Liu Yong-zhen

Fractal structure in the large scale distribution of galaxies

Abstract We study the large scale structure of galaxy distribution from the fractal point of view using the CfA survey data. Main results are as follows: 1. Within certain ranges, the galaxy distribution is fractal with fractal dimension about 2.0. This result is different fron the value 1.2 – 1.4, expected from the galaxy two-point correlation function. 2. Galaxies of different luminosities show somewhat different fractal dimensions. This result indicates that they may correspond to different perturbation ranges in the early universe, in apparent agreement with thepredictions of biased galaxy formation theory. 3. Scales smaller and greater than 10 Mpc seem to have different fractal dimensions. A preliminary analysis of these results is included.

FRACTAL TURBULENCE AND THE ORIGIN OF THE GALAXIES AND OF THE LARGE-SCALE STRUCTURE

Observations show that the geometry of the large-scale distribution of galaxies is like a self-similar sponge which can be regarded as a fractal in fractal geometry (the Sierpinski sponge) with the fractal dimensionDf=3−γ, γ=1.7–1.8 is the index in the two-point correlation function.We suggest using a new scheme to explain the origin of galaxies and large-scale structure. In our model, we assume that the density perturbations in the early Universe are adiabatic, and once they come within the horizon, they might produce the vortices of the fractal turbulence because of the Thomson drag. A model of the fractal turbulence is also given in this paper. The results obtained show that the basic characteristics of the galaxies (massMg, angular momentumJg) and the large-scale structure (fractal dimensionDf) can be explained, if the spectrum of early perturbations is the scale-free Zeldovich spectrum.

Effect of non-zero rest-mass of neutrinos on clustering in the early universe

Abstract This paper discusses the effect of neutrinos with non-zero rest-mass on the clustering process in the early universe. The early universe is regarded as a two-component fluid, one component being the de-coupled neutrinos, and the other being matter and radiation, between the two there is only the gravitational coupling. The main conclusions are: (1) such neutrinos will cause clustering of matter before the epoch of re-combination; (2) the mass so clustered will be in the range of the mass of clusters of galaxies; (3) there exists a preferential clustering scale, corresponding to the earliest onset of Jeans instability; (4) if the rest-mass is below a certain value, then there will be no effect.

Characteristic actions? (s) in the structure of the universe and the problem of the origin of galaxies

From the characteristic actionsħ(s), we can derive various relations between the basic characteristic quantities of objects and the fundamental constants in known physical laws. The main physical processes which lead to the formation of objects should be included in some such reletions through the fundamental constants. The problem of the origin of galaxies has been considered on the basis of the theory of actionsħ(s). It has been shown that in addition to gravitational effect, the dissipation process of the adiabatic density perturbations arising from the Thomson scattering in the early universe is a crucial process in forming galaxies; and if the Hubble constant has a valueH0 ∼ 50 km s−1 Mpc−1, the protogalaxies might be formed just before recombination.

Response to Dersarkissian's comments on the structure of the Universe

We found that the structure of the Universe can be characterized by a set of actions ℏs. This means that some discontinuous phenomena in the Universe can be considered as ‘large-scale quantum effects’. The behaviour of matter on a typical scale is determined by the behaviour of matter on other scales through the interactions.

The phase shift between the stellar and gaseous arms in the spiral galaxies M81 and M51

Abstract In this paper, the phase shift between the stellar and gaseous arms in the spiral galaxies M81 and M51 has been computed. It is found that the calculated pattern of the spiral arms agree in general with the observational results of 21 cm radio emission.

Two-point correlation function, correlation fractal dimension and typical scales in the large-scale distribution of IRAS galaxies

Abstract We discuss relation between two-point correlation function and correlation fractal dimension and use the IRAS galaxy redshift survey as illustration. The large-scale (≳ 15–20h−1Mpc) distribution of the IRAS galaxies can neither be described by a simple power-law two-point correlation function, nor a simple fractal. It can be better represented by a multi-level fractal. One of the characteristics of multi-level fractal is the existence of typical scales, at which fractal level changes. Un-normalized count can be used to determine the typical scales effectively and precisely. The existence of typical scales is a challenge to the current models of structure formation.

Fractal turbulence and the origin of large scale structure

Observations show that the large scale distribution of galaxies is like a selfsimilar spong /1/. The term “sponge” is due to most of volume observed in the Universe being devoid of galaxies /2/. there are many voids (diameter at least 60 Mpc) in the Universe /3/.

Characteristic actions ħ(s) in the structure of the universe

AbstractIt is suggested that gravitationally bound systems in the Universe can be characterized by a set of actions ħ(s). The actions