymanα forests and the evolution of the universe

The Lyα forest absorption lines in the spectra of quasars are interpreted as caused by the crossings of the light beam with the walls of a bubble structure (expanding with the Hubble flow only). Then, the typical separation between the absorption lines is proportional to the mean size of the bubbles. The variable factor is the expansion rate H[z]. The Friedmann regression analysis of the observed line separations determines the density parameter ω₀ and the normalized cosmological term λ₀ = λc²/3H²₀ of the appropriate cosmological model: ω₀ = 0.014 ± 0.002, λ₀ = 1.080 ± 0.006. Depending on the Hubble parameter this method reveals the values of the present mean matter density pm,0 = 2.6 h² · 10⁻²⁸ kg m⁻³ and of the cosmological constant Λ = 3.77 h² · 10⁻⁵² m⁻² (with h = H₀/(100 km/s·Mpc)). According to our analysis all models with Λ = 0 must be excluded. The curvature of space is positive. The curvature radius R₀ is 3.3 times the Hubble radius (c/H₀). The age t₀ is 2.8 times the Hubble age (H₀⁻¹).