Magnetic field energy as a source of the radio luminosity of quasars

Energy release in the superconducting core of a neutron star as neutron vortices move toward the boundary of the star’s core and crust is examined. It is shown that the rate of energy release is on the order of 10²⁶-10³⁰ erg/s, or sufficient to provide the radio luminosity of known pulsars. The energy release rates calculated under the assumption of asymmetric energy release are compared with observational data on the radio luminosity of 575 pulsars.     

Optical variability properties of high luminosity AGN classes

We present the results of a comparative study of the intranight optical variability (INOV) characteristics of radio-loud and radioquiet quasars, which involves a systematic intra-night optical monitoring of seven sets of high luminosity AGNs covering the redshift rangez ≃ 0.2 toz ≃ 2.2. The sample, matched in the optical luminosity—redshift(M ^B—z) plane, consists of seven radio-quiet quasars (RQQs), eight radio lobedominated quasars (LDQs), five radio core-dominated quasars (CDQs) and six BL Lac objects (BLs). Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to detect INOV with amplitudes as low as about 1%. Present observations cover a total of 113 nights (720 hours) with only a single quasar monitored as continuously as possible on a given night. Considering the cases of only unambiguous detections of INOV we have estimated duty cycles (DCs) of 17%, 12%, 20% and 61% for RQQs, LDQs, CDQs, and BLs, respectively. The much lower amplitude and DC of ESfOV shown by RQQs compared to BLs may be understood in terms of their having optical synchrotron jets which are modestly misdirected from us. From our fairly extensive dataset, no general trend of a correlation between the INOV amplitude and the apparent optical brightness of the quasar is noticed. This suggests that the physical mechanisms of INOV and long term optical variability (LTOV) do not have a one-to-one relationship and different factors are involved. Also, the absence of a clear negative correlation between the INOV and LTOV characteristics of blazars of our sample points toward an inconspicuous contribution of accretion disk fluctuations to the observed INOV. The INOV duty cycle of the AGNs observed in this program suggests that INOV is associated predominantly with the highly polarized optical emission components. We also report new VLA imaging of two RQQs (1029 + 329 & 1252 + 020) in our sample which has yielded a 5 GHz detection in one of them (1252 + 020;S _5GHZ ≃ 1 mJy).     

Posterior probability of the deceleration parameter q0 from quasars provided with a luminosity indicator

We have worked out a ’statistical algorithm’ for obtaining the posterior probability density of the deceleration parameter q₀ from quasars where there is a luminosity indicator available. We point out that the role of the luminosity indicator is to provide asecond estimate of individual luminosities after a first estimate has been obtained from measured brightness and redshift together with an assumed q₀. Discrimination of q₀ is to be sought in the statistical properties of the set of differences between the two estimates (the residuals). We show that the variance of the residuals and their correlation with redshifts (further refined to luminosity distances) are two independent test-statistics for q₀, whose known distributions then lead to the probability density sought. We have applied the above algorithm to a sample of flat-spectrum radio quasars with measured CIV, MgII and Ly α lines. A combined Baldwin’s relation was used for all 3 lines. Our result is that log q₀ is normally distributed with a mean value of + 0.270± 0.135 (s.d.), or, q₀ = + 1.86 ± 0.135 dex. This result, we believe, is the sharpest result so far published on q₀.     

Two dynamical classes of Centaurs

The Centaurs are a transient population of small bodies in the outer Solar System whose orbits are strongly chaotic. These objects typically suffer significant changes of orbital parameters on timescales of a few thousand years, and their orbital evolution exhibits two types of behaviors described qualitatively as random walk and resonance-sticking. We have analyzed the chaotic behavior of the known Centaurs. Our analysis has revealed that the two types of chaotic evolution are quantitatively distinguishable: (1) the random walk type behavior is well described by so-called generalized diffusion in which the rms deviation of the semimajor axis grows with time t as ∼t^H, with Hurst exponent H in the range 0.22-0.95, however (2) orbital evolution dominated by intermittent resonance sticking, with sudden jumps from one mean motion resonance to another, has poorly defined H. We further find that these two types of behavior are correlated with Centaur dynamical lifetime: most Centaurs whose dynamical lifetime is less than ∼22 Myr exhibit generalized diffusion, whereas most Centaurs of longer dynamical lifetimes exhibit intermittent resonance sticking. We also find that Centaurs in the diffusing class are likely to evolve into Jupiter-family comets during their dynamical lifetimes, while those in the resonance-hopping class do not.     

Investigation of the correlation between morphology and luminosity for two classes of main galaxies

Using an apparent-magnitude limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 7(SDSS DR7), we investigate the correlation between morphologies and luminosity for the Main galaxy sample. Our Main galaxy sample is divided into two classes: Main galaxies only with TARGET_GALAXY flag (bestPrimtarget = 64), and ones also with other flags. It is found that for the second class Main galaxies, the early-type proportion monotonously increases with increasing luminosity nearly in the whole luminosity region. But for the first class Main galaxies, the early-type proportion increases with increasing luminosity only within a certain luminosity region (−22.2 < M _r  < −19.8). In the high luminosity region (M _r  < −22.2), the early-type proportion of the first class Main galaxies even decreases dramatically with increasing luminosity. We also analyze the correlation between morphologies and luminosity of galaxies around the peak of the redshift distribution ( 0.07 ≤ z ≤ 0.08 ). In such a narrow redshift region, we still observe strong correlation between morphologies and luminosity, which shows that this correlation is fundamental.     

Statistical relations between stellar spectral and luminosity classes and stellar effective temperature and surface gravity

We have determined new statistical relations to estimate the fundamental atmospheric parameters of effective temperature and surface gravity, using MK spectral classification, and vice versa. The relations were constructed based on the published calibration tables(for main sequence stars) and observational data from stellar spectral atlases(for giants and supergiants). These new relations were applied to field giants with known atmospheric parameters, and the results of the comparison of our estimations with available spectral classification have been quite satisfactory.     

Two classes of volcanic plumes on Io

Comparison of Voyager 1 and Voyager 2 images of the south polar region of Io has revealed that a major volcanic eruption occured there during the period between the two spacecraft encounters. An annular deposit ～1400 km in diameter formed around the Aten Patera caldera (311°W, 48°S), the floor of which changed from orange to red-black. The characteristics of this eruption are remarkably similar to those described earlier for an eruption centered on Surt caldera (338°W, 45°N) that occured during the same period, also at high latitude, but in the north. Both volcanic centers were evidently inactive during the Voyager 1 and 2 encounters but were active sometime between the two. The geometric and colorimetric characteristics, as well as scale of the two annular deposits, are virtually identical; both resemble the surface features formed by the eruption of Pele (255°W, 18°S). These three very large plume eruptions suggest a class of eruption distinct from that of six smaller plumes observed to be continously active by both Voyagers 1 and 2. The smaller plumes, of which Prometheus is the type example, are longer-lived, deposit bright, whitish material, erupt at velocities of ～0.5 km sec^?1, and are concentrated at low latitudes in an equatorial belt around the satellite. The very large Pele-type plumes, on the other hand, are relatively short-lived, deposit darker red materials, erupt at ～1.0 km sec^?1, and (rather than restricted to a latitudinal band) are restricted in longitude from 240° to 360°W. Both direct thermal infrared temperature measurements and the implied color temperatures for quenched liquid sulfur suggest that hot spot temperatures of ～650°K are associated with the large plumes and temperatures <400°K with the small plumes. The typical eruption duration of the small plumes is at least several years; that of the large plumes appears to be of the order of days to weeks. The two classes therefore differ by more than two orders of magnitude in duration of eruption. Based on uv, visible, and infrared spectra, the small plumes seem to contain and deposit SO₂ in their annuli whereas the large plumes apparently do not. Two other plumes that occur at either end of the linear feature Loki may be intermediate or hybrid between the two classes, exhibiting attributes of both. Additionally, Loki occurs in the area of overlap in the regional distributions of the two plume classes. Two distinct volcanic systems involving different volatiles may be responsible for the two classes. We propose that the discrete temperatures associated with the two classes are a direct reflection of sulfur's peculiar variation in viscosity with temperature. Over two temperature ranges (～400 to 430°K and >650°K), sulfur is a low-viscosity fluid (orange and black, respectively); at other temperatures it is either solid or has a high viscosity. As a result, there will be two zones in Io's crust in which liquid sulfur will flow freely: a shallow zone of orange sulfur and a deeper zone of black sulfur. A low-temperature system driven by SO₂ heated to 400 to 400°K by the orange sulfur zone seems the best model for the small plumes; a system driven by sulfur heated to >650°K by hot or even molten silicates in the black sulfur zone seems the best explanation for the large plume class. The large Pele-type plumes are apparently concentrated in a region of the satellite in which a thinner sulfur-rich crust overlies the tidally heated silicate lithosphere, so the black sulfur zone may be fairly shallow in this region. The Prometheus-type plumes are possibly confined to the equatorial belt by some process that concentrates SO₂ fluid in the equatorial crust.     

The optical luminosity evolution function of quasars. I. A statistical evolution function that includes the large redshift range above redshift 2.2

We have redetermined the parameters in the Heisler-Ostriker quasar evolution formula so as to make it applicable to a larger redshift range. The form of the formula is appropriate because, physically, any variation in the mass of the central black hole and the accretion rate will cause a luminosity evolution while the birth of quasars will imply a luminosity-dependent density evolution. With our new parameters, we can 1) reproduce the quasar magnitude count down to magnitude 22.0, 2) reproduce the quasar redshift distribution in intervals of ΔZ = 0.1 and 3) substantially lessen the excess count for Z > 2 redicted by previous formulae.     

Properties of X-ray quasars

A statistical analysis of the X-ray properties of 247 quasars observed by the Einstein Observatory in the 0.5–4.5 kev band is made. The main results are as follows. Among the various magnitude and redshift groups of 1619 known quasars, the proportion of X-ray sources is nearly constant. There is a strong correlation between the X-luminosity of Type-I Seyferts and the ratio of the equivalent widths of their Hg and [OIII] emission lines; the latter can be used as a X-luminosity indicator. The X-luminosity is correlated with both the optical luminosity and the radio luminosity above 2.5 GHz, suggesting that they have a similar emission mechanism and the regions of their emission are in that order. The X-luminosity is not correlated with either U-B or B-V. There is a weak correlation between the two colour indices.     

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.     

Absorption spectra of quasars

A. F. Ioffe Physicotechnical Institute, USSR Academy of Sciences. Translated from Astrofizika, Vol. 29, No. 2, pp. 408–430, September–October, 1988.     

Redshift-magnitude relations for quasars

Two cosmological models represent the observed magnitudes and redshifts of 150 quasars well with 〈Mv〉=?22.75 and ?22.67, respectively. The luminosity function is derived.     

A structure for quasars

We propose a simple unifying structure for the inner regions of quasars and AGN. This empirically derived model links together the BALs, the narrow UV/X-ray ionized absorbers, the BELR, and the Compton scattering/fluorescing regions into a single structure. The model also suggests an origin for the large-scale bi-conical outflows. Some other potential implications of this structure are discussed.