Atomic gas in the central kiloparsec of young radio galaxies is quite prevalent, as revealed by 21cm H I absorption line observations using the WSRT. The column depths are anti-correlated with the linear sizes of the radio sources, but VLBI reveals that sometimes the neutral hydrogen is situated in a disk or torus on parsec or sub-kiloparsec scales around the central engine, while in other cases the H I is probably associated with star-forming regions along the jets. NGC 1052 is a nearby example, in which, next to some isolated clouds along the jets, there appears to be an atomic and molecular torus with a radius of a few parsecs, but with a central hole of about 0.5 pc, in which the gas is mostly ionised.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

First results from the AGN-Heidelberg program aimed at spatially resolving the central pc region of the closest Active Galactic Nuclei are presented. The core region of prototype active nuclei are clearly unveiled at IR waves and at distances from the nucleus – few pc- where circumnuclear starforming regions appear not to be present. Within that perspective, classical active nuclei as Circinus and NGC 1097, reveal with unprecedented detail clear channels of material being driven to the core whereas others as Centaurus A and NGC 5506, show a “clean” core environment. At the very center, a central compact region of ∼2 pc scale is resolved in Circinus but not in the other cases challenging thus the universal presence of the putative obscuring torus.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Analysing mid–infrared ISOCAM images of the cluster of galaxies J1888.16CL, we identified among its members several particularly active galaxies with total infrared luminosities well above $10^{11}~\Lo$. If powered by dust enshrouded starbursts, as suggested by their optical spectra, these Luminous Infrared Galaxies would exhibit star formation rates surprisingly high in the cluster environment. The triggering mechanism is unclear but could be tidal collisions within sub-structures or infalling groups.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In this paper we report on our recent results connected with the direct environment of the super massive black hole of the Milky Way. The data are obtained using the VLT facilities (ISAAC and NAOS/CONICA instruments) in the near- and mid-infrared wavelength ranges. We provide a calibration of the foreground and local differential (in wavelength and spatially) extinction of the Galactic Center and report on the discovery of a new complex of infrared excess sources (possibly young stars) located at the northern part of the IRS 13 cluster. Finally, we discuss the origin of filamentary structures observed in the L-band images.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I describe very briefly the new libraries of empirical spectra of stars covering wide ranges of values of the atmospheric parameters Teff, log g, [Fe/H], as well as spectral type, that have become available in the recent past, among them the HNGSL, MILES, UVES-POP, and Indo-US libraries. I show the results of using the HNGSL to build population synthesis models. These libraries are complementary in spectral resolution and wavelength coverage, and will prove extremely useful to describe spectral features expected in galaxy spectra from the NUV to the NIR.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Popular internal shock models, developed to explain the production of high energy flares in blazar jets, involve collisions between local overdensities of matter being ejected by a central engine and moving along the jet with different velocities. Prior to such collisions, the matter is relatively cold and therefore does not produce intrinsic non-thermal radiation. However, due to Comptonization of external radiation by cold electrons, the presence of such matter should be apparent by prominent precursor soft X-ray flares. We discuss the predicted properties of such precursors.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the analysis and results of a new spectroscopic and photometric survey of the central 1.5 ${\rm Mpc}^2$ region of the galaxy cluster A3921 (z=0.094). We detect the presence of two dominant clumps of galaxies with a mass ratio of $\sim$4-5: a main cluster centered on the BCG (A3921-A), and a NW sub-cluster (A3921-B) hosting the second brightest cluster object. By comparing optical results to the X-ray analysis of XMM observations (Belsole et al. 2004), we find that A3921-B is tangentially traversing the main cluster along a SW/NE direction. The analysis of stellar populations of more than one hundred cluster members reveals that the merger event has probably affected the kinematics and spectral properties of the active galaxies in A3921.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We use preliminary results of WINGS survey (Fasano et al.) to obtain determinations of optical scaling relations for galaxy clusters. Passing from one- to two- parameter scaling relations we pay particular attention to the Kormendy relation (KR) and to the Fundamental Plane (FP) of galaxy clusters, comparing them with scaling relations of elliptical galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A detailed analysis of the spectrum of I Zw 1 shows that the Narrow Line Region, unlike that of most Seyfert 1 galaxies, is a very low excitation region dominated by both permitted and forbidden Fe II lines. The physical conditions in this region are discussed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

From a long-term study of IR mergers/QSOs (at low redshift), we report detailed spectroscopic evidences for outflow (OF)and starburst features. We found extreme velocity OF (EVOF) in IRAS 01003-2238, 11119+3257, 13218+0552, 14394+5332, 15130-1958 and 15462-0450. The EVOF were detected mainly in objects with strong starburst plus obscured IR QSOs. Meanwhile, the low velocity OF components were detected in objects with starburst and LINER processes. HST images of IR+BAL+Fe II QSOs show in practically all of these objects “arc or shell” features probably associated to galactic-winds. In addition, results from a study of two-dimensional (2D) fibre spectroscopy of IR mergers/QSOs with galactic winds are presented. Comparing our data base for IR mergers/QSOs with two sample of nearby mergers we found in both samples a high proportion (75 per cent) of IR mergers with galactic winds.

From a very deep imaging and spectroscopic survey of Lyα emitters (LAEs) at z=5.7 we present the results of a study of sample of 20 LAEs candidates. Two of these objects have been already confirmed as LAE at z = 5.7. We detected in one of these LAE (at z=5.687), spectral features probably associated with the more distant galactic wind observed to date.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The abundance of α-process elements such as magnesium and carbon relative to iron, measured from the broad emission lines of QSOs, can serve as a diagnostic of the star formation and chemical enrichment histories of their host galaxies. We investigate the relationship between Fe/Mg and Fe/C abundance ratios and the resulting Fe II / Mg II λ2800 and Fe II / 1900Å-blend flux ratios, both of which have been measured in QSOs out to z≈6. Using a galactic chemical evolution model based on a starburst in a giant elliptical galaxy, we find that these flux ratios are good tracers of the chemical enrichment of the nuclei. However, the values of these ratios measured in objects at z≈6 suggest that iron enrichment has occurred more rapidly in these objects than predicted by the assumed elliptical starburst model, assuming currently favored cosmologies. This in turn suggests that refinements to the galactic chemical evolution models are needed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The outskirts of clusters are dynamically complex regions populated by galaxies falling into the cluster potential for the first time as well as some which have already visited the cluster core. Addressing the properties of galaxies in these transition regions requires the integration of cluster dynamics, an understanding of environmental influences on galaxies at both high and low densities and hierarchical scenarios of cluster formation and growth. In this review I describe some recent observational results on galaxies in the outskirts of clusters, and the evolution of galaxies in clusters as a function of local density and radius.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Standard models of galaxy formation make specific predictions for how galaxy properties depend on environment. These predictions follow from the assumption that galaxy properties are entirely determined by the formation histories of the halos which host them, and that the distribution of dark halo masses is skewed towards large masses in dense regions. We describe two tests of this assumption which can be made with currently available data.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Cluster mergings are expected to have an influence on the radio emission of the galaxy population. We present the results of a deep radio survey in the A3558 complex in the central region of the Shapley Concentration, in order to further explore our hypothesis of a dependence of the radio luminosity function on the age of the merging.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Observing the neutral hydrogen in galaxy clusters provides crucial insights in the physical processes that influence the evolution of gas-rich galaxies as they migrate from the lower-density filaments through the cluster outskirts into to the higher-density central regions. The morphology-density relation, the Butcher-Oemler effect, and the observed HI deficiencies in the central regions of galaxy clusters suggest that infalling galaxies experience a strong transformation of their morphologies, star formation rates, and gas content. The physical mechanisms that trigger and govern these transformations may depend strongly on environment. This contribution aims to illustrate that the morphological and kinematic characteristics of the cold gas provide a sensitive tool to determine which mechanisms dominate in which environments.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

It was suggested by Terlevich & Melnick (1985) that many nuclei classified as Seyfert 2s could be associated with WR stars recently formed in a powerful starburst. Since then, the signature of WR stars has been claimed to be observed in several Seyfert 2s and LINERs. Gonçalves et al. (1999) have shown that a small number of Seyfert 2s have very weak [N II] 6548,6584 lines, suggesting that these objects could be partly ionized by WR stars. We have obtained high S/N spectra of such “Weak-[N II] Seyferts” to investigate if WR stars can be observed in galaxies without any other evidence for a starburst nebulosity. Amongst other findings, we have detected the presence of emission features such as Si II 5056,6347 and Ni II 7380. Other lines, such as [Ar VI] 4711,4740 and [Fe III]4658 are possibly present, mimicking the Bowen blend.

The detection of WR stars in AGN poses interesting questions concerning the link between nuclear activity and star formation, providing another angle to the study of the Starburst–AGN connection. However, one must be very careful in interpreting the available data; for the time being, the role played by WR stars in these AGN remains an open debate.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

It is possible that narrow-line Seyfert 1 galaxies (NLS1s) are in the early stage of active galactic nuclei (AGNs) evolution. It is important to estimate the mass of supermassive black hole (SBH) in NLS1s. Here we considered the different kinds of methods to estimate the SBH masses in NLS1s. The virial mass from the Hβ linewidth assuming random orbits of broad line regions (BLRs) is consistent with that from the statured soft X-ray luminosity, which showed that most of NLS1s are in the super-Eddington accretion state. The mass from the [O III] linewidth is systematically larger than that from above two methods. It is necessary to measure he bulge stellar dispersion and/or bulge luminosity in NLS1s.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the analysis of intrinsic UV absorption in the Seyfert 1 galaxy Mrk 279, observed simultaneously with HST/STIS (40 ks) and FUSE (92 ks). To derive the absorption covering factors and ionic column densities, we employ an algorithm based on minimizing errors in simultaneous fits to multiple lines. This technique allows for the treatment of more complex (and physically realistic) scenarios of the absorption-emission geometry, giving more accurate measurements and unique geometrical constraints on the mass outflow.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present here the self-similar collapse of a relativistic singular isothermal sphere (SIS) that leads to monolithic black hole formation. The dynamic evolution is triggered by the central portion of the SIS collapsing to for an infinitesimal black hole. This perturbation removes the pressure support for the layer immediately above, which causes it to collapse, and so on. The influence of gravitational collapse propagates out as an expansion wave moving at the speed of sound. Outside of the expansion wave, matter remains in local equilibrium.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A main topic at this meeting is how galaxies are affected when they enter for the first time the cluster environment from the outskirts. Most of the times we are forced to infer the environmental effects indirectly, relying on systematic variations of galaxy properties with environment, but there aren't many examples of direct observations able to unveil ongoing transformations, and the corresponding mechanism producing it. We present a case in which it is possible to identify the cluster environment, and in particular the intracluster medium and the recent infall history of galaxies onto the cluster, as the cause for a recent, abrupt change in the evolutionary history of galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html