Showing papers on "Structure formation published in 1984"
39 citations
01 Jan 1984
TL;DR: The quantum theory of scalar perturbations in the isotropicly expanding universe is discussed in this article, where it is shown that zero-point initial fluctuations can result in galaxies only if the universe when near a cosmological singularity evolves through a de-Sitter stage of sufficient duration.
Abstract: The quantum theory of scalar perturbations in the isotropicly expanding Universe is discussed. Zero-point initial fluctuations can result in galaxies only if the Universe when near a cosmological singularity evolves through a de-Sitter stage of sufficient duration.
2 citations
01 Jan 1984
TL;DR: In this article, the authors describe the significance of such observations, the present observational status and the prospects for the future in the 3K cosmic microwave background in galaxy clusters, and describe the current observational status of these observations.
Abstract: Photons from the 3K cosmic microwave background originating at z ~ 1500 are inverse Compton scattered on passing through the hot (107 to 108K) gas in galaxy clusters. Photons from the Rayleigh-Jeans (λ ≫ 1mm) part of the spectrum are scattered to λ ≪ 1mm, thereby producing a reduction in radiation intensity at λ > 1mm. This microwave decrement or “cooling” in clusters has been actively pursued observationally in the 10 years since its prediction by Sunyaev and Zeldovich (1970, 1972). In this paper we will describe the significance of such observations, the present observational status and the prospects for the future.
1 citations
01 Jan 1984
TL;DR: In this article, the cosmic string-loop model is developed whereby super-massive string-loops form nucleation centres for galaxies, and the modes of formation and angular momentum properties of string loops suggest an explanation for the elliptical/spiral discontinuity.
Abstract: The cosmic string-loop model is developed whereby super-massive string-loops form nucleation centres for galaxies. Estimation of the interaction of string-loops with matter gives acceptable decay times and radiative power for (proto) galaxy cores. The modes of formation and angular momentum properties of string-loops suggest an explanation for the elliptical/spiral discontinuity and a modified Hubble tuning-fork sequence.
01 Jan 1984
TL;DR: In this paper, the contribution of normal galaxies to the cosmic diffuse y-radiation has been investigated and it was shown that this contribution is limited to less than 1% and can therefore be neglected.
Abstract: Theories to explain the origin of the cosmic diffuse y-ray background generally fall into one of two broad categories: those which attribute the emission to particle interactions in intergalactic space and those which attribute it to the summation of numerous, unresolved discrete sources, including normal field galaxies, active galactic nuclei and clusters of galaxies Strong support for the latter interpretation is given by recent measurements of y-ray emission from external galaxies, mainly Seyfert galaxies Their summed contribution has been evaluated elsewhere; here, instead, we use recent observational data on the y-ray emission from our own galaxy to estimate the' contribution of normal galaxies to the cosmic diffuse y-radiation Our result indicates that this contribution is limited to less than 01% and can therefore be neglected