Zou Zhen-long

A statistical study of the Lyman-Alpha absorption lines of nine quasars

Abstract We investigate the properties of the L α absorption lines in the high resolution spectra of nine quasars, B2 1225+31.7, PKS 2126-158, Q 0002-422, Q 1453-423, PHL 957, PKS 0528-250, PKS 0805+046, PKS 1448-232 and PKS 1442+101. Their emission line redshift range is 2.20 ⩽ z em ⩽ 3.54; a total of 350 L α absorption lines cover the range 1.70 ⩽ z abs ⩽ 3.54. Our analysis support the following conclusions; 1) the number density of L α absorption lines is not significantly different in different quasars. 2) The number density does not vary significantly with redshift. 3) Their equivalent width spectrum does not vary significantly with redshift. 4) Their properties are the same whether in the wing of the L α emission or in the continuum. 5) Their two-point correlation function is flat within the limit of resolution, which is different from the behaviour of galaxies. These results show that the L α absorption lines in high-redshift quasars are very probably produced by intergalactic hydrogen clouds uniformly distributed throughout space.

Correlation between the Lyman alpha absorption line density and the emission line redshift of QSOs

Abstract A statistical analysis of the absorption line density N(zabs) in the Lαforest of 16 high-redshift quasars shows that the line density is clearly dependent on the emission redshift of the quasar, zem. Not only is the mean density of all the Lα absorption lines larger for larger zem, but more importantly, for each given absorption redshift interval, N(zabs) is also positively correlated with zem. A two-factor variance analysis, with ejection velocity as the second factor, shows that the line density in the Lα forest depends sensitively on zem but not on the ejection velocity. These results are difficult to interpret by either the intervening or the ejecting hypothesis and are unlikely to be due to the selection effects suggested by Carswell et al. [13].

A Finite Temperature λϕ4 Model and De Sitter-Friedmann Phase Transition in the Early Universe

In this paper, we propose a simple finite temperature λ4 cosmological model to show that a new type singularity free cosmological model could be established by taking a series of important quantum and statistical effects into consideration such as spontaneous symmetry breaking, trace anomaly and particle creation, symmetry restoration at high temperature through phase transition and others. To begin with, the state of the universe would be a cold singu1arity free and horizon free Beltrami-Anti de Sitter one rather than a hot one. Then associated with the, particle creation, the temperature would, become higher and higher and as soon. as the temperature reached a critical value, Tc, a second-order phase transition would take place and the universe would transfer to a hot radiation dominated Friedmann state.

High resolution maps of two southern radio galaxies 1331-09 and 1417-20

Abstract Two southern radio galaxies 1331-09 and 1417-20 have been observed with the Fleurs synthesis radio telescope at 1415 MHz. The deduced geometrical and physical parameters show that 1331-09 is a giant radio galaxy having two outer components extending 1.9 Mpc and a central component coinciding with its optical counterpart. Many similarities of its features to CygA suggest that hot spots structure at the outer edge of its components should be expected in a higher resolution map. The source 1417-20 is a rather typical radio galaxy with halo-nucleus structure.

Method of density moment sums for photometric calibration of photographic plates

Abstract A new method — the method of moment density sums — is suggested for determining the characteristic curve of a plate as well as the magnitude zero point, using PDS microdensitometer measurements of stars of known brightness. It may be used for surface photometry of plates without sensitometer spots.

A spherically symmetric star model in the gravitational gauge theory

Abstract It is shown that starting from the gravitational gauge theory, it is possible to establish a star model free from black holes and singularities, under the condition of a torsion-less spacetime and spin-less matter. Thus, in a certain sense, this paper shows that discussions on black holes and singularities based on general relativity very possibly do not correspond to realities in nature.

The environment of seyfert galaxies

Abstract We made a nearest neighbour analysis on the cluster galaxies in the CfA sample. We found that galaxies with nearest distances below 20 kpc show a clear excess of Seyfert nuclei (i.e., the incidence of Seyferts among such galaxies is about 3 times higher than the average). This shows that the existence of nearby galaxies probably provides a favourable environment for generating Seyfert type activities.

Photoelectric and spectral observations of Vela X-1 during the time of sudden changes in its x-ray pulse period

Abstract This paper gives the results of narrow-band (Hγ and Hδ) photoelectric photometry of Vela X-1 made in February 1981 and discusses the possible periods from a spectral analysis. Spectral data in the same object obtained in April 1980 are also given. There appears to be clear correlations when compared with the sudden change in its X-ray pulse period during this time.

On the Neutrino Mass, the Abundance of Right-Handed Neutrino and the Closeness of the Universe

We point out that although the neutrino mass is finite, the left-handed neutrino density still dominates over the right-handed one in the universe unless there exists one or more elementary fernions (quark or lepton) whose mass is larger than 106 GeV. or . (MWL and MWR are the left and right handed intermediate boson respectively).If there exists neutrino the mass of which is about 34 ev. as indicated in some experiments, then one can conclude that the total neutrino mass of the universe s, should contribute about 99% to the whole masses and lead to the closeness of the universe. This conclusion can be brought to the agreement of all observation data which have been obtained so far. A mass limit of all species of neutrinos obtained by reexamining all data is Σimνi ≤ 200 eV

A finite temperature λφ4 model and A De Sitter — Friedmann transition in the early universe

Abstract We have analysed the finite temperature λφ4 model in the Robertson Walker metric, taking into consideration spontaneous symmetry breaking, particle production and symmetry recovery through phase transition under a high temperature, and found that it is possible to have a cosmological model free of singularities. Such a model begins in the singularity-free, horizon-free, Beltrami-Anti-de Sitter state. Continual production of particles keeps on raising its temperature until a critical temperature TC is reached, when a phase change takes place, and the universe is transformed into a radiation-dominated, thermally-expanding Friedmann state. This phase transition corresponds to a big-bang without, however, an antecedent singularity.