Chu Yao-quan

A statisical analysis of quasars with resolved radio components: I. The redshift-magnitude relation

Abstract In this paper a statistical investigation is made on the redshift-magnituderelation for quasars with resolved radio components. The main results are: 1. 1. The largest linear distance D between the components is an important parameter which can be used in a “standard candle” classification. 2. 2. Regression equations among redshift, apparent magnitude and D have been established with high correlation coefficients and consequently, the redshifts of these quasars are likely to be cosmological in the main. 3. 3. The redshift-distance relation was found expressible in the form r ∞ z − 0.19z2, which departs markedly from Hubbles linear relation when z > 1. 4. 4. The new redshift-distance relation also gives a tighter redshift-magnitude relation for the radio galaxies than Hubbles relation does. 5. 5. The optical luminosity of a quasar is the smaller, the larger its value of D.

Statistical analysis of quasars with resolved radio components II. Variations of absolute visual magnitude, absolute radio magnitude and color index difference Q with linear separation of components, some associated evolution features

Abstract Using the standard candle classification by means of the linear distance D between the components, described in Paper I of this series, we have succeeded in uncovering, amongst quasars with maximum angular sizes, the statistical relations between visual magnitude and redshift, and between D and the absolute visual and radio magnitudes and the color index differences Q. These relations point to the following evolutionary features: 1. 1. The optical liminosity decreases with increasing D . dM ν dD = 10 m .6/ Mpc . 2. 2. The radio luminosity decreases with increasing D . dM 408−5000 dD = 9 m .17 Mpc . 3. 3. The color index difference Q decreases with increasing D . dQ dD = −1 m .55/ Mpc . 4. 4. The radio spectral type, as defined by the spectral index, shows no evolution in general. 5. 5. The optical radiation is mainly non-thermal, but the thermal component increases as the quasar evolves. 6. 6. The evolution time scales, as estimated from the variations in optical and radio luminosities and Q, have about the same value of 16 × 10 6 y. 7. 7. The above features are consistent with the view that QSOs evolve to galaxies. 8. 8. There is no apparent dependence of D on distance, i.e. no evidence that all QSOs were formed at the same epoch. This is contrary to the views of big bang cosmologies.

Optical spectra and redshifts of 15 flat-spectrum radio sources

Abstract Optical spectra for 15 QSO candidates, selected from optical identifications of flat-spectrum radio sources, are presented. Six of them have obvious emission line features, which confirm them to be quasars. The largest redshift is 3.45 for PKS 0335-122. Selection effects in the search for quasars with redshifts greater than 3.5 are discussed.

Optical identifications of QSOs with flat radio spectra

Abstract Optical identifications of 35 “empty fields” in a radio sample with flat-spectra have been made by using TV and CCD camera at Kitt Peak National Observatory 4-m telescope. Based on close radio-optical position coincidence, 29 sources are identified with stellar objects. The new identified objects have more steep radio-optical spectra indices α ro . The statistical results suggest a correlation of the radio and optical luminosities.

Evidence for evolution in the clustering of quasars

Abstract We discuss the changes in the amplitude of the correlation function of quasar clustering with the redshift. Using the new Hewitt-Burbidge QSO catalogue, we find from a statistical analysis of the quasar pairs that the positive results of quasar clustering are mainly contributed by low-redshift quasars. There is an obvious change in the quasar distribution at z = 2. There is no clustering for z > 2. The difference in clustering is not due to any selection effect on the brightness. The evidence is that quasar clustering evolved with cosmological time.

Periodic redshift distribution of quasars associated with low — redshift galaxies

Abstract We applied power spectral analysis to the redshift distribution of the quasars associated with low-redshift galaxies. Periodicity is confirmed at a level of confidence >99%, with a period of Δ ln(1+ z ) = 0.206. This result is exactly the same as previously found for different quasar samples. The periodicity is not caused by any selection effect in the emission lines. The two phenomena, the periodicity in the redhsift distribution and the association of quasars with low-redhsift galaxies can both be rather well explained by a multiply-connected model of the universe.

DARK MATTER AND FORMATION OF LARGE SCALE STRUCTURE IN THE UNIVERSE ——THE TEST BY DISTRIBUTION OF QUASARS

According to the scenario, developed in the previous paper, on the formation of large scale structure in the universe, we would expect that: (ⅰ) the distribution of quasars should differ from that of galaxies because it has no strong inhomogeneity on the scale of 10—100 Mpc; (ⅱ) thte distributions of quasars with Z>2 and Z 2 quasars is rather homogeneous while the Z<2 quasars have a tendency to clustering.

Periodicity in the distribution of quasar redshifts and density perturbation in the early universe

Abstract We made a power spectrum analysis on the quasar emission redshift distribution, and further confirmed the existence of periodicity in respect of the quantity x = F ( z , q o ) defined at (8). The existence of this periodicity does not mean that the quasar redshift is non-cosmological, for it can be interpreted as a remnant of density (acoustic) perturbations in the early big-bang universe. For this model, we made a number of tests. We found: 1) the ratio of periodic to non-periodic components falls as the sample size increases; 2) the periodicity should be more marked for quasars in one region of the sky than for all quasars, and 3) the Jeans wavelength before the recombination epoch determines the length of the period. Using this model we also found that qo > 0.5, lending further support to the conclusion reached by other means that the universe may be closed.

A statistical analysis on the association of quasars and bright galaxies

Abstract We applied the nearest neighbour test in a statistical analysis on the association of quasars and bright galaxies. We found that the radio quasars, especially the radio quasars with large redshifts are clearly associated with bright galaxies.

The redshift distribution of quasar absorption lines and its origin

Abstract We have made statistical analyses of current data on the absorption line redshifts of quasars. All our results, including the distribution of relative velocities and the power-spectrum of the redshift distribution of absorption systems, are in favour of the cosmological hypothesis of the origin of the quasar absorption lines. We point out that the peaks in the relative velocity distribution are no compelling evidence for the rival, intrinsic hypothesis because they can be well explained by the model of density perturbation in the early universe [10].