On an explanation of the discretization of the redshifts of quasars

We show that the relation ln(1+z)=0.206 proposed to describe the discretization of the spatial distribution of quasars is a consequence of observational selection and is predetermined by the choice of the photometric system (U, B, V, R), the ratios of the wavelengths of the emission lines of Mg II, C III, C IV, Ly and the absorption lines O VI (1035 å) of the quasars studied.Translated fromAstrofizika, Vol. 37, No. 4, 1994.In conclusion I express gratitude to L. V. Mirzoyan for constant interest and moral support in the course of the present work and to G. A. Arutyunyan for valuable advice.     

A new strategy for estimating photometric redshifts of quasars

Based on the SDSS and SDSS-WISE quasar datasets, we put forward two schemes to estimate the photometric redshifts of quasars. Our schemes are based on the idea that the samples are firstly classified into subsamples by a classifier and then a photometric redshift estimation of different subsamples is performed by a regressor. Random Forest is adopted as the core algorithm of the classifiers, while Random Forest and k NN are applied as the key algorithms of regressors. The samples are divided into two subsamples and four subsamples, depending on the redshift distribution. The performances based on different samples, different algorithms and different schemes are compared. The experimental results indicate that the accuracy of photometric redshift estimation for the two schemes generally improves to some extent compared to the original scheme in terms of the percents in (|?z|)/(1+zi) 0.1 and (|?z|)/(1+zi) 0.2 and mean absolute error. Only given the running speed, k NN shows its superiority to Random Forest. The performance of Random Forest is a little better than or comparable to that of k NN with the two datasets. The accuracy based on the SDSS-WISE sample outperforms that based on the SDSS sample no matter by k NN or by Random Rorest. More information from more bands is considered and helpful to improve the accuracy of photometric redshift estimation. Evidently, it can be found that our strategy to estimate photometric redshift is applicable and may be applied to other datasets or other kinds of objects. Only talking about the percent in (|?z|)/(1+zi) 0.3, there is still large room for further improvement in the photometric redshift estimation.     

Alternative explanation for the spectral lines observed in quasars

It is shown that the emission lines observed in quasars can be satisfactorily explained as being due to laser action in certain atomic species in the expanding envelope of a star. There is no need to assume a redshift.     

Dependence of the U-B and B-V colors of quasars and Seyfert galaxies on their redshifts

We show that the strong emission lines(Mg II, C III, C IV, and Ly and the absorption lineO VI (1035 A) of quasars, when passed through the maximum transmission ofU, B, V, andR light filters, leads to a continuous, and sometimes periodic variation in the dependence ofU-B onB-V. The correlation between the(U-B) and(B-V) colors in quasars with z<1.5 is expressed by the relation(U-B)=–0.92+1.15(B-V). We also give the dependence ofU-B onB-V for Seyfert galaxies of typeS1. We determine the mean variation of the(U-B, B-V) colors due to the strongest emission lines (Mg II, C IV, Ly). It amounts to magnitude0 _. ^m 15.Translated fromAstrofizika, Vol. 38, No. 2, 1995.     

Gravitational and doppler redshifts of quasars interpreted as massive black holes ejected from galaxies

This is a first attempt to find a realistic explanation of the observed redshifts of quasars associated with galaxies, by considering, in addition to the inertial, also the gravitational time dilation in the strong field of quasars interpreted as huge black holes accreting matter from their surroundings. This interpretation allows us to understand the observed predominance of excess redshifts of quasars and construct possible semiquantitative models for the pair NGC 4319/Markarian 205. The proposed models do not contradict to the present astrophysical knowledge, but a selection of the most satisfactory one is still difficult because of the existing uncertainty in estimates of the sizes of radiating regions in matter accreted by a flying black hole.Essay received 2 March, 1979 by the Gravity Research Foundation (Gloucester, Mass., U.S.A.) and selected for Honorable Mention for 1979.     

Absorption line redshifts of QSOs in relation to their emission line redshifts

Analysis of the recent data indicate that absorption line redshifts of QSOs are significantly correlated to their emission line redshifts. It is concluded that the absorption lines originate in materials intrinsic to the QSOs.     

On the alignment of quasars

Taking the two Savage-Bolton 5° × 5° regions of optical quasar patrol as samples, I made a systematic analysis of the number of aligned quasars and compared with the random data generated by Monte Carlo method. The statistical result is that, at least for these two samples, there is no clear evidence for alignment.     

An explanation of the dimensions of penumbral filaments

Unstable pertubation modes exist in the magnetic field of penumbral electric current and I think the penumbral filaments are formed from the development of such modes. Under the short wave approximation the non-adiabatic dispersion equation is solved in the radial and transverse directions of the sunspot. From the condition of instability the length and width of the penumbral filament can be evaluated and it is found that the filament mode is static in the direction of the length and is non-moving in the direction of the width, that the penumbral filaments are a feature of the sunspot magnetic flow under gravity and that the presence of the filaments implies the existence of a twisted magnetic field.     

An explanation for the solar neutrino problem

A new mechanism of thermonuclear reaction is briefly introduced. It shows that a certain amount of thermonuclear reaction can take place in dense, low-temperature (T < 1 × 10⁵ K) plasmas. At a super-high temperature, it is in agreement with the old thermonuclear reaction mechanism first presented by Gamow and Bethe. As most regions in the Sun are at moderate and low temperature, a sufficient amount of fusion energy is generated therein. Therefore the solar central temperature in standard models must be decreased to about 13.8 × 10⁶ K. That would make the flux of high-energy neutrinos conform with the observational results.     

Anomalous redshifts and the variable mass hypothesis

There are several observations of extragalactic objects that do not appear to be consistent with the cosmological hypothesis that their redshifts arise from the expansion of the universe. These phenomena are looked at in a spacetime framework that is wider in its scope than general relativity. This framework directly incorporates the Machian notion of intertia and is conformally invariant. The consequence of this approach is that the mass of a particle may not stay constant. Two alternative viewpoints are presented to explain how large redshifts could arise from emission of radiation by particles of low masses.     

Distribution of quasars on the sky

It is shown that high-redshift quasars of bright apparent magnitude are concentrated in the direction of the centre of the Local Group of galaxies. A number of them are distributed along a line originating from the Local Group companion galaxy, M 33. A similar, but shorter and fainter line of quasars is seen emanating from the spiral galaxy NGC 300 in the next nearest, Sculptor Group of galaxies. The concentration of bright quasars in the Local Group direction is supported by bright radio sources catalogued in high-frequency surveys. One of the consequences of this large-scale inhomogeneity is to explain the different gradient of radio source counts in the direction of the Local Supercluster, a result discovered in 1978 but never investigated further. Previously reported homogeneity and isotropy of radio-source counts over the sky would seem to be an effect of integrating nearby, large-scale groupings with more distant, smaller-scale groupings over different directions in the sky. More careful analyses as a function of flux strength and spectral index on various scales over the sky are now required. Previous conclusions about radio source and quasar luminosity and number evolution drawn from logN- logS counts would then need to be re-evaluated.     

Clustering of galaxies at high redshifts

Recent observations show a large concentration of galaxies at high redshift. At first sight, strong clustering of galaxies at high redshifts seems to be in contradiction with the models of structure formation. In this paper we show that such structures are a manifestation of the strong clustering of rare peaks in the density field. We compute the frequency of occurrence of such large concentrations of galaxies in some models of structure formation.     

Luminosity evolution of quasars

Based on four previous studies with standard-candle quasars and using the correct formula for the luminosity distance, we obtain an improved determination of the deceleration parameter, q₀ = +2.07. From the new catalog of quasars, we find the statistical $\text{m}\text{?}\text{(z) - z}$ relation and hence the mean quasar luminosity $\text{M}\text{?}\text{(z)}$ or $\text{M}\text{?}\text{(t)}$ and its rates of change $\text{d}\text{M}\text{?}\text{(z)}\text{dz}$ and $\text{d}\text{M}\text{?}\text{(t)}\text{dt}$. Finally, we discuss the question whether there is a Malmquist effect in our sample and the question of the dichotomy of published q₀-values.     

Disparate MG II absorption statistics towards quasars and gamma-ray bursts: a possible explanation

We examine the recent report by Prochter et al. that gamma-ray burst (GRB) sight lines have a much higher incidence of strong Mg II absorption than quasar sight lines. We propose that the discrepancy is due to the different beam sizes of GRBs and quasars, and that the intervening Mg II systems are clumpy with the dense part of each cloudlet of a similar size as the quasars, i.e. ≲10¹⁶ cm, but bigger than GRBs. We also discuss observational predictions of our proposed model. Most notably, in some cases the intervening Mg II absorbers in GRB spectra should be seen varying, and quasars with smaller sizes should show an increased rate of strong Mg II absorbers. In fact, our prediction of variable Mg II lines in the GRB spectra has been now confirmed by Hao et al., who observed intervening Fe II and Mg II lines at z=1.48 to be strongly variable in the multi-epoch spectra of z=4.05 GRB 060206.     

An exploratory study of the hard X-ray variability properties of PG quasars with RXTE

We have monitored with the RXTE PCA the variability pattern of the 2–20 keV flux in four PG quasars (QSOs) from the Laor et al. (1994) sample. Six observations of each target at regular intervals of 1 day were performed. The sample comprises objects with extreme values of Balmer line width (and hence soft X-ray steepness) and spans about one order of magnitude in luminosity. The most robust result is that the variability amplitude decreases as energy increases. Several options for a possible ultimate driver of the soft and hard X-ray variability, such as the influx rate of Comptonizing relativistic particles, instabilities in the accretion flow or the number of X-ray ‘active sites’, are consistent with our results.     

The distribution of galaxy pair redshifts

High signal to noise neutral hydrogen observations of a complete sample of 132 galaxy pairs show a velocity difference distribution which decreases monotonically from zero. There is no strong indication of redshift periodicity for the entire sample and no indication at all for a subset of 79isolated galaxy pairs. In addition, when redshifts are corrected for the solar motion around the Galactic Center there is no indication of a redshift periodicity of 37.6 km s^–1 in V for galaxy pairs (as suggested by Guthrie and Napier 1996).