On the light variations of Seyfert galaxy 3C120

The fragmentary light-curve of the Seyfert galaxy 3C120, based on photometry of the bestavailable Harvard plates of the past 60 yr, has been subjected to a periodicity analysis using a method (Appendix) particularly suited to this type of irregularly-spaced data. The analysis yields convincing evidence for a period of about 350 d and some indication of a longer period of about 22.5 yr. The observational data often depart appreciably from the light curve synthesized from the two periodic components. In one comparatively well-documented segment (1934–1939), the agreement between observational data and the synthesized model improves if it is assumed that a pair of oppositelydirected phase shifts have occurred, disturbing the 350-day period and then causing it to recover.     

Comparison of the X-ray and optical variabilities in the Seyfert galaxy 3C 120

Based on our UBV RI observations and X-ray data from the RXTE satellite, we have investigated the variability of the galaxy 3C 120 over the period 1996–2008. The relative variability amplitude in the U and B bands without any subtraction of the contribution from the underlying galaxy is 23 and 22%, respectively, against 21% in the X-ray band. The autocorrelation function based on the B-band data is considerably wider than that based on the X-ray data. The structure functions on a time scale from 1 to ～100–300 days in the X-ray and optical spectral ranges have the form of a power law (SF ～ τ ^b ). However, their indices differ significantly: b = 0.42 in the X-ray band and b = 1.36 in the B band. Considering the X-ray and optical variabilities as a superposition of independent flares in a wide range of durations, we may conclude that the amplitudes of short flares in the X-ray band are higher than those in the optical one and, conversely, the relative amplitudes of long flares in the X-ray band are slightly lower than those in the optical one, i.e., short events dominate in the X-ray band. The optical flux variations in the R _c and I _c bands lag significantly behind those in the B band, by 3.9 _?0.7 ^+1.0 and 6.2 _?0.6 ^+1.1 days, respectively, if the lag is estimated from the centroid of the cross-correlation function. The X-ray variability on a time scale of about 1800 days (～5 yr) lags behind the B-band variations by 5.3 _?3.3 ^+2.7 days, but the confidence level of this estimate is only 87%. A more detailed analysis of the correlation between the X-ray and optical emissions has revealed a fairly complex picture: different degrees of correlation between the optical and X-ray fluxes are observed at different times.     

Variations in the integral fluxes and structure of the radio source 3C120

The variability of the radio source 3C120 is studied using data from the international geodesic VLBI observation programs at 8.6 GHz and regular monitoring over frequencies of 4.8–36.8 GHz carried out at the Crimean Astrophysical Observatory (Ukraine) and the Radio Astronomy Observatory of the University of Michigan (USA). A combined analysis of the integral fluxes and structures on millisecond scales reveals the existence of flares at high frequencies accompanied by the appearance of new VLBI components at centimeter wavelengths. It is found that the variations in the fluxes for 3C120 at various radio frequencies have delayed maxima at low frequencies, and the flare of 1998 was accompanied by the birth of a new superluminal component. __________ Translated from Astrofizika, Vol. 50, No. 3, pp. 325–334 (August 2007).     

3C 120射电光变曲线中的一个可能周期

本文利用两种周期分析方法(Jurkevich方法和功率谱方法)分析了赛弗特星系3C120五个射电波段的光变曲线(4.8,8,14.5,22和37 GHz)。结果发现了一个大约为4.2a(年)的周期共同存在于5个波段的光变曲线中。这个周期可能能用双黑洞模型来解释。     

Electron capture of nuclei in the region surrounding magnetar

Effects of ultra-strong magnetic field on electron capture rates for ⁵⁷Fe, ⁵⁸Co and ⁵⁹Ni have been analyzed in the nuclear shell model and under the Landau energy levels quantized approximation in the ultra-strong magnetic field, the result increase about 3 orders magnitude. The rate of change of electron abundance, $\dot{Y}_{e}$ , for every nuclide and total $\dot{Y}_{e}$ in the condition without magnetic field and B=4.414×10¹⁵ G have been calculated, and exceed about 6 orders of magnitude generally. These conclusions play an important role in future studying the evolution of magnetar.     

Are 3C 120 and Other Active Galactic Nuclei Overweight Microquasars?

The appearance of superluminal radio knots follows drops in the X-ray flux in the FR1 radio galaxy 3C 120 and possibly the FR2 source 3C 111. This corresponds in a very general way to the behavior of the X-ray binary GRS 1915 + 105, but the light curves of the microquasar are much richer in detail. Starting in 2003.7, the character of the radio and X-ray light curves of 3C 120 changed, perhaps signaling a new stage of activity. I discuss here what one might expect when a microquasar is scaled up to AGN dimensions, and compare this with what we see in 3C 120. There is a mismatch between expectations and observations.     

Active region of the nucleus of the blazar 3C 454.3

The superfine structure of the object 3C 454.3 has been investigated at λ = 7 mm in polarized emission. The kinematics of the structure is shown to correspond to a vortex. A spiral structure like an Archimedes spiral has been established in the accretion disk. The orbital velocity of the inflow exceeds considerably the radial velocity. The disk is oriented in the plane of the sky. The bipolar outflow ejection axis is directed toward the observer with a slight inclination to the east. The jet sizes exceed considerably the counterjet sizes. The jet is ejected in a direction opposite to the observer; its apparent separation from the nozzle is determined by the disk shadowing. The counterjet is directed toward the observer; the flow brightness temperature at the exit from the nozzle reaches T _b ≈ 10¹⁵ K. The jet has a spiral shape with an increasing pitch; the counterjet is a mirror reflection of the initial part of the jet. The incoming thermal plasma is accelerated and heated to relativistic temperatures as it is transferred along a spiral to the center. The orientation of the emission polarization plane changes along the flows due to a change in the ratio of the orbital and radial velocities, a change in the magnetic field orientation.     

Kinematics of the active region of the quasar 3C 345

The fine structure of the quasar 3C 345 in polarized emission at 7 mm and 2 cm has been investigated. The kinematics is shown to correspond to an anticentrifuge: the thermal plasma of the surrounding space accretes onto the disk, flows to the center, and is ejected in the form of a rotating bipolar outflow that carries away the excess angular momentum as it accumulates. The bipolar outflow consists of a high-velocity central jet surrounded by a low-velocity component. The low-velocity flows are the rotating hollow tubes ejected from the peripheral part of the disk with a diameter ～Ø₁ = 2.2 pc and from the region Ø₂ = 1 pc. The high-velocity jet with a diameter Ø₃ = 0.2 pc is ejected from the central part of the disk, while the remnant falls onto the forming central body. The ejection velocity of the high-velocity flow is v ? 0.06c. At a distance up to ～1 pc, the jet accelerates to an apparent velocity v ～ 8c. Further out, uniform motion is observed within ～2 pc following which deceleration occurs. The jet structure corresponding to a conical diverging helix with an increasing pitch is determined by gasdynamic instability. The counterjet structure is a mirror reflection of the nearby part of the jet. The brightness temperature of the fragment of the high-velocity flow at the exit from the counterjet nozzle is T _b ≈ (10¹²?10¹³) K. The disk inclined at an angle of 60° to the plane of the sky shadows the jet ejector region. Ring currents observed in the tangential directions as parallel chains of components are excited in the rotating flows. The magnetic fields of the rotating bipolar outflow and the disk are aligned and oriented along the rotation axis. The translational motions of the jet and counterjet are parallel and antiparallel to the magnetic field, which determines their acceleration or deceleration. The quasar core is surrounded by a thermal plasma. The sizes of the HII region reach ～30 pc. The electron density decreases with increasing distance from the center from N _e ≈ 10⁸ to ≈10⁵ cm^?3. The observed emission from the jet fragments at the exit from the nozzle is partially absorbed by the thermal plasma, is refracted with increasing distance—moves with an apparent superluminal velocity, and decelerates as it goes outside the HII region.     

Properties of energetic water-group ions in the extended pick-up region surrounding comet Giacobini-Zinner

The properties of energetic (65–95 keV) cometary water-group ions in the extended solar wind pick-up region surrounding comet Giacobini-Zinner are examined using data from the EPAS instrument on the ICE spacecraft. In the outer part of this region, extending from cometocentric distances of several hundred thousand to a few million kilometres (the limit of pick-up ion detectability), it is found that large modulations of the ion flux occur (with J_MAX/J_MIN 10²-10³) which are related to the direction of the magnetic field. It is also found that the ions stream in a direction which is intermediate between the directions of the solar wind flow and the E × B drift, and that ions are present at energies somewhat above the local pick-up energy. These properties indicate that the waves which are excited by the unstable “ring-beam” pick-up ion velocity distributions do result in significant scattering of the ions in this region, both in pitch angle and in energy, but that they have insufficient amplitude to scatter the ions into near isotropy in the solar wind frame. Closer to the comet (but still upstream from the bow shock), the ion flux modulations are considerably reduced in amplitude and the ions respond less to the E × B drift, indicating that the ions are scattered nearer to isotropy in this region. Inbound, this transition takes place relatively abruptly at a distance of 4 × 10⁵ km in association with an increase in the solar wind speed, after which the ion flux increases, and ceases to be modulated by the field direction, while the streaming direction is continuously antisolar and unmodulated by the direction of the E × B drift. Outbound, weak vestiges of the ring-beam ion anisotropy are present in the region immediately upstream from the bow shock (at −1 × 10⁵ km), but these become more marked at distances in excess of t4 × 10⁵ km, increasing gradually with increasing distance from the comet. It is shown that the evolution of the ion properties is qualitatively consistent with expectations based on quasi-linear diffusion of the ions by the magnetosonic waves observed during the encounter.     

Analysis of the geomorphology surrounding the Chang'e-3 landing site

Chang'e-3(CE-3) landed on the Mare Imbrium basin in the east part of Sinus Iridum(19.51°W, 44.12°N), which was China's first soft landing on the Moon and it started collecting data on the lunar surface environment. To better understand the environment of this region, this paper utilizes the available high-resolution topography data, image data and geological data to carry out a detailed analysis and research on the area surrounding the landing site(Sinus Iridum and 45 km×70 km of the landing area)as well as on the topography, landform, geology and lunar dust of the area surrounding the landing site. A general topographic analysis of the surrounding area is based on a digital elevation model and digital elevation model data acquired by Chang'e-2 that have high resolution; the geology analysis is based on lunar geological data published by USGS; the study on topographic factors and distribution of craters and rocks in the surrounding area covering 4 km×4 km or even smaller is based on images from the CE-3 landing camera and images from the topographic camera; an analysis is done of the effect of the CE-3 engine plume on the lunar surface by comparing images before and after the landing using data from the landing camera. A comprehensive analysis of the results shows that the landing site and its surrounding area are identified as typical lunar mare with flat topography. They are suitable for maneuvers by the rover,and are rich in geological phenomena and scientific targets, making it an ideal site for exploration.     

Circumzenithal sky region survey at the frequency of 30 GHz with 32-element radiometer matrix of the RATAN-600

We report the preliminary results of a deep sky survey in the field of 00^h < RA < 24^h, 40 _. ^° 5 < 42 _. ^° 5 with the RATAN-600 and its new focal 32-feed receiver matrix at the limiting radio frequency of 30 GHz, with the resolution up to 5″ in right ascension and 30″ in declination. The first results, including new estimates of the anisotropy of background radiation at the scales of (l > 3000) and noise from discrete radio sources in the wavelength range between the NVSS and IRAS catalogs are listed.     

Decoupling the host and nuclear spectra of type I AGNs using integral field spectroscopy: A test on 3C 120

We have developed a new technique to decouple the spectra of the host and the nucleus of type I AGNs using integral field spectroscopy data. The technique is a simple extension of methods widely tested in 2D imaging. We present here the results from applying the technique to data taken with INTEGRAL at the 4.2 m William Herschel Telescope on the Seyfert 1 radio-galaxy 3C 120. We obtained, for the first time, a clean spectrum of the host galaxy, without contamination from the nuclear source.     

Polarimetry of the twilight sky and stratospheric aerosol

We propose a modification of the method of polarimetric measurements of the twilight sky, traditionally performed in a zenith direction, to study physical properties of the stratospheric aerosol (at altitudes higher than 30 km). The measurements carried out in zenith directions as a rule limit phase angles by values of 80–100°. We suggest setting up the declination of the telescope equal to the declination of the sun and measuring the polarization degree of the twilight sky at different values of the right ascension. It will allow us not only to enhance the range of the phase angles but also to plan observations in a way to obtain data on the phase dependence of the polarization degree of the light scattered by atmospheric layers at different altitudes.     

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.