Xiang Shou-Ping

Protruding Structure Buried in Radio Map by Wavelet

An efficient method to identify supernova remnants is provided, in order to iron out the great gap between the predicted number and the observed. We make an attempt to apply D4 wavelet to detect the useful structures buried in radio map, showing that it is an efficient way to separate noises from signals.

Small-scale anisotropy of microwave background radiation computed by means of the transfer function betweenz=2000 andz=800

We use the transfer function betweenz=2000 andz=800, to compute the small-scale anisotropy of the microwave background radiation (MBR). Then the numerical input is minimized and most physical effects are computed on analytical bases. The different slopes of the spectrum are used to account for different mass scales. The numerical results show that the dependence of ΔT/T on the spectrum indexn is not monotonic but rather different for the two regimes ofn<2 andn>2: forn<2 the curves with largern will be higher than that with smallern, while forn>2 the curves with largern will go down. The highest curve corresponds ton=2.

Density perturbations in a two-fluid component Universe

In a two-fluid component universe consisting of visible matter and neutrinos, the developed features of perturbations in the two components are quite different. If the densities ρ1 and ρ2, and the Jeans lengths λ1J and λ2J of the two components satisfy the relations ρ1≪ρ2, λ1J≪λ2J, the developed inhomogeneities in the non-dominant component 1 are larger than those in the dominant component 2. Moreover, the increase of perturbations is in some situations not monotonous but oscillatory, and such oscillations in the two components are contrary.

Scale-scale correlation as discriminant among the biased galaxy formation models

Using the mock galaxy catalogues created from the N-body simulations, various biasing prescriptions for modelling the relative distribution between the galaxies and the underlying dark matter are statistically tested by using scale-scale correlation. We found that the scale-scale correlation is capable of breaking the model degeneracy indicated by the low-order clustering statistics, and could be taken as an effective discriminant among a variety of biasing models. Particularly, comparing with the APM bright galaxy catalogue, we infer that the two parameter Lagrangian biasing model gives the best fit to the observed clustering features.

Large scale peculiar velocities of galaxies

Abstract We have calculated in detail the distribution of large scale peculiar velocities on assuming gaussian primordial mass perturbation and spherical symmetry, instead of the linear perturbaton approximation and window function used in usual fluid models. Calculation was made for several model universes dominated by various kinds of matter. The expected values of the peculiar velocities was found to decrease with increasing distance scale, in agreement with the conventional fluid and cosmic string models. For all acceptable parameter values our model is unable to explain the observed high peculiar velocity on a scale of 60 h−1 Mpc (Dressler et al. 1987). A reasonable explanation for the discrepancy is that there may be a region of huge mass concentration at a distance above 60 h−1 Mpc away from the Local Group.

Apparent superluminal expansion in a quasar neutrino halo

We deduce the apparent velocity formula of general relativity for a source moving in a spherical neutrino halo and show that, considering gravitational effects on the motion of photons, the neutrino halo around a quasar may cause apparent superluminal phenomena. Sample calculations illustrating this result are shown.

Superluminal separation caused by gravitational lens' effect of neutrino objects

Neutrino objects can cause the apparent superluminal separation in quasars as gravitational lenses. In this paper we analyse this possibility and calculate the differential bending for different equilibrium configurations of neutrino objects.

The line profile of a relativistic Keplerian ring in a massive neutrino halo

Abstract If a massive neutrino halo transparent to light surrounds a compact body (galactic nucleus or black hole), then the strong gravitational field inside the halo will radically alter the spectral line profiles of a light-emitting Keplerian ring. This paper gives precise solutions of the spectral profile in a core-halo structure of matter and neutrino, and the result is compared with the no-halo case. The distribution of the neutrino mass is also given under typical circumstances.

The equilibrium structure of loaded rotating polytropes

Abstract The equilibrium structure of rotating polytropes with a compact core has been studied by means of Chandrasekhars first-order perturbation theory. Several numerical solutions are given. The results show that the larger the core mass, the smaller the critical central angular velocity will be, and for the same angular velocity, the larger the core mass, the more oblate the rotation ellipsoid will be.