Dependence of Fanaroff–Riley break of radio galaxies on luminosity and redshift

We investigate the dependence of the Fanaroff–Riley (FR) 1/2 dichotomy of radio galaxies on their luminosities and redshifts. Because of a very strong redshift-luminosity correlation (Malmquist bias) in a flux-limited sample, any redshift-dependent effect could appear as a luminosity-related effect and vice versa. A question could then arise—do all the morphological differences seen in the two classes (FR 1 and 2 types) of sources, usually attributed to the differences in their luminosities, could as well be primarily a redshift-dependent effect? A sharp break in luminosity, seen among the two classes, could after all reflect a sharp redshift dependence due to a rather critical ambient density value at some cosmic epoch. A doubt on these lines does not seem to have been raised in past and things have never been examined with this particular aspect in mind. We want to ascertain the customary prevalent view in the literature that the systematic differences in the two broad morphology types of FR 1 and 2 radio galaxies are indeed due to the differences in their luminosities, and not due to a change in redshift. Here we investigate the dependence of FR 1/2 dichotomy of radio galaxies on luminosity and redshift by using the 3CR sample, where the FR 1/2 dichotomy was first seen, supplemented by data from an additional sample (MRC), that goes about a factor of 5 or more deeper in flux-density than the original 3CR sample. This lets us compare sources with similar luminosities but at different redshifts as well as examine sources at similar redshifts but with different luminosities, thereby allowing us a successful separation of the otherwise two intricately entangled effects. We find that the morphology type is not directly related to redshift and the break between the two types of morphologies seems to depend only upon the radio luminosity.     

The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources(Ⅲ)

Active galactic nuclei(AGNs) can be divided into two major classes,namely radio-loud and radio-quiet AGNs.A small subset of the radio-loud AGNs is called blazars,which are believed to be unified with Fanaroff-Riley type Ⅰ and type Ⅱ(FRIⅡ) radio galaxies.Following our previous work,we present a latest sample of 966 sources with measured radio flux densities of the core and extended components.The sample includes 83 BL Lacs,473 flat spectrum radio quasars,101 Seyferts,245 galaxies,52 FRIsⅡs and12 unidentified sources.We then calculate the radio core-dominance parameters and spectral indices and study their relationship.Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources.We also confirm that the correlation between core-dominance parameter and radio spectral index extends over all the sources in a large sample presented.     

The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources(Ⅱ)

Active galactic nuclei(AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type Ⅰ/Ⅱ(FRI/Ⅱ) radio galaxies. Following our previous work(Fan et al.), we present a sample of 2400 sources with measured radio flux densities of the core and extended components. The sample contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRⅡ galaxies and 104 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices, and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and spectral index exists for a large sample presented in this work.     

Ambartsumian’s paradigm for the activity of galactic nuclei and the evolution of galaxies

Ambartsumian’s paradigm for the creation of galaxies owing to the decay of denser matter is examined. The roots of this concept can be found in the very earliest papers of Ambartsumian on quantum fields and the structure of atomic nuclei. In the early 1930’s his papers contained new ideas regarding the ejection by one physical object of another which had not originally existed inside the first. The basic observational data which served as the basis for the final formulation of the new concept are described. Special attention is devoted to those objects and phenomena, which, upon further study, have confirmed the validity of Ambartsumian’s reasoning and arguments. It is noted that the discovery of Hubble expansion’s acceleration of the universe opened up new possibilities for the interpretation of activity phenomena in terms of Ambartsumian’s concept. The further extension of this concept is discussed and it is suggested that the major result of this approach should be the proof of the existence of galaxies of all ages within a finite volume of space.     

The formation of hot subdwarf stars and its implications for the UV-upturn phenomenon of elliptical galaxies

In this paper, we review the formation scenario for field hot subdwarf stars and extreme horizontal branch stars in globular clusters and discuss how the scenario helps us to understand the UV-upturn phenomenon of elliptical galaxies. It is widely accepted that field hot subdwarf stars originate from binary evolution via the following three channels, common envelope evolution channel for hot subdwarf binaries with short orbital periods, stable Roche lobe overflow channel for hot subdwarf binaries with long orbital periods, and the double helium white dwarf merger channel for single hot subdwarfs. Such a scenario can also explain the lack of binarity of extreme horizontal branch stars in globular clusters. We have applied, in an a priori way, the scenario to the study of UV-upturn phenomenon of elliptical galaxies via an evolutionary population synthesis approach and found that the UV-upturn can be naturally explained. This has major implications for understanding the evolution of UV-upturn and elliptical galaxies in general. In particular, it implies that the UV-upturn is not a sign of age, as had been postulated previously, and should not be strongly dependent on the metallicity of the population, but exists universally from dwarf ellipticals to giant ellipticals. The above a priori UV-upturn model is supported by recent GALEX observations and has been applied to naturally explain the colours of both dwarf ellipticals and giant ellipticals without the requirement of dichotomy between their stellar population properties.     

Similarity of jet radiation between flat spectrum radio quasars and GeV narrow-line Seyfert 1 galaxies: a universal δ-L_c correlation

By modeling the broadband spectral energy distributions(SEDs) of a typical flat spectrum radio quasar(FSRQ, 3C 279) and two GeV narrow-line Seyfert 1 galaxies(NLS1s, PMN J0948+0022 and 1H0323+342) in different flux stages with one-zone leptonic models, we find a universal correlation between their Doppler factors(δ) and peak luminosities(L_c) of external Compton scattering bumps. Compiling a combined sample of FSRQs and GeV NLS1s, it is found that both FSRQs and GeV NLS1s in different stages and in different sources follow the same δ-L_c correlation well. This indicates that the variations of observed luminosities may be essentially due to the Doppler boosting effect. The universal δ-L_c relation between FSRQs and GeV NLS1s in different stages may be further evidence that the particle acceleration and radiation mechanisms for the two kinds of sources are similar. In addition, by replacing L_c with the observed luminosity in the Fermi/LAT band(L_(LAT)), this correlation holds and it may serve as an empirical indicator of δ. We estimate the δ values with L_(LAT) for 484 FSRQs in the Fermi/LAT Catalog and they range from 3 to 41, with a median of 16, which are statistically consistent with the values derived by other methods.     

The Ks-band Tully-Fisher Relation — A determination of the Hubble parameter from 218 ScI galaxies and 16 galaxy clusters

The value of Hubble parameter (H₀) is determined using the morphologically type dependent Ks-band Tully-Fisher Relation (K-TFR). The slope and zero point are determined using 36 calibrator galaxies with ScI morphology. Calibration distances are adopted from direct Cepheid distances, and group or companion distances derived with the Surface Brightness Fluctuation Method or Type Ia Supernova. It is found that a small morphological type effect is present in the K-TFR such that ScI galaxies are more luminous at a given rotational velocity than Sa/Sb galaxies and Sbc/Sc galaxies of later luminosity classes. Distances are determined to 16 galaxy clusters and 218 ScI galaxies with minimum distances of 40.0 Mpc. From the 16 galaxy clusters a weighted mean Hubble parameter of H₀ = 84.2 ± 6 km s⁻¹ Mpc⁻¹ is found. From the 218 ScI galaxies a Hubble parameter of H₀ = 83.4 ± 8 km s⁻¹ Mpc⁻¹ is found. When the zero point of K-TFR is corrected to account for recent results that find a Large Magellanic Cloud distance modulus of 18.39±0.05, a Hubble parameter of 88.0 ± 6 km s⁻¹ Mpc⁻¹ is found. Effects from Malmquist bias are shown to be negligible in this sample as galaxies are restricted to a minimum rotational velocity of 150 km s⁻¹. It is also shown that the results of this study are negligibly affected by the adopted slope for the K-TFR, inclination binning, and distance binning. A comparison with the results of the Hubble Key Project (Freedman et al. 2001) is made. Discrepancies between the K-TFR distances and the HKP I-TFR distances are discussed. Implications for Λ-CDM cosmology are considered with H₀ = 84 km s⁻¹ Mpc⁻¹. It is concluded that it is very difficult to reconcile the value of H0 found in this study with ages of the oldest globular clusters and matter density of the universe derived from galaxy clusters in the context of Λ-CDM cosmology.     

The maximum limit of the density variation parameter λ for a stable neutron star

A static spherically-symmetric model, based on an exact solution of Einstein's equation, gives the permissible matter density 2×10¹⁴ g cm^–3. If we use the change in the ratio of central density to the radiusr=a (i.e., central density per unit radius (₀/a), we call it radius density) minimum, we have estimated the upper limit of the density variation parameter () and minimum mass limit of a superdense star like a neutron star. This limit gives an idea of the domain where the neutron abundance with negligible number of electrons and protons (may be treated as pure neutrons) and equilibrium in neutrons begins.     

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

From the characteristic actions ^(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 actions ^(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 valueH ₀ 50 km s^–1 Mpc^–1, the protogalaxies might be formed just before recombination.     

The Voigt profile of the decameter radio recombination lines and electron density of the expanding CII region towards Cassiopeia A

The carbon decameter radio recombination line (RRL) shape is described by a Voigt profile, since explicit line broadening is observed in the wings. A Lorentz component line half width is determined by the method of a Lorentz and Gauss line profile fitting of a curve. Since the Lorentz line shape is described by the Stark effect and the interaction with the Galaxy non-thermal background radiation, then by comparing the Lorentz component experimental and theoretical values a medium component electron density can be calculated for an expanding CII region towards Cassiopeia A. So far as the decameter lines are formed due to the transitions between the levels with large principal quantum numbers n>600, the life time, and thus the line width are very large. The collision transition rate is described by the perturbation theory for a low temperature medium. The radius matrix elements for a highly excited atom are defined more exactly with determining the transition rates for radiation interaction and scattering.     

Possible γ-ray emission of radio intermediate AGN Ⅲ Zw 2 and its implication on the evolution of jets in AGNs

AGNs with hard γ-ray emission identified so far are radio-loud.III Zw 2 is a radio intermediate AGN with a relativistic jet.We study its spectral energy distribution (SED) and find that the broad band emissions are dominated by the non-thermal emissions from the jet.We model its SED through a synchrotron + inverse Compton (IC) model.The results show that the IC component of III Zw 2 peaks at a few MeV, and the flux density drops rapidly at higher energy with photon index Γ≈3.3 above 0.1GeV.The predicted flu...     

The effect of mass-loss and semiconvection on the evolution of a 15M ⊙ population I star

Evolutionary sequences are computed from the main sequence to central helium exhaustion for a 15M star, with an initial composition ofX=0.70,Y=0.27,Z=0.03. Parallel sequences are computed to investigate the effects of different mass loss rates on the evolution of the star. These rates are chosen to reflect the physical causes of the mass loss, and occur at all phases of evolution. One sequence without, and one with, mass loss are recomputed, allowing for semiconvection and full convection in intermediate mass zones, using the Schwarzschild and Härm criterion for convective neutrality.Low to moderate rates of mass loss in the early evolutionary phases shift the evolution to lower luminosities and effective temperatures, but do not radically alter the form of evolution. However, the resulting evolutionary sequences can be up to 25% undermassive for their luminosity as they enter the red giant branch (RGB). Most sequences evolve through a subsequent stable blue phase (the blue loop), which is shifted to lower luminosities and effective temperatures by the previous mass loss and is also widened. This blue loop is suppressed if approximately 10% of the stellar mass is lost in the RGB. Mass loss delays the evolution of the central region of the star relative to that of the outer region, so that central helium ignition and exhaustion are displaced to later points on the evolutionary tracks. Mass loss also reduces the size of the helium core, although its mass fraction is larger.If semiconvective and intermediate fully convective zones are included, then in a sequence without mass loss these zones greatly alter the chemical profile of the model. The sequence evolves at a higher luminosity, with a stable blue supergiant phase occurring prior to the RGB. Central helium exhaustion occurs during the ascent of the RGB. However, if mass loss is included, the extent of these zones is drastically reduced, and the evolutionary pattern is similar to that without such zones. No blue loop is found.Observations indicate that the blue supergiant region is wider and bluer than predicted by previous evolutionary calculations. The present results show that mass loss widens and reddens this phase. Hence, the inclusion of other factors will be necessary to reconcile theory and observations.     

The circumstellar matter of type Ⅱ intermediate luminosity optical transients(ILOTs)

I find that a ■ outflowing equatorial dusty disk (torus) that the binary system progenitor of an intermediate luminosity optical transient (ILOT) ejects several years to several months before and during the outburst can reduce the total emission to an equatorial observer by two orders of magnitude and shifts the emission to wavelengths of mainly λ■10μm.This is termed a type Ⅱ ILOT(ILOT Ⅱ).To reach this conclusion,I use calculations of type Ⅱ active galactic nuclei and apply them to the equatorial ejecta (disk/torus) of ILOTs Ⅱ.This reduction in emission can last for tens of years after outburst.Most of the radiation escapes along the polar directions.The attenuation of the emission for wavelengths ofλ5μm can be more than three orders of magnitude,and the emission at λ■2μm is negligible.Jets that the binary system launches during the outburst can collide with polar CSM and emit radiation above the equatorial plane and dust in the polar outflow can reflect emission from the central source.Therefore,during the event itself the equatorial observer might detect an ILOT.I strengthen the previously suggested ILOT Ⅱ scenario to the event N6946-BH1,where a red giant star disappeared in the visible.     

The equivalent width of the Hβ emission line and the evolution of the Hii regions

The synthetic equivalent width (W _H) of the line H in emission is obtained for Hii regions opaque to the Lyman photon flux, with embedded OB associations with different initial chemical compositions and initial mass functions. The variation ofW _H as a function of the evolution of the ionizing stars is analysed. The observations ofW _H for M33, M101, and M51 by Searle (1971) are discussed.     

The influence of magnetic fields on the Sunyaev–Zel’dovich effect in clusters of galaxies

We study the influence of intracluster large scale magnetic fields on the thermal Sunyaev–Zel’dovich (SZ) effect. In a macroscopic approach we complete the hydrostatic equilibrium equation with the magnetic field pressure component. Comparing the resulting mass distribution with a standard one, we derive a new electron density profile. For a spherically symmetric cluster model, this new profile can be written as the product of a standard (β-) profile and a radius dependent function, close to unity, which takes into account the magnetic field strength. For non-cooling flow clusters we find that the observed magnetic field values can reduce the SZ signal by ∼10% with respect to the value estimated from X-ray observations and the β-model. If a cluster harbours a cooling flow, magnetic fields tend to weaken the cooling flow influence on the SZ-effect.     

The impact of Earth’s shadow on the long-term evolution of space debris

Direct solar radiation pressure and Earth’s shadow crossings are known to be responsible for short-term variations of space debris orbital elements, the higher the area-to-mass ratio the larger the perturbation. Nevertheless, existing studies have always been performed on periods of time shorter than 150 years. Considering longer time scales of the order of a 1000 years, this paper focuses on the long-term periodic evolution of space debris trajectories caused by successive Earth’s shadow crossings. Other perturbations as the geopotential and third-body gravitational attractions obviously play a role and compete with the one which is described in this paper. Symplectic numerical propagations and new (semi-)analytical models are developed to identify a frequency associated to shadow entry and exit eccentric anomalies. It is shown that Earth’s shadow is responsible for large deviations from the initial orbital elements, even on shorter period of times, and that this effect increases along with the area-to-mass ratio.     

Theory of gravitational radiation of the (Ω,A µν )-field

Further exploration of the -field theory as first proposed by Yu (1989) is here presented to cover the equation of motion of a test particle which induces gravitational radiation. The same theory is shown to contain an exact gravitational radiation equation derived as a logical consequence of field equations without extra postulates. In this general dynamic context the theory is renamed The (,A _µ )-field Theory.     

The mass,orbit, and tidal evolution of the Quaoar–Weywot system

Here we present new adaptive optics observations of the Quaoar–Weywot system. With these new observations we determine an improved system orbit. Due to a 0.39 day alias that exists in available observations, four possible orbital solutions are available with periods of ～11.6, ～12.0, ～12.4, and ～12.8 days. From the possible orbital solutions, system masses of 1.3–1.5 ± 0.1 × 10²¹ kg are found. These observations provide an updated density for Quaoar of 2.7–5.0 g cm^?3. In all cases, Weywot’s orbit is eccentric, with possible values ～0.13–0.16. We present a reanalysis of the tidal orbital evolution of the Quaoar–Weywot system. We have found that Weywot has probably evolved to a state of synchronous rotation, and has likely preserved its initial inclination over the age of the Solar System. We find that for plausible values of the effective tidal dissipation factor tides produce a very slow evolution of Weywot’s eccentricity and semi-major axis. Accordingly, it appears that Weywot’s eccentricity likely did not tidally evolve to its current value from an initially circular orbit. Rather, it seems that some other mechanism has raised its eccentricity post-formation, or Weywot formed with a non-negligible eccentricity.     

Radio loudness of high-redshift (z≥3) quasars from the Sloan Digital Sky Survey

Using a homogenous sample of 1962 quasars with redshift 3.0≤z≲4.5 drawn from the Sloan Digital Sky Survey (SDSS), we study the relationships between radio loudness, virial black hole (BH) mass and Eddington ratio (accretion rate relative to the Eddington limit). For the radio-detected objects, we find a significant (>99.5 per cent) anticorrelation between radio loudness R parameter and BH mass, consistent with previous studies of low-redshift radio-loud quasars. The truly radio-loud quasars (R>30) are found to be confined to M _BH≲10¹⁰ M_⊙ within our sample. We also find that R is only weakly correlated with Eddington ratio L _bol/L _Edd. Combined with previous results on the low-redshift R−L _bol/L _Edd relation, this result indicates no strong L _bol/L _Edd dependence of R at L _bol/L _Edd≳10⁻². On the other hand, the large scatter in these relationships suggests that other physical properties such as BH spin and quasar clustering must also play an important role in quasar radio emission.     

The LAMOST survey of background quasars in the vicinity of M31 and M33–Ⅲ.results from the 2013 regular survey

In this work, we report new quasars discovered in fields in the vicinity of the Andromeda(M31) and Triangulum(M33) galaxies with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST, also called the Guo Shou Jing Telescope) during the 2013 observational season, the second year of the regular survey. In total, 1330 new quasars are discovered in an area of ～133 deg2 around M31and M33. With i magnitudes ranging from 14.79 to 20.0 and redshifts from 0.08 to4.85, the 1330 new quasars represent a significant increase in the number of identified quasars in fields in the vicinity of M31 and M33. Up to now, there have been a total of 1870 quasars discovered by LAMOST in this area. The much enlarged sample of known quasars in this area can potentially be utilized to construct a precise astrometric reference frame for the measurement of minute proper motions of M31, M33 and their associated substructures, which are vital for understanding the formation and evolution of M31, M33 and the Local Group of galaxies. Moreover, in the sample,there are a total of 45, 98 and 225 quasars with i magnitudes brighter than 17.0, 17.5and 18.0 respectively. In the aforementioned brightness bins, 15, 35 and 84 quasars are reported here for the first time, and 6, 21 and 81 are reported in our pervious work. In addition, 0, 1 and 6 are from the Sloan Digital Sky Survey and 24, 41 and 54 are from the NED database. These bright quasars provide an invaluable sample to study the kinematics and chemistry of the interstellar/intergalactic medium of the Local Group.