The 3.5 meter diameter Herschel Space Observatory conducted a ∼720 square-degree survey of the Galactic plane, the Herschel Galactic plane survey (Hi-GAL). These data provide the most sensitive and highest resolution observations of the far-IR to sub-mm continuum from the central molecular zone (CMZ) at λ = 70, 160, 250, 350, and 500 μm obtained to date. Hi-GAL can be used to map the distributions of temperature and column density of dust in CMZ clouds, warm dust in Hii regions, and identify highly embedded massive protostars and clusters and the dusty shells ejected by supergiant stars. These data enable classification of sources and re-evaluation of the current and recent star-formation rate in the CMZ. The outer CMZ beyond |l| = 0.9 degrees (Rgal > 130 pc) contains most of the dense (n > 104 cm−3 gas in the Galaxy but supports very little star formation. The Hi-GAL and Spitzer data show that almost all star formation occurs in clouds moving on x2 orbits at Rgal < 100 pc. While the 106 M⊙ Sgr B2 complex, the 50 km s−1 cloud near Sgr A, and the Sgr C region are forming clusters of massive stars, other clouds are relatively inactive star formers, despite their high densities, large masses, and compact sizes. The asymmetric distribution of dense gas about Sgr A* on degree scales (most dense CMZ gas and dust is at positive Galactic longitudes and positive VLSR) and compact 24 μm sources (most are at negative longitudes) may indicate that eposidic mini-starbursts occasionally ‘blow-out’ a portion of the gas on these x2 orbits. The resulting massive-star feedback may fuel the compact 30 pc scale Galactic center bubble associated with the Arches and Quintuplet clusters, the several hundred pc scale Sofue-Handa lobe, and the kpc-scale Fermi/LAT bubble, making it the largest ‘superbubble’ in the Galaxy. A consequence of this model is that in our Galaxy, instead of the supermassive black hole (SMBH) limiting star formation, star formation may limit the growth of the SMBH.

The Australia Telescope Large Area Survey (ATLAS) is the widest deep radio survey ever attempted, covering ~7deg2 across its two fields, the Chandra Deep Field South (CDFS) and the European Large Area ISO Survey South 1 Region (ELAIS-S1). ATLAS has extensive multiwavelength data, including optical, infrared and X-ray, to complement its ~15μJy rms 1.4 GHz radio data. At these faint radio flux densities, the proportion of AGN to star-forming galaxies (SFGs) is high, and there are likely many composite objects, which have both an AGN and ongoing star formation. In ATLAS, we estimate that the number of AGN is approximately 50%, and this proportion will change with decreasing flux density. To understand the relationship between the AGN and the host galaxy, we need to measure the contribution of the AGN to the total luminosity, and determine how this varies with the evolutionary stage of the galaxy. Here I present results exploring the AGN contribution to galaxies over cosmic time, through the use of different multiwavelength discriminants.

The origin of the Galactic center diffuse X-ray emission (GCDX) is still under intense investigation. We have found a clear excess in a longitudinal GCDX profile over a stellar number density profile in the nuclear bulge region, suggesting a significant contribution of diffuse, interstellar hot plasma to the GCDX. We have estimated that contributions of an old stellar population to the GCDX are ∼50% and ∼20% in the nuclear stellar disk and nuclear star cluster, respectively. Our near-infrared polarimetric observations show that the GCDX region is permeated by a large scale, toroidal magnetic field. Together with observed magnetic field strengths in nearly energy equipartition, the interstellar hot plasma could be confined by the toroidal magnetic field.

We have been monitoring the flux density of Sagittarius A* (Sgr A*) at 22 GHz since DOY=42 (11 Feb. 2013) with a sub-array of the Japanese VLBI Network in order to search the increase of 22-GHz emission from Sgr A* induced by the interaction of the G2 cloud with the accretion disk. The flux densities observed until DOY=322 (18 Nov. 2013) are consistent with the previously observed values before the approaching of the cloud. We have detected no large flare during this period.

Recently the gas and dust cloud “G2” was discovered on a highly eccentric orbit around the massive black hole in the Galactic center. The orbit will bring the cloud as close as 2400 Schwarzschild radii to Sgr A* beginning of 2014. With the help of hydrodynamical simulations using the PLUTO code, we investigate possible origins and the fate of the cloud in the coming years. In this proceedings article, we concentrate on a scenario where G2 is interpreted as a diffuse gas cloud and show its detailed evolution in the observable position-velocity diagrams. We further elaborate on the problem of the tail emission which might or might not be related to the G2 cloud.

New estimates of the interband lags between variations in the B band and variations in the V, R, and I bands for three active galactic nuclei (AGNs) are present. In contrast to the previous study by Sergeev et al. (2005), the effect of the contribution of the broad lines to the bands is taken into account.

Integral field spectroscopy provides us with immensely rich datasets about spatially resolved distributions and kinematics of emission and absorption lines. In this contribution I will describe some of the key insights that have been made about AGN using optical, near infrared, and far infrared IFUs. These encompass gas inflow and outflow mechanisms, and the relations between star formation, the torus, and accretion onto the black hole. Progress so far has largely relied on archetypal and small sets of objects. In the future, a more statistically robust approach will be required. I will end by discussing a number of issues that can easily confuse an emerging picture, and need to be borne in mind for such surveys.

With the goal of investigating the link between black hole (BH) and star formation (SF) activity, we study a deep sample of radio selected star forming galaxies (SFGs) and active galactic nuclei (AGNs). Using a multi-wavelength approach we characterize their host galaxies properties (stellar masses, optical colors, and morphology). Moreover, comparing the star formation rate derived from the radio and far-infrared luminosity, we found evidences that the main contribution to the radio emission in the radio-quiet AGNs is star-formation activity in their host galaxy.

Using 192 composite spectra stacked from subsamples of individual SDSS quasar spectra binned in spectral index, αλ, and logarithm of monochromatic luminosity at 1450 Å, log l1450, and modelling separate spectral ranges with superposition of emission lines it was found that: there is a dependence of emission line equivalent width (EW) on αλ (correlation or anti-correlation) for some lines, mostly for those lines for which the Baldwin effect is detected, while for the lines for which the Baldwin effect is not observed any αλ-dependence was found.

The Joint Catalogue of Hamburg ROSAT Sources (HRC/BHRC) is the result of merging of HRC and BHRC catalogs built on the basis of optical identifications of ROSAT BSC and ROSAT FSC. Altogether, 8132 sources are present. Based on this catalogue, we have compiled a sample of ROSAT AGN, including candidate ones. In this paper we classify candidate AGN (those that previously had not been spectroscopically classified) by their activity type. The sample contains 955 objects with count rate of photons CR>0.04 ct/s in the area with galactic latitudes |b|>30 and declinations δ>0, however only 217 objects have SDSS DR10 spectra. The classification led to the following results: 95 AGN, 71 absorption-line galaxies, 42 stars, and 9 unclassified objects.

High-redshift quasars are unique probes of the evolution of supermassive black holes and the intergalactic medium at the end of the epoch of reionization. We present the optical spectra of eight new z ~ 6 quasars selected from the Panoramic Survey Telescope & Rapid Response System 1 (Pan-STARRS1). Details of the selection strategy can be found in Bañados et al. (2014). With this work we increase the number of known quasars at z < 5.7 by more than 10%. The quasars discovered here span a large range of luminosities (19.6 ≤ zP1 ≤ 21.2) and are remarkably heterogeneous in their spectral features: half of them show bright emission lines whereas the other half show weak or no Lyα emission line. We find a larger fraction of weak–line emission quasars than in lower redshift studies, although still based on low number statistics, this may imply that the quasar population could be more diverse than previously thought.

A large fraction of the AGN output power is emitted in the X-rays, in a region very close to the supermassive black hole (SMBH). The most distinctive feature of the X-ray spectra of AGN is the iron Kα line, often observed as the superposition of a broad and a narrow component. While the broad component is found in only ~ 35–45% of bright nearby AGN, the narrow component has been found to be ubiquitous. The narrow Fe Kα line is thought to be produced in the circumnuclear material, likely in the molecular torus. Given its origin, this feature is possibly the most important tracer of neutral matter surrounding the SMBH. One of the most interesting characteristics of the narrow Fe Kα line is the decrease of its equivalent width with the continuum luminosity, the so-called X-ray Baldwin effect (Iwasawa & Taniguchi 1993). This trend has been found by many studies of large samples of type-I AGN, and very recently also in type-II AGN (Ricci et al. 2013c, submitted to ApJ). The slope of the X-ray Baldwin effect in type-II AGN is the same of their unobscured counterparts, which implies that the mechanism at work is the same. Several hypothesis have been put forward in the last decade to explain the X-ray Baldwin effect: i) a luminosity-dependent variation in the ionisation state of the iron-emitting material (Nandra et al. 1997); ii) the decrease of the number of continuum photons in the iron line region with the Eddington ratio, as an effect of the well known correlation between the photon index and the Eddington ratio (Ricci et al. 2013b, submitted to MNRAS); iii) the decrease of the covering factor of the torus with the luminosity (e.g., Page et al. 2004, Ricci et al. 2013a A&A 553, 29) as expected by luminosity-dependent unification models (e.g., Ueda et al. 2003). In my talk I will review the main characteristics of the narrow Fe K? line, and present the results of our recent works aimed at explaining the X-ray Baldwin effect using iron-line emitting physical torus models (Ricci et al. 2013a, b), and at understanding the origin of the Fe K? line (Ricci et al. 2013c). I will focus in particular on the importance of the Fe Kα line as a probe of the evolution of the physical characteristics of the molecular torus with the luminosity.

We present results from a project focused on searching optical microvariabilty (also known as “intra-night” variability) in type 2 - obscured - quasars. Optical microvariability can be described as very small changes in the flux, typically in the order of hundredths of magnitude, which can be observed on timescales of hours. Such studies have been so far conducted for samples of blazars and type 1, unobscured, AGNs, where the optical microvariability was detected with success. We have focused on obscured targets which would pose a challenge to the AGN standard model. In the present work, however, we have observed a sample of three bright (g mag < 17) type 2 quasar, based on the catalog of type 2 quasars from SDSS of Reyes et al. (2008). The observations were carried out with the 1.5 meter telescope at San Pedro Martir observatory in Mexico. The sample was observed during an observation period of four days in Johnsons V filter, resulting in at least two continuous intervals of observations per target during the observational run. We have obtained differential light curves for our sources as well as for the comparison stars. They were analyzed using one-way analysis of variance statistical test (ANOVA), which has been repeatedly used in the past for studies of unobscured targets. Based on the results from the statistical analysis, we show that at least two out of three observed targets appear to be variable on time scales of hours. So far, this is the first study which confirmed existence of optical microvariability in type 2 quasars.

Very long baseline interferometry observations at millimeter wavelengths have detected source structure in Sgr A* on event horizon scales. Near-infrared interferometry will achieve similar resolution in the next few years. These experiments provide an unprecedented opportunity to explore strong gravity around black holes, but interpreting the data requires physical modeling. I discuss the calculation of images, spectra, and light curves from relativistic MHD simulations of black hole accretion. The models provide an excellent description of current observations, and predict that we may be on the verge of detecting a black hole shadow, which would constitute the first direct evidence for the existence of black holes.

Runaway instability operates in accretion tori around black holes, where it affects systems close to the critical (cusp overflowing) configuration. The runaway effect depends on the radial profile l(R) of the angular momentum distribution of the fluid, on the dimension-less spin a of the central black hole (|a| ≤ 1), and other factors, such as self-gravity. Here we discuss the role of runaway instability within a framework of an axially symmetric model of perfect fluid endowed with a purely toroidal magnetic field.

Several supernovae exploding in a compact cluster of massive stars generate a galactic outflow with embedded shock waves. Based on numerical simulations for an expanding superbubble above the Galactic center we find that these individual waves generated by the repeated SN-explosions, interact with each other and finally coalesce into a single strong shock at a distance of 5 kpc above the Galactic plane at about 5 ċ 106 years after outbreak. The resulting shock with a Mach number M ≃ 10 propagates up to 100 kpc in less than 108 years. The time-dependent mass an energy loss out of the superbubble affects the further evolution of the outflow. In such long lasting shock waves energetic particles can be accelerated above the knee of 1015 eV already near the galactic plane by a first-order Fermi-mechanism. The additional pressure gradients from such cosmic rays lead to further accelerations of the galactic outflow since these ultra-relativistic particles suffer less from adiabatic losses than the thermal gas.

The intriguing existence of ‘True’-Seyfert 2s has opened a debate on the validity of the unified model of active galactic nuclei (AGN). These objects, also called ‘Naked’-AGN, seem to lack a broad line region. In some cases, their X-ray emission is unabsorbed, typical of Seyfert 1 galaxies, indicating a clear view toward the nucleus, but no broad lines are seen in the optical. In ‘True’-Seyfert 2s with higher column densities, observations of polarized light have failed to reveal the hidden broad emission. We performed high-resolution near-infrared integral-field observations of two ‘True’-Seyfert 2 candidates: IRAS 01072+4954 and NGC 7496. We found that the AGN in these sources might power very faint and narrow broad emission lines (FWHMbroad < 1500km s−1). Here, we discuss the properties of the broad components estimated from published X-ray and/or optical measurements and present their near-infrared candidate identification. Both galaxies host intermediate-mass black holes, with masses ~ 105−106 M⊙. Our results favor the unified model in the cases of high accretion rates, and stress the necessity of a multiwavelength approach to unveil the nature of ‘Naked’-AGN.

The supermassive black hole at the Galactic center, Sagittarius A* has experienced periods of higher activity in the past. The reflection of these past outbursts is observed in the molecular material surrounding the black hole but reconstructing its precise lightcurve is difficult since the distribution of the clouds along the line of sight is poorly constrained.

Using Chandra high-resolution data collected from 1999 to 2011 we studied both the 6.4 keV and the 4–8 keV emission of the region located between Sgr A* and the Radio arc, characterizing its variations down to 15″ angular scale and 1-year time scale. The emission from the molecular clouds in the region varies significantly, showing either a 2-year peaked emission or 10-year linear variations. This is the first time that such fast variations are measured. Based on the cloud parameters, we conclude that these two behaviors are likely due to two distinct past outbursts of Sgr A* during which its luminosity rose to at least 1039 erg s−1.

It was used the date of more than 650 extragalactic radio sources for the study of distribution of spectral indexes and elongation for the radio sources of different Fanaroff Riley (FR) classes. It was shown, that no large differences are observed in the distribution of spectral indexes in radio sources FRI and FRII classes. From the study of distribution of the elongation of extragalactic radio sources it was found the following basic morphological differences for the objects of different FR classes: a) the radio images of extragalactic radio sources FRII type in the average are more elongated than the radio images of extragalactic radio sources FRI type: b) the extragalactic radio sources FRI type can be divided on two subtypes with two function of distribution of the elongation parameter K having different maximums. These two subtypes of radio sources of FRI class, in besides of different average elongation of radio images, probably must have also differences in the orientations of these elongation directions relative to the direction of rotation axes of parent optical galaxies that in most cases are coincide with the minor optical axes of galaxies.