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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1982

Observer reference triad rotation, magnetic fields, and rotation in Euclidean cosmological models

It is shown that a cosmological model with Euclidean space sections admits fluid flows if a magnetic field is present. Further, if observer reference frames spin in their response to the universe, a vorticity may exist. Limits can be set on any present intergalactic magnetic field of less than 5.38 x 10 to the -10th gauss (for a model with the chosen symmetry and choice of initial field and fluid velocity components).

Fennelly, A. J.↗
NASA NTRS1981

Constraints on neutrinos and axions from cosmology

A review is made of the astrophysical arguments with regard to neutrino properties. It is shown that the best fit to the present baryon density and He-4 abundance is obtained with three neutrino species. It is also shown that astrophysical constraints on neutrino and axion lifetime-mass combinations rule out weakly interacting particles with lifetimes between 1/1000 to 10 to the 23rd sec for M up to 10 MeV. There is an allowed astrophysical window for neutrinos with M up to 10 MeV and tau less than 1000 sec. The possible role of massive neutrinos in the dark mass of galaxies is discussed. It is shown that the baryon density in the universe is comparable to the density obtained from the dynamics of binary galaxies. Therefore, massive neutrinos are only required if the cosmological mass density is greater than that implied by binaries and small groups of galaxies. The only objects which might imply such high densities are large clusters. For neutrinos to cluster with these large clusters requires a neutrino mass of at least 3 eV.

Schramm, D. N.↗
NASA NTRS1982

On the cosmological evolution of the X-ray emission from quasars

The average dependence of the ratio of X-ray luminosity to optical luminosity as a function of redshift and optical luminosity for quasars is derived, and it is found that the explicit dependence of this ratio is predominantly on optical luminosity. For a wide class of models for the cosmological evolution of quasars, the results imply that the evolution of the X-ray luminosity function is weaker than the evolution of the optical luminosity function. Implications for physical models of quasars and for global properties of the quasar population are indicated.

Avni, Y.↗
NASA NTRS1982

Cosmic ray antimatter and baryon symmetric cosmology

The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic-ray antiprotons, including the new low-energy measurement of Buffington, et al. We conclude that the cosmic-ray antiproton data may be evidence for antimatter galaxies and baryon symmetric cosmology. The present bar P data are consistent with a primary extragalactic component having /p=/equiv 1+/- 3.2/0.7x10 = to the -4 independent of energy. We propose that the primary extragalactic cosmic ray antiprotons are most likely from active galaxies and that expected disintegration of bar alpha/alpha ban alpha/alpha. We further predict a value for ban alpha/alpha =/equiv 10 to the -5, within range of future cosmic ray detectors.

Stecker, F. W.↗
NASA NTRS1983

Testing for a cosmological influence on local physics using atomic and gravitational clocks

The existence of a possible influence of the large-scale structure of the universe on local physics is discussed. A particular realization of such an influence is discussed in terms of the behavior in time of atomic and gravitational clocks. Two natural categories of metric theories embodying a cosmic infuence exist. The first category has geodesic equations of motion in atomic units, while the second category has geodesic equations of motion in gravitational units. Equations of motion for test bodies are derived for both categories of theories in the appropriate parametrized post-Newtonian limit and are applied to the Solar System. Ranging data to the Viking lander on Mars are of sufficient precision to reveal (1) if such a cosmological influence exists at the level of Hubble's constant, and (2) which category of theories is appropriate for a descripton of the phenomenon.

Adams, P. J.↗
NASA NTRS1984

Space telescope and cosmology

The status of institutional arrangements and of the hardware development for Space Telescope are highlighted. After a brief summary of instrument characteristics, some examples are given on the possible use of the ST to study objects of interest to cosmology.

Giacconi, R.↗
NASA NTRS1983

Luminosity function and cosmological evolution of X-ray selected quasars

The preliminary analysis of a complete sample of 55 X-ray sources is presented as part of the Medium Sensitivity Survey of the Einstein Observatory. A pure luminosity evolutionary law is derived in order to determine the uniform distribution of the sources and the rates of evolution for Active Galactic Nuclei (AGNs) observed by X-ray and optical techniques are compared. A nonparametric representation of the luminosity function is fitted to the observational data. On the basis of the reduced data, it is determined that: (1) AGNs evolve cosmologically; (2) less evolution is required to explain the X-ray data than the optical data; (3) the high-luminosity portion of the X-ray luminosity can be described by a power-law with a slope of gamma = 3.6; and (4) the X-ray luminosity function flattens at low luminosities. Some of the implications of the results for conventional theoretical models of the evolution of quasars and Seyfert galaxies are discussed.

Maccacaro, T.↗
NASA NTRS1985

Cosmological constraints on the lifetime of massive particles

Particles with masses more than a few MeV, decaying into photons or electrons, can cause destruction by photofission of cosmologically produced light elements. A previous calculation of this effect is corrected and extended, and used to derive maximum lifetimes for massive neutrinos; these range from a few thousand seconds upward, depending on the particle mass. Some approximate expressions are given that enable lifetime limits to be obtained for other particles, with different masses and abundances, such as gravitinos. These limits are generally stronger than previously determined constraints, such as distortion of the microwave background by energetic photons.

Lindley, D.↗
NASA NTRS1986

Studies of IRAS sources at high galactic latitudes. I - Source counts at /b/greater than 60 deg and evidence for a north-south anisotropy of cosmological significance

A study of the IRAS sky at b with an absolute value greater than 60 deg is conducted. Source counts at 12, 25, 60 and 100 microns are presented, and it is shown that emission from interstellar dust at 100 microns is localized to a few small areas of tathe galactic polar caps. At 12 and 25 microns, the sky is dominated by stars; at 60 and 100 microns, by galaxies. Comparison with the minisurvey source counts indicates the 12and 25-micron source denstiy is lower at the present latitude than at a latitude whereby the absolute value of b equals 10-40 deg. Due to the greatly reduced effects of emission from interstellar dust, the 100 micron survey reaches a factor 1.6 deeper in flux at the present latitude than the minisurvey. An anisotropy significant at the 4-sigma level was found between the north and south galactic polar caps at 60 and 100 microns, after exclusion of the Virgo cluster and of the few remaining areas significantly affected by interstellar-dust emission. It is suggested that this anisotropy represents a cosmologically significant anisotropy in the galaxy distribution. The scale of associated inhomogeneity is of the order of at least 100(50/H)Mpc.

Rowan-Robinson, M.↗
NASA NTRS1986

Dark matter and cosmological nucleosynthesis

Existing dark matter problems, i.e., dynamics, galaxy formation and inflation, are considered, along with a model which proposes dark baryons as the bulk of missing matter in a fractal universe. It is shown that no combination of dark, nonbaryonic matter can either provide a cosmological density parameter value near unity or, as in the case of high energy neutrinos, allow formation of condensed matter at epochs when quasars already existed. The possibility that correlations among galactic clusters are scale-free is discussed. Such a distribution of matter would yield a fractal of 1.2, close to a one-dimensional universe. Biasing, cosmic superstrings, and percolated explosions and hot dark matter are theoretical approaches that would satisfy the D = 1.2 fractal model of the large-scale structure of the universe and which would also allow sufficient dark matter in halos to close the universe.

Schramm, D. N.↗
NASA NTRS1986

X-ray properties of QSOs and their cosmological implications

The dependences of the X-ray luminosities of QSOs on redshift and optical luminosities are examined using the data from the optically selected heterogeneous sample study (1982) and complete optically selected sample study (1985) of Avni and Tananbaum. It is observed that the heterogeneous sample is applicable to this type of analysis, that the X-ray luminosity is more dependent on the optical luminosity than the redshift luminosity, and that changes in the X-ray spectral index value from 0.0 to 0.5 do not affect the data. It is concluded that there are correlations between the X-ray and optical luminosities and the relative rates of X-ray and optical cosmological evolution.

Avni, Y.↗
NASA NTRS1986

Gamma-ray bursters at cosmological distances

It is proposed that some, perhaps most, gamma-ray bursters are at cosmological distances, like quasars, with a redshift of about 1 or 2. This proposition requires a release of supernova-like energy of about 10 to the 51st ergs within less than 1 s, making gamma-ray bursters the brightest objects known in the universe, many orders of magnitude brighter than any quasars. This power must drive a highly relativistic outflow of electron-positron plasma and radiation from the source. It is proposed that three gamma-ray bursts, all with identical spectra, detected from B1900 + 14 by Mazets, Golenetskii, and Gur'yan and reported in 1979, were all due to a single event multiply imaged by a gravitational lens. The time intervals between the successive bursts, 10 hr to 3 days, were due to differences in the light travel time for different images.

Paczynski, B.↗
NASA NTRS1986

Homogeneous cosmological models and new inflation

The promise of the inflationary-universe scenario is to free the present state of the universe from extreme dependence upon initial data. Paradoxically, inflation is usually analyzed in the context of the homogeneous and isotropic Robertson-Walker cosmological models. It is shown that all but a small subset of the homogeneous models undergo inflation. Any initial anisotropy is so strongly damped that if sufficient inflation occurs to solve the flatness and horizon problems, the universe today would still be very isotropic.

Turner, Michael S.↗
NASA NTRS1987

Kinematic tests of exotic flat cosmological models

Theoretical prejudice and inflationary models of the very early universe strongly favor the flat, Einstein-de Sitter model of the universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the universe which posses a smooth component of energy density. The kinematics of such models, where the smooth component is relativistic particles, a cosmological term, a network of light strings, or fast-moving, light strings is studied in detail. The observational tests which can be used to discriminate between these models are also discussed. These tests include the magnitude-redshift, lookback time-redshift, angular size-redshift, and comoving volume-redshift diagrams and the growth of density fluctuations.

Charlton, Jane C.↗
NASA NTRS1988

Clustering correlations and limits on cosmological gravitational waves

A cosmological background of gravitational waves induces angular deviations in the propagation of light traversing it. All observed astrophysical sources might therefore have varying apparent positions, with the time dependence set by the wave period. Wavelengths greater than a kiloparsec are examined, so the positions are frozen but in general correlated. Comparison with observed galaxy-galaxy n-point correlation functions provide a spectrum-independent limit on the energy density of gravitational waves with wavelengths between a few tens of kiloparsecs and a few hundred megaparsecs of Omega(GW) less than 0.001.

Linder, Eric V.↗
NASA NTRS1988

Cosmological quantum chromodynamics, neutron diffusion, and the production of primordial heavy elements

A simple one-dimensional model is used to describe the evolution of neutron density before and during nucleosynthesis in a high-entropy bubble left over from the cosmic quark-hadron phase transition. It is shown why cosmic nucleosynthesis in such a neutron-rich environment produces a surfeit of elements heavier than lithium. Analytical and numerical techniques are used to estimate the abundances of carbon, nitrogen, and heavier elements up to Ne-22. A high-density neutron-rich region produces enough primordial N-14 to be observed in stellar atmospheres. It shown that very heavy elements may be created in a cosmological r-process; the neutron exposure in the neutron-rich regions is large enough for the Ne-22 to trigger a catastrophic r-process runaway in which the quantity of heavy elements doubles in much less than an expansion time due to fission cycling. A primordial abundance of r-process elements is predicted to appear as an excess of rare earth elements in extremely metal-poor stars.

Applegate, J. H.↗
NASA NTRS1988

Inflation in a renormalizable cosmological model and the cosmic no hair conjecture

The possibility of having inflation in a renormalizable cosmological model is investigated. The Cosmic No Hair Conjecture is proved to hold for all Bianchi types except Bianchi IX. By the use of a conformal transformation on the metric it is shown that these models are equivalent to the ones described by the Einstein-Hilbert action for gravity minimally coupled to a set of scalar fields with inflationary potentials. Henceforth, it is proven that inflationary solutions behave as attractors in solution space, making it a natural event in the evolution of such models.

Maeda, Kei-Ichi↗
NASA NTRS1988

Cosmological cosmic strings

The effect of an infinite cosmic string on a cosmological background is investigated. It is found that the metric is approximately a scaled version of the empty space string metric, i.e., conical in nature. Results are used to place bounds on the amount of cylindrical gravitational radiation currently emitted by such a string. The gravitational radiation equations are then analyzed explicitly and it is shown that even initially large disturbances are rapidly damped as the expansion proceeds. The implications of the gravitational radiation background and the limitations of the quadrupole formula are discussed.

Gregory, Ruth↗