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We estimated values of spin, mass, and inclination angle for sample of 42 red quasars. Our estimations show that two objects: F2MS J1113+1244 and F2MS J1434+0935 with the highest Eddington ratios may have geometrically thick disk. Six objects: SDSS J0036‐0113, S82X 0040+0058, S82X 0118+0018, S82X 0303‐0115, FBQS J1227+3214, S82X 2328‐0028 may have "retrograde" rotation. Analysis of estimated spin values shows that red quasar population may contain Seyfert galaxies and NLS1. [ABSTRACT FROM AUTHOR]

Radiation‐magnetohydrodynamic simulation of the active galactic nuclei predicts the presence of the strong accretion disk wind, which gets unstable far from the central region and turns into gas clumps. These inner wind and outer clumps may be actually observed as the ultrafast outflows (UFOs) and the clumpy absorbers, respectively. We call this picture as the "hot inner and clumpy outer wind model." Observationally, it is challenging to place constraints on the origin of the UFOs and clumpy absorbers due to complicated spectral variations. We developed a novel method, "spectral‐ratio model fitting," to resolve parameter degeneracy of the clumpy absorbers and other spectral components. In this method, the parameters of the absorber in the line of sight are estimated from the ratio of the partially absorbed spectrum to the non‐absorbed one. We applied this method to the narrow‐line Seyfert 1 galaxy IRAS 13224–3809 observed by XMM‐Newton in 2016 for 1.5 Ms, where the source showed extreme spectral variability and complex absorption features. As a result, we found that the soft spectral variation is mostly explained by a change in the covering fraction of the mildly‐ionized clumpy absorbers, and that these absorbers are outflowing with such a high velocity that is comparable to that of the UFO (∼0.2–0.3 c). [ABSTRACT FROM AUTHOR]

Tidal disruption events (TDEs) occur when a star passes close to a massive black hole so that the tidal forces of the black hole exceed the binding energy of a star and cause it to be ripped apart. Part of the matter will fall onto the black hole, causing a strong increase in luminosity. Such events are often seen in the optical or the x‐ray (or both) or even at other wavelengths such as in the radio, where the diversity of observed emission is still poorly understood. The XMM‐Newton catalog of approximately a million x‐ray detections covering 12832$$ {}^2 $$ degrees of sky contains a number of these events. Here I will show the diverse nature of a number of TDEs discovered in the catalog and discuss their relationship with quasi‐periodic eruptions. [ABSTRACT FROM AUTHOR]

The non‐linear correlation between the UV and X‐ray emission observed in active galactic nuclei remains a puzzling question that challenges accretion models. While the UV emission originates from the cold disk, the X‐ray emission is emitted by a hot corona whose physical characteristics and geometry are still highly debated. The jet emitting disk‐standard accretion disk (JED‐SAD) is a spectral model stemming from self‐similar accretion‐ejection solutions. It is composed of an inner highly magnetized and hot accretion flow launching jets, the JED, and an outer SAD. The model has been successfully applied to X‐ray binaries outbursts. The AGN UV–X‐ray correlation represents another essential test for the JED‐SAD model. We use multiple AGN samples to explore the parameter space and identify the regions able to reproduce the observations. In this first paper, we show that the JED‐SAD model is able to reproduce the UV–X‐ray correlation. [ABSTRACT FROM AUTHOR]

Tidal disruption events (TDEs) are usually discovered as bright transients, either in the X‐ray or optical/UV band. These events are often characterized by a "super‐soft" emission in the X‐ray band, which has not been observed in any other extragalactic source, with few exceptions (novae and supersoft active galactic nuclei, AGN), which can however be distinguished by their optical behavior. By cross‐correlating optical and X‐ray catalogs and filtering for extremely steep (photon index Γ > 3) and highly luminous (LX > 1041 erg s−1) objects in external galaxies nuclear regions, we aim to detect overlooked TDEs. With our blind search, we retrieved about 60 sources. Among these, 36 sources show steeper‐than‐usual spectra, but, with their optical classification, can be considered standard AGNs. Instead, fifteen are well‐studied supersoft AGNs or TDEs, demonstrating the efficiency of our selection. The remaining 9, are previously unknown sources. Five are extremely soft‐excess dominated AGNs, while 4 sources are optima TDE candidates. In this work, we focus on these 4 latter sources. [ABSTRACT FROM AUTHOR]

By applying different statistically robust methods, we analyze the time lag between the continuum and ionized line‐emission (Mg II line) light curves for the distant bright quasar CTS C30.10 (redshift z∼0.9). The data were obtained by the 10‐meter South African Large Telescope (SALT) telescope in South Africa. In detail, we demonstrate the application of several methods using the interpolated cross‐correlation function (ICCF), discrete correlation function (DCF), z‐transformed discrete correlation function (zDCF), von Neumann estimator, and the JAVELIN code package. In particular, we discuss the uncertainties of these methods. In conclusion, we find that the quasar lies on the broad‐line region (BLR) size—monochromatic luminosity power‐law scaling, RBLR∝L51001/2, which was already confirmed for low‐redshift sources. In case, the BLR size–luminosity relation holds for other distant sources, quasars could be used to probe cosmological models as "standard candles" complementary to supernovae Ia. [ABSTRACT FROM AUTHOR]

We present the results of our estimations of the polarization degree of broad line emission for the radio galaxies 3C 120, Mrk 335, Mrk 1501, and PG 2130 + 099. We derived the polarization degree for every broad line of 3C 120: Hα, Hβ, Hγ, and HeIλ5876 using the published data for the geometrical parameters and the structure of the broad line region (BLR) of 3C 120. We used published estimates of the geometrical thickness to the radius ratio for every broad emission line. The estimated vertical BLR structure corresponds to the disk‐like structure of this region in active galactic nuclei (AGN). Also for objects Mrk 335, Mrk 1501, and PG 2130 + 099, we estimated the polarization degree using inclination angle values from the literature. As a result, measuring the polarization degree of broad line emissions acquires the central meaning for determination of the geometrical parameters of the BLR in AGN. [ABSTRACT FROM AUTHOR]

The X‐ray emission from accreting black hole (BH) systems displays strong variability. Short reverberation lags are expected between the primary hard X‐ray continuum and the reprocessed disk emission. These lags depend on light‐travel distances, thus offering the opportunity to map the geometry of the innermost accretion flow. X‐ray reverberation lags have been observed in several BH accreting systems. In radio‐quiet active galactic nuclei (AGN), these lags scale with BH mass and point to a reprocessing region located close to the comptonizing X‐ray corona. On the other hand, reverberation lags detected in the hard state of some BH X‐ray binaries (BHXRB) suggest a different accretion flow geometry than in AGN, showing evidence of evolution as a function of luminosity. [ABSTRACT FROM AUTHOR]

The two stars of stellar binaries can be tidally disrupted by supermassive black holes (SMBHs) or supermassive black hole binaries (SMBHBs) in sequence. In this contribution, we review our recent study about double tidal disruption events (DTDEs) with SMBHBs. With the help of scattering experiments, we find that the time interval between two successive tidal disruption events (TDEs) depend on the semimajor axis of incident stellar binaries. For stellar binaries with 1 M⊙ for each companion star and a semimajor axis less than 100 au, the maximum time interval is about 150 days when the stellar binary is tidally disrupted by an SMBH. However, for an SMBHB, the time intervals can be very large, and the maximum can exceed 10,000 years. Moreover, we also compare the probabilities of a DTDE with the time interval larger than 150 days by the SMBHB and of two separate TDEs by the SMBH with the same time interval. We find that, for the time interval of 150 days to 15 years, the probability of DTDEs by the SMBHB with a large mass ratio (i.e., qbhb ≳ 0.1) is larger than that of the SMBH scenario. Finally, according to our results, we suggest that DTDEs with the time interval of 150 days to 15 years could be useful tools for finding SMBHB candidates with the mass ratio qbhb ≳ 0.1 at galactic centers. [ABSTRACT FROM AUTHOR]

We present new stringent limits on the mass M• of the central supermassive black hole for a sample of seven nearby galaxies. Our M• estimates are based on the dynamic modeling of the central width of the nebular emission lines measured over sub-arcsecond apertures with the Hubble Space Telescope. The central stellar velocity dispersion, σc, of the sample galaxies is derived from new long-slit spectra from ground-based observations and the bulge effective radius is obtained from a two-dimensional photometric decomposition of the i-band images from the Sloan Digital Sky Survey. The derived stringent M• limits run parallel and above the M•− σc relation, with no systematic trend depending on the galaxy distance or morphology. This gives further support to previous findings suggesting that the nuclear gravitational potential is remarkably well traced by the width of the nebular lines when the gas is centrally peaked. With our investigation, the number of galaxies with stringent M• limits obtained from the nebular line width increases to 114 and can be used for studying the scaling relations between M• and properties of their host galaxies. [ABSTRACT FROM AUTHOR]

We briefly review how X-ray observations of high-redshift active galactic nuclei (AGNs) at z=4-7 have played a critical role in understanding their basic demographics as well as their physical processes; for example, absorption by nuclear material and winds, accretion rates, and jet emission. We point out some key remaining areas of uncertainty, highlighting where further Chandra and XMM-Newton observations/ analyses, combined with new multiwavelength survey data, can advance understanding over the next decade. [ABSTRACT FROM AUTHOR]

Supermassive black hole (SMBH) accretion is an important topic of astro-physical research for a variety of fields. However, literature shows that precisely modelling the X-ray reflection component of an accretion disk around a SMBH is challenging. We test how reliably we can measure key active galactic nuclei (AGN) X-ray reflection parameters by simulating the spectra of average Seyfert 1 galaxies and then fitting those spectra using common modelling techniques. The AGN spectra were created from 0.01-300.0 keV using XMM- Newton pn responses and with (3.75±0.10)×106 counts in the 2-10 keV band. The model RELXILL was used to create all spectra with a reflection fraction (ratio of reflected flux over primary flux from 0.1-100 keV) of R = 1. The values of six key parameters were generated randomly within given ranges to simulate the spectra: photon index (Γ), inner emissivity index ( q 1), black hole spin ( a), disk inclination angle (θ), ionization (ξ), and iron abundance in solar units ( A Fe). Once the simulated spectra were created, they were autonomously fit with RELXILL from 2.5-10.0 keV. All six key parameters were allowed to vary throughout the modelling process, with a gradual thawing of model parameters to mimic manual fitting procedure. We find that we can successfully measure key AGN spectral components in this scenario, but some conditions apply: Γ, θ, and A Fe are well constrained, however they are also consistently overestimated. Only black hole spin ( a) measurements that are in extrema, a > 0.9, can be considered reliable. Lastly, ξ and q 1 cannot be measured and these parameters - along with intermediate spin values - should be verified using other techniques. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

NGC 1365 hosts an X-ray obscured AGN known for both its variable absorption and its relativistic features in the reflection component. Recent simultaneous observations performed by XMM- Newton and NuSTAR caught the source in a rare, nearly unobscured state, revealing the presence of a warm absorber and a neutral, but low column density (∼ 1022 cm-2) absorber, usually not observable due to thicker layers along the line of sight. Here I propose a multi-layer structure of the circumnuclear medium which can explain all the observed absorption states of this source, and their variability properties. Remarkably, despite the spectral complexity due to this multi-component absorber, the relativistic reflection component (and hence the black hole spin) can be unambiguously measured through a time resolved spectroscopic analysis. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Variable X-ray absorption has been observed in active galactic nuclei (AGN) on several time scales. Observations allow us to identify the absorber with clouds associated either with the clumpy torus (parsec scales, long timescales) or with the broad line region (BLR) (short timescales). In the latter, the cloud size has been estimated to be of the order of few gravitational radii from the observed absorption variability. Such small cloud sizes are comparable to the X-ray emitting regions so that a detailed modeling of occultation events in AGN has the potential of enabling us to infer accurately the geometry of the system. We have developed a relativistic X-ray spectral model for occultation events and we present here theoretical predictions on the different observables that can be inferred by studying X-ray eclipses in simulated XMM Newton data. These include the size of the X-ray emitting regions as well as more fundamental parameters such as the black hole spin and the system inclination. We find that absorption varies as a function of the energy range and that its maximum takes place when the approaching part of the accretion disc is covered. Therefore we study the hard-to-soft (H/ S) ratio light curves produced during an eclipse and use them to characterise the properties of the inner accretion disc in a new model-independent way. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We present a detailed analysis of a recent 500 ks net exposure Suzaku observation, carried out in 2013, of the nearby ( z = 0.184) luminous ( Lbol ∼ 1047 erg s-1) quasar PDS 456 in which the X-ray flux was unusually low. The short term X-ray spectral variability has been interpreted in terms of variable absorption and/or intrinsic continuum changes. In the former scenario, the spectral variability is due to variable covering factors of two regions of partially covering absorbers. We find that these absorbers are characterised by an outflow velocity comparable to that of the highly ionised wind, i.e. ∼ 0.25 c, at the 99.9% (3.26σ) confidence level. This suggests that the partially absorbing clouds may be the denser clumpy part of the inhomogeneous wind. Following an obscuration event we obtained a direct estimate of the size of the X-ray emitting region, to be not larger than 20 Rg in PDS 456. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

One of the open problems for AGN is the nature of the primary X-ray emission: It is likely due to Comptonization of soft UV photons, but the optical depth and temperature of the emitting corona were largely unknown before the launch of the Nuclear Spectroscopic Telescope Array (NuSTAR). It is the first focusing hard X-ray telescope on orbit, ∼ 100 times more sensitive in the 10-79 keV band compared to previous observatories, enabling the study of AGN at high energies with high precision. We present and discuss the results on the hot corona parameters of active galactic nuclei that have been recently measured with NuSTAR (often in coordination with XMM- Newton, Suzaku, or Swift) with unprecedented accuracy, in a number of local Seyfert galaxies. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

X-ray reverberation, where light-travel time delays map out the compact geometry around the inner accretion flow in supermassive black holes, has been discovered in several of the brightest, most variable and well-known bare Seyfert galaxies. In this work, we expand the study of X-ray time lags to all Seyfert galaxies in the XMM- Newton archive above a nominal rms and exposure level. We find that reverberation is found in >50 % of sources (with >99 % confidence). We also find that the low-frequency hard lag (which is likely associated with the coronal emission) is found in >80% of sources, suggesting that most sources with X-ray variability show intrinsic variability from the nuclear region. We update the known iron K lag amplitude vs. black hole mass relation. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The 'broad iron spectral features' are often seen in X-ray spectra of active galactic nuclei (AGN) and black-hole binaries (BHB). These features may be explained either by the 'relativistic disc reflection' scenario or the 'partial covering' scenario: It is hardly possible to determine which model is valid from time-averaged spectral analysis. Thus, X-ray spectral variability has been investigated to constrain spectral models. To that end, it is crucial to study iron structure of BHBs in detail at short time-scales, which is, for the first time, made possible with the Parallel-sum clocking (P-sum) mode of XIS detectors on board of Suzaku. This observational mode has a time-resolution of 7.8 ms as well as a CCD energyresolution. We have carried out systematic calibration of the P-sum mode, and investigated spectral variability of the BHB GRS 1915+105. Consequently, we found that the spectral variability of GRS 1915+105 does not show iron features at sub-seconds. This is totally different from variability of AGN such as 1H0707-495, where the variation amplitude significantly drops at the iron K-energy band. This difference can be naturally explained in the framework of the 'partial covering' scenario. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The origin of short timescale (weeks/months) variability of AGN, whether due to intrinsic disc variations or reprocessing of X-ray emission by a surrounding accretion disc, has been a puzzle for many years. However recently a number of observational programmes, particularly of NGC 5548 with Swift, have shown that the UV/optical variations lag behind the X-ray variations in a manner strongly supportive of X-ray reprocessing. Somewhat surprisingly, the implied size of the accretion disc is ∼3 times greater than expected from a standard, smooth, Shakura-Sunyaev thin disc model. Although the difference may be explained by a clumpy accretion disc, it is not clear whether the difference will occur in all AGN or whether it may change as, eg, a function of black hole mass, accretion rate, or disc temperature. Measurements of interband lags for most AGN require long timescale monitoring, which is hard to arrange. However for low mass (<106 M⊙) AGN, the combination of XMM- Newton EPIC (X-rays) with the optical monitor in fast readout mode allows an X-ray/UV-optical lag to be measured within a single long observation. Here we summarise previous related observations and report on XMM- Newton observations of NGC 4395 (mass 100 times lower, accretion rate ∼20 times lower than for NGC 5548). We find that the UVW1 lags the X-rays by ∼470 s. Simultaneous observations at 6 different ground based observatories also allowed the g-band lag (∼800 s) to be measured. These observations are in agreement with X-ray reprocessing but initial analysis suggests that, for NGC 4395, they do not differ markedly from the predictions of the standard thin disc model. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The GHz-Peaked Spectrum (GPS) quasar OQ172 (J1445+0958) has an extremely high rest-frame rotation measure (RM > 20000 rad m-2) and an RM gradient in its inner nucleus. Its jet observed with Very Long Baseline Interferometry (VLBI) is strongly bent along an arc spanning > 100 pc. Near infrared (NIR) spectra reveal an unusually large [O III] line width which suggests a large mass within the NLR and/or strong interactions between the emerging jet and the dense material therein. We present our VLBI Space Observatory Programme (VSOP) and Multi-frequency Very Long Baseline Array (VLBA) observation of the GPS quasar OQ172. The observations will help us to explore the VLBI radio properties and to better understand the circumnuclear environment of OQ172. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Are the FRI and FRII radio galaxies representative of the radio-loud (RL) AGN population in the local Universe? Recent studies on the local low-luminosity radio sources cast lights on an emerging population of compact radio galaxies which lack extended radio emission. In a pilot JVLA project, we study the high-resolution images of a small but representative sample of this population. The radio maps reveal compact unresolved or slightly resolved radio structures on a scale of 1-3 kpc. We find that these RL AGN live in red massive early-type galaxies, with large black hole masses (≳108 M⊙), and spectroscopically classified as Low Excitation Galaxies, all characteristics typical of FRI radio galaxies which they also share the same nuclear luminosity with. However, they are more core dominated (by a factor of ∼30) than FRIs and show a clear deficit of extended radio emission. We call these sources 'FR0' to emphasize their lack of prominent extended radio emission. A posteriori, other compact radio sources found in the literature fulfill the requirements for a FR0 classification. Hence, the emerging FR0 population appears to be the dominant radio class of the local Universe. Considering their properties we speculate on their possible origins and the possible cosmological scenarios they imply. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We analyze the X-ray properties of the Compton-thick Seyfert 1.9 radio quiet AGN in NGC 1194 using INTEGRAL (ISGRI), XMM- Newton (EPIC), Swift (BAT and XRT), and Suzaku (XIS) observations. There is a set of Fe-K lines in the NGC 1194 spectrum with complex relativistic profiles that can be considered as a sign of either a warped Bardeen-Petterson accretion disk or double black hole. We compare our results on NGC 1194 with two other megamaser warped disk candidates, NGC 1068 and NGC 4258, to trace out the other properties which can be typical for AGNs with warped accretion disks. To finally confirm or disprove the double black-hole hypotheses, further observations of the iron lines and their evolution of their shape with time are necessary. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We review the current state of understanding how accretion onto a black hole proceeds and what the key elements needed to form relativistic jets are. Theoretical progress is severely undermined by the lack of thorough understanding of the microphysics involved in accretion discs and in the formation of jets, particularly in the presence of strong magnetic fields. Therefore, all proposed solutions are still models that need to be validated by observational constraints. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We present neutral hydrogen (H I) and warm molecular hydrogen (H2) observations of the young (102 yr) radio galaxy PKS B1718-649. We study the morphology and the kinematics of both gas components, focusing, in particular, on their properties in relation to the triggering of the radio activity. The regular kinematics of the large scale H i disk, seen in emission, suggests that an interaction event occurred too long ago to be responsible for the recent triggering of the radio activity. In absorption, we detect two absorption lines along the narrow line of sight of the compact ( r < 2 pc) radio source. The lines trace two clouds with opposite radial motions. These may represent a population of clouds in the very inner regions of the galaxy, which may be involved in triggering the radio activity. The warm molecular hydrogen (H2 1-0 S(1) ro-vibrational line) in the innermost kilo-parsec of the galaxy appears to be distributed in a circum-nuclear disk following the regular kinematics of the H I and of the stellar component. An exception to this behaviour arises only in the very centre, where a highly dispersed component is detected. These particular H I and H2 features suggest that a strong interplay between the radio source and the surrounding ISM is ongoing. The physical properties of the cold gas in the proximity of the radio source may regulate the accretion recently triggered in this AGN. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

At present neutral atomic hydrogen (H I) gas in galaxies at redshifts above z ∼ 0.3 (the extent of 21 cm emission surveys in individual galaxies) and below z ∼ 1.7 (where the Lyman- α line is not observable with ground-based telescopes) has remained largely unexplored. The advent of precursor telescopes to the Square Kilometre Array will allow us to conduct the first systematic radio-selected 21 cm absorption surveys for H I over these redshifts. While H I absorption is a tracer of the reservoir of cold neutral gas in galaxies available for star formation, it can also be used to reveal the extreme kinematics associated with jet-driven neutral outflows in radio-loud active galactic nuclei. Using the six-antenna Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder, we have demonstrated that in a single frequency tuning we can detect H I absorption over a broad range of redshifts between z = 0.4 and 1.0. As part of our early science and commissioning program, we are now carrying out a search for absorption towards a sample of the brightest GPS and CSS sources in the southern sky. These intrinsically compact sources present us with an opportunity to study the circumnuclear region of recently re-started radio galaxies, in some cases showing direct evidence of mechanical feedback through jetdriven outflows. With the sensitivity of the full ASKAP array we will be able to study the kinematics of atomic gas in a few thousand radio galaxies, testing models of radio jet feedback well beyond the nearby Universe. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Magnetic fields in an accretion disk around the central black hole can modify the size of the innermost stable circular orbit (ISCO) and can produce a difference to the classical Novikov-Thorne radius. We estimated the ISCO magnetic field strength from the polarimetric observations of the accretion-disk radiation. This estimate is obtained taking into account the effect of the Faraday rotation of the polarization plane at the distance of the mean free path of photons between successive electron scattering events. We present the new method for estimating the ISCO radius in the accretion disk, i.e. in the nearest vicinity of a central black hole. Our estimates confirmed the Frolov, Shoom & Tzounis (2014) and Ranea-Sandoval & Garcia (2015) conclusion that the magnetic field in the accretion disk decreases the size of the innermost stable circular orbit. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Motivated by the theoretical and observational evidence that after a major merger of gas-rich galaxies a massive gaseous disk with a SMBH binary will be formed in the nuclear region of the remnant, we study the interaction between an unequal mass binary and an isothermal circumbinary disk. We focus our study in the transport of angular momentum from the binary to the disk and how this transport can result on the formation of a cavity or gap in the gaseous disk. We propose that, for comparable mass binaries, this exchange of angular momentum is driven by the gravitational interaction of the binary and a strong non-axisymmetric density perturbation that is formed in the disk as response to the presence of the gravitational field of the binary. We compare the efficiency of this gravitational torque on extract angular momentum from the binary with the efficiency of redistribution of the extracted angular momentum in the disk to derive a gap-opening criterion. We run a set of SPH simulations of binaries embedded in isothermal gaseous disks to test our gap-opening criterion. We find that our gap-opening criterion successfully predicts in which simulations a gap will form on the disk. We also run simulations of merging galaxies and we apply our criterion to the more real SMBHB-Disk systems that are formed in situ in these simulations. We find that, in the conditions of our galaxy mergers simulations, the formation of a circumbinary gap is unlikely. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We analyzed the spectra collected under the wide-field nearby galaxy clusters survey (WINGS) to reveal emission lines in cluster galaxies. After removing stellar emission with dedicated population synthesis models we found evidence of faint emission line activity in a sizable number of sources. Diagnostic diagrams were used to define or at least constrain the origin of the emission line activity. Cross-correlation with radio surveys is also being used for the identification of 'true' active nuclei. We report the discovery of a previously unknown Seyfert 1 nucleus, WINGS J230945.81+072431.0, and preliminary results on prevalence and basic properties of the active and star forming galaxies we identified. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We show that for the accretion disk with equipartition between magnetic and radiative pressures, prograde black holes generate outflowing energy in jets more efficiently than retrograde black holes do. Both viscous radiative and irradiative disks provide more efficient outflow jets in the case of a prograde black hole than in the case of a retrograde black hole. Our results confirm the conclusion of Tchekhovskoy & McKinney (2012) that, for the same absolute value of the spin, prograde black holes with geometrically thick accretion disks generate outflows several times more efficiently than retrograde black holes do. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]