Jet-linked X-ray emission in radio-loud broad absorption line (BAL) quasars

1Magdalena Kunert-Bajraszewska, 1Krzysztof Katarzynski, 2Agnieszka Janiuk, 1Maciej Ceglowski ( 1Torun Centre for Astronomy, N. Copernicus University, 2Center for Theoretical Physics, Polish Academy of Sciences )

We have applied theoretical models to explain spectral energy distribution (SED) of three radio-loud broad absorption line (BAL) quasars: an extended hybrid object PG 1004+130 and two compact sources 1045+352 and 3C270.1.We modelled emission coming from the very inner part of the sources which account for more than 90% of the observed X-ray emission of the whole source. In our analysis we consider a scenario in which the observed X-ray emission from radio-loud BAL quasars can be a sum of inverse-Compton jet X-ray emission and optically thin corona X-ray emission. The studied compact objects 1045+352 and 3C270.1 are high-redshift, 1.604 and 1.532 respectively, quasars with strong radio cores. We argue that in the case of these two sources a non-thermal, inverse-Compton emission from the innermost parts of the radio jet can account for a large fraction of the observed X-ray emission. The large scale object PG 1004+130 with a peculiar radio morphology is a low-redshift (z=0.24) lobe-dominated BAL quasar with a weak radio core. In this case the modeled inverse-Compton jet X-ray emission is very low and the corona X-ray emission must account for most of the observed X-ray emission from this object. As already discussed in the literature, the X-ray emission coming from the outer parts of the radio jet and hotspots in the case of PG 1004+130 and 3C270.1 could have either synchrotron or inverse Compton (IC) origin, but it accounts for ~2% of the whole observed X-ray emission in that sources.

Physical modeling of the longterm radio to gamma-ray variability of 3C 279

Marc Türler ( ISDC, University of Geneva )

The correlation often observed in blazars between optical-to-radio outbursts and gamma- ray flares as observed by the Fermi Space Telescope suggests that the high-energy emission region shall be co-spatial with the radio knots, several parsecs away from the central engine.

This would prevent strong Compton scattering of seed photons from the accretion disk and the broad-line region, as is usually assumed to model the spectral energy distribution of flat spectrum quasars. While a pure synchrotron self-Compton (SSC) model has so far failed to explain the observed gamma-ray emission of these sources, the inclusion of the effect of multiple inverse-Compton (IC) scattering in the Klein-Nishina limit might solve the apparent paradox. Here, we present a physical, self-consistent SSC modeling of 20 years of observations of 3C 279.

We show that a model accounting for multiple IC scatterings of synchrotron photons in a shock-in-jet scenario can both reproduce the spectral energy distribution at a given time, and the main features of longterm radio to gamma-ray lightcurves.

What governs the bulk velocity of the jet components in active galactic nuclei?

BO CHAI, XINWU CAO, MINFENG GU ( Shanghai Astronomical Observatory )

We use a sample of radio-loud active galactic nuclei (AGNs) with measured black hole masses to explore the jet formation mechanisms in these sources. Based on the K\"{o}nigl's inhomogeneous jet model, the jet parameters, such as the bulk motion Lorentz factor, magnetic field strength, and electron density in the jet, can be estimated with the very long-baseline interferometry and X-ray data. We find a significant correlation between black hole mass and bulk Lorentz factor of the jet components for our sample, while no significant correlation is found between bulk Lorentz factor and the Eddington ratio. The massive black holes will be spun up through accretion, as the black holes acquire mass and angular momentum simultaneously through accretion. Recent investigation indeed showed that most supermassive black holes in elliptical galaxies have on average higher spins than black holes in spiral galaxies, where random, small accretion episodes (e.g., tidally disrupted stars, accretion of molecular clouds) might have played a more important role. If this is true, the correlation between black hole mass and bulk Lorentz factor found in this work implies that the motion velocity of the jet components is probably governed by the black hole spin. No correlation is found between the magnetic field strength at $10R_{\rm S}$ ($R_{\rm S}=2GM/c^2$ is the Schwarzschild radius) in the jets and bulk Lorentz factor of the jet components for this sample. This is consistent with the black hole spin scenario, i.e., the faster moving jets are magnetically accelerated by the magnetic fields threading the horizon of more rapidly rotating black holes. The results imply that the Blandford-Znajek (BZ) mechanism may dominate over the Blandford-Payne (BP) mechanism for the jet acceleration at least in these radio-loud AGNs.

VLBI follow-up observations for the large X-ray flares of Mrk 421

Kotaro Niinuma ( Yamaguchi University )

In earlier in 2010, and September 2011, the large X-ray flares of Mrk 421 were reported by Astronomer’s Telegram (ATel #2368, ATel #2444, and ATel #3637). Mrk 421 is one of the best sources for studying the most compact regions in blazars, because of its proximity. In order to examine the behavior inside the sub-pc region by conducting the dense VLBI monitoring soon after the large flare, we carried out quick & multi-epoch follow-up observations for these flares using the Japanese VLBI network (JVN) array at an interval of two weeks ~ three weeks. Here we reported the results of the JVN observations for these large X-ray flares.

Particle acceleration by Magnetic Reconnection and the high energy spectrum of AGNs

1Behrouz Khiali, 1Elisabete Maria de Gouveia Dal Pino, 2Helene Sol, 1Grzegorz Kowal, 3Maria Victoria del Valle ( 1IAG-USP, University of São Paulo, 2Observatoire de Meudon, France, 3 IAG-USP, Univeristy of São Paulo, Brazil & IAR, CONICET, Argentina )

Very energetic particles are ubiquitous in astrophysical environments and the origin of UHECR is still an open question. Likewise, very high energy observations of AGNs and GRBs with the Fermi and Swift satellites and ground based gamma ray experiments (HESS, VERITAS and MAGIC) are challenging current theories of particle acceleration, mostly based on the acceleration in shocks, which try to explain how particles are accelerated to energies above TeV in regions relatively small compared to the fiducial scale of their sources. Recent MHD studies have revealed that particle acceleration in magnetic reconnection sites can be rather efficient since a 1st order Fermi process occurs there (de Gouveia Dal Pino & Lazarian 2005; de Gouveia Dal Pino et al. 2010; Kowal et al. 2011, 2012). In this talk, we discuss this acceleration mechanism in the framework of AGNs, considering that magnetic reconnection events can be very frequent in the inner regions of the corona of the accretion disks, or in the jets. We compute the corresponding acceleration rate and the relevant loss rates in order to reproduce the observed high energy spectrum of different classes of AGNs. We consider both leptonic and hadronic models and compare the efficiency of such acceleration processes with alternative acceleration mechanisms.

Two populations in Young Radio Galaxies

1Jong-Hak woo, 1Dong-Hoon Son, 1Sang Chul Kim, 1Daeseong Park, 2Nozomu Kawakatu, 3 Tohru Nagao ( 1Seoul National University, 2Tsukuba University, 3Kyoto University )

We investigate the disk-jet connection in Young Radio Galaxies (YRGs) by comparing emission-line properties with radio luminosity and jet size. By combining new optical spectra for 21 YRGs with SDSS archival data for 15 YRGs, we use a sample of 36 low-redshift YRGs at z < 0.4. YRGs are classified in high- and low-excitation galaxies based on the relative strength of high-to-low excitation line strengths, suggesting that there are two populations in YRGs as similarly found in large radio galaxies. High-excitation galaxies (HEGs) have higher emission line luminosities than low-excitation galaxies (LEGs) at fixed black hole mass and radio luminosity, indicating that the Eddington ratio is higher in HEGs than in LEGs and that for given radio activity HEGs have higher accretion activity than LEGs. The difference between HEGs and LEGs is probably due to either mass accretion rate or radiative efficiency.

The radio-source population at 20 GHz

1Elaine Sadler, 2Elizabeth Mahony, 3Ron Ekers ( 1University of Sydney, 2ASTRON, Netherlands, 3CSIRO )

Our current understanding of the radio properties of active galactic nuclei (AGN) comes almost entirely from studies at frequencies of 5 GHz and below.With the recent completion of the Australia Telescope 20 GHz (AT20G) survey, which covers the entire southern sky to a limiting flux density of 40 mJy at 20 GHz, we can gain new insights into the high- frequency radio properties of AGN. It is now clear that the high-frequency radio sky, like the gamma-ray sky surveyed by the Fermi satellite, is dominated by flat-spectrum radio quasars and BL Lac objects, and so the AT20G source catalogue has become a valuable resource for identifying the radio counterparts of southern gamma-ray AGN from Fermi.

I will describe some of our recent work on the optical identification and general properties of the fainter AT20G sources, with a particular focus on the lower-redshift galaxy population.

The SEDs and some physical properties of Fermi blazars

1Fan Li, 1Jinming Bai, 2Xinwu Cao, 2Liang Chen, 3Zhongzu Wu ( 1Yunnan Astronomical Observatory, 2Shanghai Astronomical Observatory, 3Guizhou University )

Using public Fermi/LAT and Swift/BAT observations with a blazar sample selected from the LAT Bright AGN Sample(LBAS) and a one-zone leptonic model, we fitted their SEDs and depicted the distribution of the derived physical parameters. Studying their spectral properties, we find that FSRQs have many different physical characteristics with BL Lac objects such as the distribution of magnetic field, γ_b, Doppler factor, electron energy distribution, etc. Jet power of the sources are discussed in this paper. The SEDs allow us to estimate the total luminosity and write it as a function of observed radio or γ-ray luminosity. We find the perfect equality relations between the total luminosity and the injected power of relativistic electron above break energy γ_b in the comoving frame. This provides a strong evidence for the theories about the radiation cooling mechanism and the production of break power law of electron energy distribution. The anti-correlation between γ_b and the energy density U_B + U_r is still valid, which support the existence of blazar sequence, but our result tends to give a similar slops for FSRQs and BL Lac objects. Combining the statistical results, we discuss the causes of γ_b formation and the physical principle of blazar sequence. We prove that γ_b is such a point that the integral power of injected relativistic electrons is equal to the total radiation power above this point, but is greater than the total power of radiation under it.We also discuss some restrictions about the upper and lower limits of the electron energy distribution.

Implications for the Blazar Sequence and Inverse Compton Models from Fermi Bright Blazars

Liang Chen ( Shanghai Astronomical Observatory )

We use the accretion disk/corona$+$jet model to fit the multi-band spectral energy distributions (SEDs) of two unusual radio-intermediate/quiet quasars. It is found that the optical/UV emission of III Zw 2 is probably dominated by the emission from the accretion disk. The X-ray emission should be dominated by the radiation from the jet, while the contribution of the disk corona is negligible.

The optical/UV component in the SED of PG 1407+265 can be well modeled as the emission from the accretion disk, while the IR component is attributed to the thermal radiation from the dust torus with an opening angle $\sim 50^\circ$. If the X-ray continuum emission is dominated by the synchrotron emission of the jet, the source should be a ``high peak frequency blazar", which obviously deviates the normal blazar sequence. The observed SED can also be fitted quite well by the accretion disk/corona model with the viscosity parameter $\alpha=0.5$. The spectrum of the accretion disk/corona in PG 1407+265 satisfies the weak line quasar criterion suggested in Laor \& Davis.

Clumpy dust tori illuminated by the anisotropic radiation of accretion disks in active galactic nuclei

Jian-Jian He, Shuang-Nan Zhang ( Institute of High Energy Physics, CAS )

The physical mechanism responsible for the observed decrease of hot dust covering factor (CF) with luminosity (L) for active galactic nuclei (AGN) is still undetermined. Our model is consisted of mainly three ingredients for an AGN: (1) the dusty torus is made of dust clumps; (2) the dust clumps are illuminated (heated and sublimated) by the anisotropic radiation of the accretion disk; and (3) the thickness of the torus is determined from the observed fraction of type 1 AGN as a function of Eddington ratio. Our model can naturally explain the observed strong anti-correlation of CF-L, by considering different forms of dust clump distributions in the torus. The observed weaker anti-correlation between CF and black hole mass (M) is simply a consequence of the very weak or no dependence of Eddington ratio (Ledd) with M. Yet the observed much weaker anti-correlation between CF and Ledd is mostly due to the uncertainties in measuring M. Our model can thus reproduce successfully the observed main statistical properties of hot dust in AGNs.

The calculation of an accretion disc-corona model for kerr BH

1BEI YOU, 1XINWU CAO, 2YEFEI YUAN ( 1Shanghai Astronomical Observatory, 2University of Sciences and Technology of China )

We calculate the structure of a standard accretion disk with corona surrounding a massive Kerr black hole in general relativistic frame, in which the corona is assumed to be heated by the reconnection of the magnetic fields generated by buoyancy instability in the cold accretion disk. The emergent spectra of the accretion disk-corona system is calculated by using the relativistic ray-tracing method. We propose a new method to calculate the emergent Comptonized spectra from the coronae dividing layers in the coronae. The resulted spectra of the disk-corona systems with a modified $\alpha$-magnetic stress show that both the hard X-ray spectral index and the hard X-ray bolometric correction factor $L_{\rm bol}/L_{\rm X,2-10keV}$ increase with the dimensionless mass accretion rate, which are qualitatively consistent with the observations of active galactic nuclei (AGNs). The ratio of the X-ray luminosity to the optical/UV luminosity increases with the viewing angle, while the spectral shape in the X-ray band is insensitive with the viewing angle. We find that the spectral index in the infrared waveband is dependent of the mass accretion rate and the black hole spin parameter $a$, which deviates from $\nu^{1/3}$ as expected by the standard thin disk model. The observations on the polarized infrared continuum emission from AGNs can be used to constrain the black hole spin parameter with our model calculations.

VLA polarization studies of M87 jet

Juan Carlos Algaba, Keiichi Asada, Masanori Nakamura ( Academia Sinica, Institute of Astronomy and Astrophysics )

We present multi-epoch VLA observations toward the M87 jet over 3 years to investigate the polarization property at frequencies of 8, 15, 22, and 43 GHz. Three-dimensional magnetic structure is examined by means of stacked images of the total intensity as well as the fractional polarization. By comparing our result with Owen et al. and Perlman et al., we discuss about the dynamical role of the magnetic field in the structure of the M87 jet. We also argue the distribution of the spectral index and rotation measure of the jet on the VLA scale at high frequencies.

The Urumqi Survey for Rapid Variability in Compact Radio Sources

1Jun Liu, 1Xiang Liu, 1Lang Cui, 1Hua-Gang Song, 1Zhen Ding, 2Thomas Krichbaum, 2Nicola Marchili, 2Lars Fuhrmann, 2Anton Zensus ( 1Xinjiang Astronomical Observatory, CAS, 2Max- Planck-Institut für Radioastronomie )

In the cm-regime rapid flux density variations on timescales of the order of a day or less (Intra-Day Variability, IDV) are frequently seen in compact flat spectrum radio sources. Aiming at study the origin of such rapid variability, we initiated a project to monitor a large sample of compact flat spectrum radio sources which were selected from the CRATES catalogue of Healey et al (2007). From this catalogue we monitored 456 northern sky radio sources with the Urumqi 25m radio telescope at 5 GHz with dense time sampling. The scientific purpose of this project is a statistical study for a large sample of IDV sources with the aim to search for possible correlations between IDV and source properties (such as VLBI jet speed or gamma-ray loudness) and correlations between source position on the sky and fore-ground emission. The project, which was launched in Feb. 2010, is still ongoing. In this talk we will present and discuss first results.

Faraday Effects In Linear And Circular Polarizations of Discs And Jets Lei Huang ( Shanghai Astronomical Observatory, CAS )

We provide precise fitting formulae for Faraday conversion and rotation coefficients in uniformly magnetized relativistic plasmas. The formulae are immediately applicable to RM and RRM production of plasmas in arbitrary energy distribution. The exact coefficients are found essential for reliable LP and CP interpretation and prediction of relativistic discs and jets. We apply them in Sagittarius A* and M87.

Intra-day Variability of Quasar 1156+295 at 4.8GHz

1Baorong Liu, 1Xiang Liu, 1Jun Liu, 2Nicola Marchili, 2Thomas Krichbaum ( 11 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150 Science 1-Street, Urumqi 830011, PR China 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, PR China, 2Max-Plank-Institut f r Radioastronomie, Auf dem H gel 69, u u 53121 Bonn, Germany )

We present the result of 1156+295 in our IDV (intra-day variability) monitoring program from 2007 to 2009, with the Urumqi 25m radio telescope at 4.8 GHz. The source exhibits a violent variability, the light curves and modulation indices of the intra-day variations have been obtained. We also analyze the characteristic variability time-scales of the IDV.

Near-infrared/optical ensemble variability of cataloged AGNs 1Shinjirou Kouzuma, 2Hitoshi Yamaoka ( 1Chukyo University, 2Kyushu University )

We present the properties of the ensemble variability $V$ for nearly 5000 active galactic nuclei (AGNs). The sample AGNs were extracted from two AGN catalogs, namely the catalog of Quasars and Active Galactic Nuclei (13th Edition) and the SDSS-DR7 quasar catalog. We cross-identified the sample AGNs with three near-infrared point source catalogs (namely, 2MASS, DENIS, and UKIDSS/LAS catalogs), and extracted 2MASS-DENIS or 2MASS-UKIDSS counterparts for cataloged AGNs. Using redshifts listing in the AGN catalogs, sample AGNs were divided into subsets according to whether near-infrared light originates by optical emission or by near-infrared emission in the rest frame, and we examined correlations of the near-infrared/optical ensemble variability with a physical parameter (i.e., the rest-frame wavelength, redshift, luminosity, and rest-frame time lag). It is notable that the near-infrared variability shows a negative correlation with rest-frame time lag (i.e., a negative slope in structure function), which is an opposite correlation to the well-known positive correlation in the optical. In addition, there is a positive correlation between near-infrared variability amplitude and radio loudness. We mainly discuss the near-infrared variability properties of cataloged AGNs.

The origin of radio emission in low luminosity AGNs hu liu, qingwen wu ( School of Physics, Huazhong University of Science and Technology )

Low luminosity AGNs occupy an important fraction of nearby galaxies, and most of them is radio loud(Ho 2008). However, the origin of their radio emission is still an open issue, since no obvious large-scale relativistic jet observed in them (only a small fraction observed with jet, e.g., M87). We explored the origin of the radio emission in low luminosity AGNs. We firstly investigate the possible contribution from the non-thermal electrons in the advection dominated accretion flow (ADAF, as in Sgr A* in Yuan et al. 2003), and find that it is difficult to explain most of LLAGNs with reasonable parameters. We further explored the possible contribution from the outflows of the ADAF, and find it can reasonably explain the radio emission of most LLAGNs. Therefore, we suggest that the radio emission from LLAGNs may dominated by the sub-relativistic outflows.

GRAVITATIONAL WAVES FROM EJECTION OF JET SUPERLUMINAL COMPONENTS AND PRECESSION OF ACCRETION DISKS DYNAMICALLY DRIVEN BY BARDEEN-PETTERSON EFFECT

1Herman Mosquera Cuesta, 2Luis Henry Quiroga Nuñez ( 1Departmento de Fisica, Universidade Estadual Vale do Acarau, Sobral, Ceara, Brazil. Instituto de Cosmologia, Relatividade e Astrofisica (ICRA-BR). Centro Brasileiro de Pesquisas F ́ısicas, , Rio de Janeiro, Brazil., 2Department of Physics, National University of Colombia )

Jet superluminal components are recurrently ejected from active galactic nuclei, microquasars, T-Tauri star, and several other astrophysical systems, including gamma-ray burst sources. The mechanism driving this powerful phenomenon is not properly settled down yet. In this article we suggest that ejection of ultrarelativistic components may be associated to the superposition of two actions: precession of the accretion disk induced by the Kerr black hole (KBH) spin, and fragmentation of the tilted disk; this last being an astrophysical phenomenon driven by the general relativistic Bardeen-Petterson (B-P) effect. As fragmentation of the accretion disk takes place at the B-P transition radius, the incoming material that get trapped in this sort of Lagrange internal point will forcibly precess becoming a source of continuous, frequency-modulated gravitational waves. At resonance blobs can be expelled at ultrarelativistic velocities from the B-P radius. The launching of superluminal components of jets should produce powerful gravitational wave (GW) bursts during its early acceleration phase, which can be catched on the fly by current GW observatories. Here we compute the characteristic amplitude and frequency of such signals and show that they are potentially detectable by the GW observatory LISA.

Detection of variability in CGRaBS~J0211+1051: A multiwavelength study

Kiran BALIYAN, Sunil Chandra, Shashikiran Ganesh (Physical Research Laboratory, Ahmedabad 380009, India)

Study of the correlated variations in different wavebands provides important clues to the emission processes responsible for the emissions in AGNs by putting stringent constraints on several models proposed for their explanation. We report the detection of high polarization in the first detailed optical linear polarization measurements on the object CGRaBS J0211+1051, which flared in gamma-rays on 2011 January 23 as reported by Fermi team. The source has been brightening since 2008 when it was at V=15.6 magnitude. The observations were made during 2011 January 30 - February 3 using photo-polarimeter mounted at the 1.2m telescope of Mt Abu InfraRed Observatory(MIRO). The source was also observed, mainly in R-band, using 1kx1k EMCCD mounted at the 50cm telescope dedicated to the variability study (ATVS) at MIRO. CGRaBS J0211+1051 was detected to have >21 % degree of polarization (DP) with almost steady position angle (PA) at 43 degree on 2011 January 30. During January 31 and February 1, 2011 while degree of polarization shows some variation, position angle remains steady for the night. The observations during January 30 to February 1, 2011 were made in white light to maximize the signal. However, to study any wavelength dependence of polarization (WDP), measurements on February 2 & 3 were made through B, V and R broad bands. Several polarization flashes occurred during February 2 and 3 resulting in changes in the DP by more than 4% at short time scales (~ 17 to 45 mins). The intra-night variability shown by the source appears to be related to the turbulence in the relativistic jet due to the interaction of the shocks with features in the pc-scale jet. A mild wavelength dependence of polarization is noticed during the nights of February 2 & 3, in which degree of polarization increases with frequency. The source exhibited significant inter-night variations in the degree of polarization (changed by about 2 to 9%) and position angle (changed by 2 to 22 degree) during the five nights of observations. The variations appear to be non-periodic and asymmetric in nature and therefore could be caused by the intrinsic processes in the jet. Sudden change in the PA accompanied by a rise in the DP could be indicative of the fresh injection of the plasma in the jet. The detection of high and variable degree of polarization categorizes the source to be a low energy peaked blazar (LBL). In order to confirm this possibility, we analyzed the data available in the radio, UV, X-ray and gamma-rays from MOJAVE, Metsahovi observatory (radio), SWIFT (optical, UV and X-ray) and Fermi (gamma- rays) quasi-simultaneous with our observations. We constructed light curves in various energy bands to study correlated variations. The spectral energy distribution constructed from these observations reveal that the synchrotron peak lies in optical region. This confirms the LBL status of the source and also indicates that extent of polarization can also be used to tentatively classify blazars.

The detailed results will be discussed at the conference.

Drift scanning surveys conducted at 1.42 GHz using a fast Fourier transform processor

Sumiko Kida, Kuniyuki Asuma, Tsuneaki Daishido ( Waseda University ) sumiko_k@aoni.waseda.jp

Drift scanning surveys are conducted at 1.42 GHz using eight 20-m dishes at the Waseda Nasu Observatory. In January 2010, a space-based fast Fourier transform processor consisting of a two-step Radix-4 based on a field-programmable gate array was introduced; this processor can be used to carry out complex analog-to-digital conversions with Nyquist rate sampling. The detection sensitivity of this processor is three times higher than that of the earlier analog diode detector. Two wide-field surveys were conducted in 2010 and 2011. In these surveys, the observable region was continuously observed at every declination 0.5 degree. Approximately five hundred radio sources were detected. Fifteen active radio sources such as the Fermi LAT bright sources and Tev Cat gamma-ray sources were included. In addition, an unidentification burst was detected in 2010. This burst was detected at Galactic latitude b=39 degree and the burst duration was up to two days. This burst has a QSO (SDSS J164400.91+323445.5) as a possible counterpart. It was not detected in 2011. We report on these detection results. We aim to quickly detect the variable source or the burst by repeatedly monitoring the wide field by drift scanning.

The Dynamic Evolution of Compact Symmetric Objects

1Tao An, 2Willem Baan ( 1Shanghai Astronomical Observatory, China, 2ASTRON, The Netherlands )

The dynamic evolution of extragalactic radio sources is usually described as the variation of the radio luminosity with the growing size or age. According to the self-similar evolution models, the dynamic evolution of radio sources can be divided into four distinct stages which are characterized by the dominant energy-loss processes and different density distribution of the ambient medium. Here we shall report our recent investigations on the evolutionary behaviors of the youngest population of radio sources named Compact Symmetric Objects (CSOs). A subsample consisting of 24 CSOs with known redshift and hotspot advance velocity is used for this analysis. The relations among the observables such as radio power, hotspot separation, hotspot advancing velocity, and kinematic age, are found to be generally consistent with the self-similar model predictions for individual sources that reflect the varying density structure of the ambient medium in the host galaxy. The age and size statistics suggest that a large fraction of CSOs would not evolve into extended doubles. The phenomenology CSO supports a division into two classes of radio sources based on radio luminosity that extends across all size scales.

Two in one: dual radio-emitting nucleus in the quasar SDSS J1425+3231

1Sandor Frey, 2Zsolt Paragi, 3Tao An, 4Krisztina Gabanyi ( 1FOMI Satellite Geodetic Observatory, Hungary, 2Joint Institute for VLBI in Europe, The Netherlands, 3Shanghai Astronomical Observatory, China, 4Konkoly Observatory, Hungary )

SMBH pairs should be ubiquitous according to hierarchical galaxy formation scenarios. Yet the number of presently confirmed dual AGNs is small. High-resolution radio interferometric observations provide a direct way to verify the duality, provided that both AGNs are in an evolutionary phase when some activity is going on in the radio. SDSS J1425+3231 (z=0.478) was recently found to have double-peaked narrow [O III] optical emission lines, and is thought to harbour a dual AGN system, with two SMBHs separated on the kpc scale. We report here the VLBI imaging results from the observations made with the European VLBI Network (EVN) at 1.7 GHz and 5 GHz frequencies in 2011. Two compact components are detected at sub-mJy flux density levels and they are separated about 2.6 kpc. The compactness and high brightness temperatures indicate an AGN origin of the radio emission in both sources. The weaker component remained undetected at 5 GHz, due to its steep radio spectrum. While high-resolution radio interferometric imaging is not an efficient technique to blindly search for dual AGNs, it is an invaluable tool to confirm the existence of selected candidates.

A Decelerating Jet in XTE J1752-223

Jun Yang

The X-ray transient XTE J1752-223 is a new Galactic stellar-mass black hole candidate. With the European VLBI Network (EVN) and Very Long Baseline Array (VLBA), we observed multiple transient ejecta in the radio regime during its first known X-ray outburst. The proper motion evolution in two ejecta shows direct evidence for a mildly relativistic jet, strongly decelerating at just ~100 milliarcsecond angular separation from the core, which has never been observed in black hole X-ray binaries before. At the end of the outburst sequence, we detect the core of the system as it returns from its radio quenching state.

Core-shift effect in a microblazar

1Lisa Zimmermann, 1Maria Massi, 2Eduardo Ros ( 1Max Planck Institute for Radio Astronomy, Bonn, Germany, 2University of Valencia, Spain )

LS I +61°303 is one of the few GeV and TeV emitting X-ray binaries with a prominent, wellstudied modulated radio and gamma-ray emission. The origin of the gamma-rays, in LSI+61°303 and in X-ray binaries in general, is strongly debated and explained as either leptonic or lepto-hadronic. To disentangle these processes, the true nature of this object needs to be understood. Two models exist for this source, the young pulsar and a microquasar model. Recently, radio spectral index analysis and high energy results, e.g. from Fermi-LAT, rekindled the microquasar model and re-analysis of archival VLBA data by Massi, Ros & Zimmermann (2012, A&A, u.r.) now confirm double-sided and fast switches to one-sided structures. This is not compatible with a pulsar, though well explainable in a microquasar scenario with a jet pointing close to our line of sight - a microblazar, i.e. the galactic version of the extragalactic blazars. Moreover, we observe in LS I +61303 the first case of a core-shift displacement in a microquasar - an effect well known from AGN. The part of the jet, which is optically thick at the observing frequency, is rather displaced from the system center. In LS I +61303, the core position of the jet traces a clear ellipse with a period of ~28d and a diameter much bigger than the orbit. Our hypothesis is that this ellipse is the cross-section of the precession cone of the jet and its period a first estimate of the precession period.

A different view of the radio - gamma-ray connection in blazars

1Francesco Massaro, 2Raffaele D'Abrusco, 2Alessandro Paggi, 3Gino Tosti ( 1Stanford University, 2SAO, 3University of Perugia )

Recently, we discovered that blazars, the rarest and the largest known class of gamma-ray sources, can be recognized and separated from other extragalactic sources dominated by thermal emission using the IR colors.

In particular, we showed how it is possible to selected gamma-ray blazar candidates only on the basis of their IR colors using the archival observations of the Wide-Field Infrared Survey Explorer (WISE). I will present the analysis of the infrared properties of the radio sources with a flat radio spectrum

listed in the CRATES catalog, to search for gamma-ray blazar candidates. We found that all the sources in the CRATES catalog that are associated with gamma-ray sources in the second Fermi catalog (2FGL), have peculiar IR colors consistent with those of the blazars, with only two exceptions. In addition, I will show that the association of radio sources in the 2FGL sources as blazars, based on the WISE colors method has efficiency and completeness comparable to the association method involving the existence of radio counterparts for the gamma-ray detections.

Study of the radio-X-ray properties of AGN based on their complete sample

Areg Mickaelian, Gurgen Paronyan, Hayk Abrahamyan ( Byurakan Astrophysical Observatory (BAO) )

A complete X-ray selected sample of 4401 AGN was compiled based on two ROSAT-based catalogs: Hamburg RASS Catalog (HRC, ROSAT BSC sources) and Byurakan Hamburg RASS Catalog (BHRC, ROSAT FSC sources), respectively, both based on of optical identifications of ROSAT sources by means of the low-dispersion spectra of the Hamburg Quasar Survey (HQS). The sample contains sources with count rate of photons CR ≥ 0.04 ct/s in the area with galactic latitudes |b|≥ 30° and declinations δ ≥ 0°. 3362 of them are listed in the 13th version of the Catalogue of AGN by Veron-Cetty and Veron, and others are AGN candidates classified from low-dispersion spectra. We have made multiwavelength investigation in all wavelength ranges (gamma, X-ray, UV, optical, IR and radio) using the recent available all-sky or large-area catalogues. An attempt was made to find connections between the radiation fluxes in different bands for different types of sources, and identify their characteristics. Especially efficient were relations between X-ray and radio fluxes at different wavelengths (6cm (GB6), 21cm (NVSS, FIRST), 49cm and 92cm (WENSS) and 198cm (7C)) revealing a number of objects with extremely high X-ray and radio emission.

Joint radio/X-ray coexistance in the COSMOS field Vibor Jelic ( ASTRON )

The COSMOS survey is designed to probe the formation and evolution of galaxies as a function of cosmic time and large scale structure environment. The survey covers a 2 sq. deg area close to celestial equator with multi-wavelength imaging from X-ray to radio wavelengths, including HST/ACS imaging and optical spectroscopy. During my talk I will present results on joint radio/X-ray coexistance in the COSMOS field, and discuss a source where the observed extended X-ray emission arise from non-thermal processes related to radio galaxy lobes.

Investigation of possible Radio-Gamma Ray connection in FSRQ pks1510-089

1Sunil Chandra, 2Kiran Singh Baliyan, 3Shashikiran Ganesh ( 1Physical Research Laboratory, Ahmedabad, Gujarat, India, 2Physical Research Laboratory, Ahmedabad Gujarat, India, 3 Physical Research Laboratory, Ahmedabad, Guajarat, India )

Blazars are subclass of Active Galactic Nuclei, consistsing a jet of a highly relativistic plasma very close to our line of sight (<=15 deg). Blazars are well known for non-thermal continuum emission over the entire energy spectrum, i.e ranging from radio to VHE Gamma- Rays through Optical/X-ray energy bands. Blazars broadly comprises the Flat Spectrum Quasars (FSRQs) and BL Lac Objects (BLLacs). The main differences between BL Lacs and FSRQ are, to first order, that the FSRQ are more distant, more luminous, and have stronger emission lines.

In the present study we are investigating FSRQ pks1510-089 for variability of all possible time scales in different energy bands and try to get possible connections between Radio to Gamma Rays . The present understanding of energy mechanism in these source strengthen the possibility of some correlation.

Monitoring of Jets in Active Galactic Nuclei with VLBI Experiments (MOJAVE) team is regularly monitoring the source in Radio and FERMI/AGILE in Gamma-Rays as well. The published/Archived data for other waveband along-with optical polarization and photometric monitoring data taken from 1.2 m optical telescope at Mt. Abu Infrared Observatory (MIRO) is used for the study. The preliminary results of this study will be presented during the meeting.

FR dichotomy, accretion modes and environmental factors in the local Universe

1Melanie Gendre, 2Philip Best, 3Jasper Wall ( 1JBCA - University of Manchester, 2IfA - Royal Observatory, Edinburgh, 3University of British Columbia )

Active galactic nuclei (AGN) comprise the majority of currently observed radio galaxies, and the Fanaroff-Riley (FR) categorisation provides a classification of extended AGN. The FRI objects have the highest surface brightness along the jets near the core, while FRII sources show the highest surface brightness at the lobe extremities, as well as more collimated jets.

This FR dichotomy is based purely on the appearance of the radio objects, and the mechanisms differentiating the two populations are still unknown. Two main streams of models exist to explain these differences in morphology. Extrinsic models are purely based on the source environment, where inter-galactic medium density is the differentiating factor: jets of sources in higher/lower density mediums experience a higher/lower degree of resistance, yielding sources with FRI/FRII structures respectively. Intrinsic models, on the other hand, suggest that the dichotomy arises from differences in the properties of the central black hole. In these scenarios, low-excitation galaxies (LEG) have jets produced by low accretion-flow rate which are generally weak and mostly display FRI-type structure, whereas high-excitation galaxies (HEG) have higher accretion flow rates giving rise to stronger, mainly FRII-type jets. If the FR dichotomy was fully dependent on the jet properties, FRI/II sources would be systematically associated with LEG/HEG respectively. However, in several cases, small subsets of FRIs were found in HEG samples, as well as some FRIIs being associated with LEGs.

The presented work is based on the CoNFIG catalogue, a sample of radio sources at 1.4- GHz, including FRI/FRII/Compact morphology classifications, optical identifications and redshift estimates. High/low excitation classification and environmental richness factor of a subsample of local (z<0.3) CoNFIG extended galaxies were compiled to investigate the possible FR morphology-accretion mode-environment relations. The sub-sample contains 208 sources, including 75 FRIs and 108 FRIIs, 76% of which have available spectra, mostly from SDSS.

We found that there is a broad overlap of properties, although FRIs generally reside in denser environments that FRIIs. More interestingly, a source found in a rich environment has a very high probability of being both LEG and FRI, fitting with scenarios in which cooling occurs from the X-ray halo. In addition, FRIs broadly show the same RLF shape in all 4 classes (poor/rich HEG/LEG), while FRIIs show more evidence for a switch between HEGs at high luminosities to LEGs at low luminosities.

Comparison and Analysis in Variation of OJ 287, 0716+714 and BL Lacertae

Hongtao Wang ( LangFang Teachers College )

OJ 287 is a low peak frequency BL Lac object which has violent action, the energy spectrum distribution in low frequency is similar with the other two TeV BL Lac objects(0716+714 and BL Lacterate), but we didn't detect it's TeV gamma ray by the Cherenkov telescope. we compare difference and similarities in the aspects of the minimum variation period and time delay among 22GHz, 37GHz and B band. the causes of 0J 287 without gamma-ray are studied and analyzed. The results are as follows: (1).In the aspect of minimum variability period, OJ 287 is smaller than the other two objects in 37 GHz and B band, OJ 287 is correspond to 0716+714 in 22GHz, is less than BL~Lacertae. but we can't detect the TeV gamma-ray because of smaller variation period, it shows the radiation from OJ 287 in TeV band has much less connections with the minimum variation period in 22GHz, 37GHz and B band. (2)In the aspect of time delay, the time delay of OJ 287 in B-37GHz is longer than 0716+714, shorter than BL Lacertae; the time delay is shorter than 0716+714 in 37-22GHz, but the time delay of BL Lacertae is negative, it means that the 22GHz is lead the 37GHz. By comparison and analysis the results in time delay, we can't find some obvious differences among OJ 287, 0716+714 and BL Lacertae. In the aspect of SED, the SED of OJ 287 is steeper than the other, so the Cherenkov telescope can't detect the TeV gamma-ray radiation from OJ~287,but we don't know how the steeper SED in TeV band affect the variation in the low energy band.

Fermi active galactic nuclei at parsec scales

1Yuri Kovalev, 2Leonid Petrov ( 1ASC Lebedev, 2Astrogeo Center )

It was established previously that over 60% of 2FGL objects with |b|>10 deg have associations with compact extragalactic radio sources detected in all-sky VLBI surveys. We observed with VLBA+GBT radio weak AGN associations of Fermi detections with no prior knowledge on their parsec-scale properties and got almost 100% detection rate. Resulting full Fermi-VLBI sample data is used to perform population analysis of blazars. We derived VLBI positions of all Fermi associations with a sub-mas accuracy level and evaluated random and systematic position errors of the 2FGL catalogue. Ongoing activity to find associations of non-identified Fermi 2FGL detections will also be discussed.

Discovery of thermal plasma within the giant radio lobes of CentaurusA

Ilana Feain, Shane O'Sullivan, Ron Ekers ( CSIRO Astronomy & Space Science ) Using the Australia Telescope Compact Array and the Parkes 64 m radio telescope at 1.4 GHz, we have imaged the full extent (9x5 degrees) of Centaurus A, the nearest radio galaxy with a spatial resolution of ~600 pc. We have resolved the ~500kpc giant radio lobes with approximately five times better physical resolution compared to any previous image, making this the most detailed radio continuum image of any radio galaxy to date. In this talk I will describe the results of this large imaging program which includes full polarisation. Through the effect of Faraday rotation, we have discovered the presence of thermal plasma distributed on large scales within the giant lobes of the radio galaxy, Centaurus A. Our results support a scenario in which the majority of the thermal material was originally entrained from the host galaxy and then lifted out into the lobes by the buoyant relativistic plasma. The uniform number density of the thermal plasma is nth 2x10-4 cm-3. We estimate the total mass of the thermal gas within the lobes is ~6x108 Mdot.The presence of such a large amount of hidden baryons held within the lobes introduces a previously unaccounted aspect of feedback between radio galaxies and their environments.

AGN contribution to the total mid-infrared emission of Spitzer-selected luminous infrared galaxies

Obi I.A (1,2), Okere I.B (1,2), Okoh D.I (1), and Okeke P.N (1) (1 Centre for Basic Space Science (CBSS), Nsukka, Nigeria; (2) Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria)

In this paper, we present a quantitative estimate of the active galactic nuclei (AGN) / starburst(SB)

contribution to the mid-infrared (MIR) and the total infrared (IR, 8 − 1000 μm) for a sample of 44

nearby local luminous infrared galaxies (LIRGs, infrared [8 – 1000µm] luminosities of Log LIR = 11-

11.9 Lʘ ) from the Spitzer Space Telescope observations. We make a spectral decomposition of the

Spitzer/ Infrared Spectrograph (IRS) low-resolution (SL+LL) spectra observed at the entire spectral

range of 5 - 38µm into AGN and SB components by making use of the Nenkova's clumpy dusty torus

model and star-forming galaxy templates respectively. By employing this method and diagnostics

based on the properties of the [Ne V]14.32µm and [Ne V]24.3µm ,[Ne II]12.8µm, [Ne III]15.56µm and [O

IV]25.89 µm fine structure gas emission lines, continuum emission, the 6.2 μm polycyclic aromatic

features(PAHs) and the 9.7µm silicate feature, we show that 58% of local LIRGs contain an AGN, but

the AGN contribution to the bolometric luminosities is significant only in ~ 7 % of the sources. This

confirms that the vast majority of Local LIRGs are dominated by star formation activity. We also show

from comparison of our results with that from literature that the fraction of local LIRGs IR emission

coming from an AGN as estimated in the mid infrared is approximately two times larger than that

seen in normal galaxies and about four to five times lower than that seen in local ULIRGs. The LIRGs

dominated by AGN tend to be more luminous at 24 μm than at other wavelengths and also to have IR

colors warmer than starburst dominated LIRGs. However, we find no strong correlations between the

fraction of IR luminosity from an AGN and the 24 μm or total luminosity.

The Gamma-ray View of Low-luminosity AGNs with Fermi

Rodrigo Nemmen ( NASA GSFC )

Low-luminosity active galactic nuclei (LLAGNs) represent the bulk of the AGN population in the present-day universe and they trace the low-level accreting supermassive black holes. I will present an analysis of Fermi gamma-ray observations of LLAGNs. I will discuss how these observations can be used to constrain the production site of gamma-rays and potentially disentangle the contribution of the hot accretion flow and jet at high energies, which is an outstanding issue in the the study of LLAGNs.