The observed properties of supermassive black holes suggest a fundamental link between their assembly and the formation of their host spheroids. We model the growth and activity of black holes in galaxies using ΛCDM cosmological hydrodynamic simulations. We study the evolution of the metal enrichment in quasar hosts and hence explore the relationship between star/spheroid formation and black hole growth/activity in galaxies. Using the simulations we approach the epoch of the first quasars and the first significant star formation activity. We show that the hosts of the rare bright quasars at z∼5−6 have star formation rates of several hundred $\rm\thinspace M_{\odot}\yr^{-1},$ and halo masses of order ∼1012$\rm\thinspace M_{\odot}$. Already at these redshifts they have supersolar ($Z/Z_{\odot} \sim 2-3$) central metallicities, with a mild dependence of metallicity on luminosity, consistent with observed trends.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In order to analyse the large numbers of Seyfert galaxy spectra available at present, we are testing new techniques to derive their physical parameters fastly and accurately.

We present an experiment on such a new technique to segregate old and young stellar populations in galactic spectra using machine learning methods. We used an ensemble of classifiers, each classifier in the ensemble specializes in young or old populations and was trained with locally weighted regression and tested using ten-fold cross-validation. Since the relevant information concentrates in certain regions of the spectra we used the method of sequential floating backward selection offline for feature selection.

Very interestingly, the application to Seyfert galaxies proved that this technique is very insensitive to the dilution by the Active Galactic Nucleus (AGN) continuum. Comparing with exhaustive search we concluded that both methods are similar in terms of accuracy but the machine learning method is faster by about two orders of magnitude.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I briefly report on the work conducted to probe the gravitational potential of active and non-active disk galaxies using gas and stellar kinematics.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present our recent results from the observation of the O VI λ λ1032,1038 emission doublet in Seyfert galaxies of type 2 with the FUV spectrograph on the FUSE satellite. These observations are part of our investigation to contrast the properties of the OVI emission line and the absorbing outflows in a sample of rigorously matched Seyfert 1s and 2s, in the framework of the Unified Scheme. The OVI emission line is an excellent diagnostic of the outflowing hot gas at temperatures of ∼106K. In the Unified Scheme, Seyferts of type 2 are those whose central regions are obscured by the ubiquitous dusty torus. We interpret our results in this framework.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

As part of a larger program to study spatially resolved jet / interstellar medium interactions in nearby Seyfert galaxies, we have obtained high spatial resolution spectrographic observations of the central regions of M 51 and its extra-nuclear cloud (XNC, Ford et al. 1985), using STIS on-board the Hubble Space Telescope (HST). In this paper, we present very preliminary results from these observations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present an overview on the state of the gas in cluster outskirts. We show that the entropy of the gas in the outskirts often exhibit strong deviations from predictions based on the cluster scaling. We identify the cause of these deviations with incomplete shock propagation observed in clusters with ongoing major merging, survival of substructure and incomplete thermalization, and emission from the surrounding large-scale structure seen in projection.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have studied the quantitative morphology of the galaxies of the Coma cluster brighter than $m_{r}=17$. The surface brightness profiles of all galaxies were decomposed into the structural components: bulge and disc. We found a correlation between the scale length of the discs and the location in the cluster. Galaxies located at small projected distances show smaller discs than those located in the outermost regions of the cluster. We have also investigated the correlation betwenn the B$-$r color of the galaxies and their environment. For late-type galaxies there is a correlation between the color and the position in the cluster. The bluest galaxies are located in the outermost regions of the cluster and show the largest discs. These results can be explained in terms of galaxy harassment.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present single-dish observations of a sample of 27 nearby (z<0.018) Seyfert galaxies obtained with the ATNF/Mopra radiotelescope. The total neutral gas content for the sample is derived. We find that Seyfert galaxies are gas-rich objects with a median HI mass to blue luminosity ratio $M_{HI}/L_B\sim 0.38$ M$_\odot$/$L_\odot$, which tends to increase with decreasing optical and far-infrared luminosities. We have also found a correlation among the neutral hydrogen content of Seyfert 2 galaxies and the IRAS luminosities, similar to those found for normal spiral and starburst galaxies. Our results suggest a scenario where the star formation of Seyfert galaxies is similar to that found in starbursts, and that they are dependent of the initial neutral mass content of progenitors of galaxy disks in the blue compact-HII galaxy-Seyfert sequence. Within this sequence, the far-infrared luminosity and the total hydrogen mass correlate as $L_{fir}/L_\odot\propto (M_{HI}/M_\odot)^{1.5\pm 0.4}$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

NGC 1241 is a Sy 2 galaxy with a 1.4 kpc circumnuclear ring (CNR) of star formation revealed in Paα. A 0.3 kpc long Paα emitting bar centered on the nucleus is present, apparently without associated absorption features. GEMINI (+QUIRC+Hokupa) IR pixel-photometry reveals instead an azimuthally symmetric (J−Ks) color which is redder at the nucleus than at the CNR. This property may well be due to the increasing importance of dust when going from the ring inward into the nucleus. Nevertheless the (V−H) color does not indicate special absorption conditions in the nucleus with respect to the CNR, and no absorption features are evident, as normally expected near emitting bars. Then, we propose as an alternative explanation an excess of C-stars in the nuclear region which decreases outwards until reaching the CNR and its colors. We have compared the pixel color-magnitude diagram with the 2-MASS (J−Ks) vs. Ks diagram for the Large Magellanic Cloud: about 5×102 C-stars and 2.5×104 AGB Oxygen-rich stars inside r∼50 pc, are enough to reproduce the observed nuclear tip in the diagram. This stars would release gas that, gravitationally bounded, pollutes the nuclear environment and could amount 10−2 to 10−1 M$_{\odot}$ yr−1 of fuel for the central engine during the lifetime of stars with masses 2 M$_{\odot}\lt M_{CStars} \lt 6{\rm M}_{\odot}$. This scenario may also explain the observed increased strength of the CN-bands in the stellar populations of Sy 2 nuclei, and the recent claim of a significant contribution of intermediate age stars to the optical continuum of low luminosity AGNs.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We discuss the mass assembly history both on cluster and galaxy scales and their impact on galaxy evolution.

On cluster scale, we introduce our on-going PISCES project on Subaru, which plans to target $\sim 15$ clusters at $0.4\le z\le 1.3$ using the unique wide-field ($30'$) optical camera Suprime-Cam and the spectrograph both in optical (FOCAS, $6'$) and near-infrared (FMOS, $30'$). The main objectives of this project are twofold: (1) Mapping out the large scale structures in and around the clusters on 10–14~Mpc scale to study the hierarchical growth of clusters through assembly of surrounding groups. (2) Investigating the environmental variation of galaxy properties along the structures to study the origin of the morphology-density and star formation-density relations. Some initial results are presented.

On galactic scale, we first present the stellar mass growth of cluster galaxies out to $z\sim1.5$ based on the near-infrared imaging of distant clusters and show that the mass assembly process of galaxies is largely completed by $z\sim1.5$ and is faster than the current semi-analytic models' predictions. We then focus on the faint end of the luminosity function at $z\sim1$ based on the Subaru/XMM-Newton Deep Survey imaging data. We show the deficit of red galaxies below $M^*+2$ or 10$^{10}\,{\rm M}_{\odot}$, which suggest less massive galaxies are either genuinely young or still vigorously forming stars in sharp contrast to the massive galaxies where mass is assembled and star formation is terminated long time ago.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A new cosmological multidimensional hydrodynamic and N-body code based on an Adaptive Mesh Refinement scheme is described and tested. The hydro part is based on modern high-resolution shock-capturing techniques, whereas N-body approach is based on a Particle Mesh method. The code has been specifically designed for cosmological applications.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Abundances in Galactic globular clusters are important for understanding Galactic chemical evolution and the formation of the Milk Way. 47 Tucanae (NGC 104) is a template metal-rich globular cluster ([Fe/H] ∼–0.7 dex). From the point of view of high resolution spectroscopy, there is still a lack of abundance analyses in the literature. In this work we present a detailed analysis carried out for 5 giants stars (12.10 < V < 14.30) of 47 Tucanae, using high resolution spectra (λ/Δλ∼60,000) with high signal-to-noise ratio (S/N > 200), obtained at the ESO VLT-UT2 8m telescope, equipped with the UVES spectrograph. Abundances of α- (O, Mg, Ca, Si, Ti), s- (Ba, Y, Sr) and r- (Eu) process elements are obtained.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Studies in optical starlight have failed to reach a consensus on the importance of either galaxy interactions, bars, or nuclear spirals in triggering luminous active galactic nuclei (AGNs). Here, we present the first systematic imaging study of Seyfert (disk) galaxies in the 21-cm line of neutral atomic hydrogen (HI) gas. HI is the most sensitive and enduring tracer of galaxy interactions, and can reveal tidal features not otherwise visible in optical starlight. Our sample comprises all twenty-eight galaxies in the Véron-Cetty & Véron (1998) catalog with nuclear magnitudes −19 ≥ MB > −23 (including Seyfert, LINER, and HII galaxies) at 0.015 ≤ z ≤ 0.017 in the northern hemisphere, and a matched control sample of twenty-seven inactive galaxies at z≈0.008. We have detected nearly all the galaxies observed, and find a much higher incidence of tidal interactions — usually not seen in optical starlight — among the Seyfert galaxies by comparison with the matched control sample. Those Seyferts with uncertain or no clear tidal features show disturbed HI morphologies and/or kinematics, as well as HI companion galaxies, more frequently than the control sample. Our study suggests that the undisturbed optical appearence of active galaxies may be deceptive, and imply that galaxy-galaxy interactions trigger a significant fraction luminous AGNs at low redshifts. The majority of the Seyfert galaxies in our sample appear to be at a relatively early stage of an encounter rather than late in a merger.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report on some of the recent work that has come from our Hubble Space Telescope programme to find massive black holes in nearby spiral galaxies. Determining black hole masses from gas kinematics in spiral galaxies is difficult, but results have been reported for NGC 4041 and new results are soon to be reported for NGC 1300 and NGC 2748. Complementary programmes are also looking for the presence of nuclear star clusters in our Space Telescope Imaging Spectrograph (STIS) and archival Near-infrared Camera and Multi-Object Spectrometer (NICMOS) images. We are also currently analysing United Kingdom Infrared Telescope (UKIRT) Fast Track Imager (UFTI) near-infrared images to determine the surface brightness profiles for 37 of the galaxies in the sample.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the preliminary results of 235 MHz, 327 MHz and 610 MHz observations of the galaxy cluster A3562 in the core of the Shapley Concentration (SC). The purpose of these observations, carried out with the Giant Metrewave Radio Telescope (GMRT, Pune, India) was to study the radio halo located at the centre of A3562 and determine the shape of its radio spectrum at low frequencies, in order to understand the origin of this source. In the framework of the re–acceleration model, the preliminary analysis of the halo spectrum suggests that we are observing a young source (few $10^8$ yrs) at the beginning of the re–acceleration phase.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In this paper, we revisit the constraints obtained by several authors (Reichart et al. 1999; Eke et al. 1998; Henry 2000) on the estimated values of $\Omega_{\rm m}$, $n$ and $\sigma_8$ in the light of recent theoretical developments: 1) new theoretical mass functions (Sheth & Tormen 1999, Sheth, Mo & Tormen 2001, Del Popolo 2002b); 2) a more accurate mass-temperature relation, also determined for arbitrary $\Omega_{\rm m}$ and $\Omega_{\rm \Lambda}$ (Del Popolo 2002a).

Firstly, using the quoted improvements, we re-derive an expression for the X-ray Luminosity Function (XLF), similarly to Reichart et al. (1999), and then we get some constraints to $\Omega_{\rm m}$ and $n$, by using the ROSAT BCS and EMSS samples and maximum-likelihood analysis. Then we re-derive the X-ray Temperature Function (XTF), similarly to Henry (2000), re-obtaining the constraints on $\Omega_{\rm m}$, $n$, $\sigma_8$. Both in the case of the XLF and XTF, the changes in the mass function and M-T relation produces an increase in $\Omega_{\rm m}$ of $\simeq 20\%$ and similar results in $\sigma_8$ and $n$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We discuss the results so far of a program to image in the rest-frame optical and near-UV the host galaxies of a sample of 5 high redshift (z∼2−3) radio-quiet quasars with nuclear luminosities lower than most samples studied at high z. We found that in the rest-frame optical the hosts have luminosities of about L∗, comparable to the Lyman break galaxies at similar redshifts. From the rest-frame UV imaging, we can derive optical–UV colors, and find they show a great deal of variation, but may be somewhat redder and less starforming than the LBGs. We are supplementing this work at high z with study of the hosts of z∼1 radio-quiet quasars with similar low nuclear luminosities.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In this contribution we investigate the connection between clusters of galaxies and their large-scale environment, with an emphasis on clusters which are well characterized by their X-ray emission. We show that this connection is so tight that clusters can be used as perfect tracers of the large-scale matter distribution and thus for cosmological tests. The correlation of the X-ray traced cluster mass and the optical luminosity of the galaxy content of clusters shows that the dark matter and galaxy distribution are tightly connected, but we also observe a scatter which is so far not well understood. We further explore the correlation of the galaxy population mix with the geometry of the large-scale structure features. On larger scales we also find correlations of the properties of galaxy clusters with the density of their large-scale structure environment.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Magnetic fields are crucial to the generation of turbulence and the dynamics of accretion and energy dissipation in accretion disks. Nevertheless, until now, there has been no self-consistent analytic formalism that puts the evolution of turbulent magnetic fields on the same footing as other dynamical processes such as mass flow and energy generation. We have developed a self-consistent framework for turbulent, magnetized accretion disks with the aim of studying the processes that power hot coronae. Utilizing this framework we have identified the possible magnetic sources of power for the coronae of black hole accretion disks. The most promising is the Poynting flux associated with the azimuthal-vertical magnetic stress. We also determine how the emission from the disk is modified by the processes that power the corona and related winds.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We characterize the stellar population of a complete sample of the closest southern radio-galaxies – 12 Fanaroff-Riley I (FR I), 8 FR II and 4 with undefined FRx type – and a comparison sample of 18 non-active elliptical and SO galaxies. We measured equivalent widths and continuum colours and their radial variations, and performed spectral synthesis as a function of distance from the nucleus. Only 4 of the radio-galaxies have more than 10% of the total flux at 4020Å contributed from 100 Myr old or younger stellar population components – including a featureless continuum due to an AGN. All 4 are FRII or FRx. The main difference between the stellar population of the radio-galaxies and that of the non-active ones is that the former have a larger contribution of the intermediate age component, suggesting a relation between the present radio activity and a past episode of star formation which occurred about 1 Gyr ago.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html