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

We present the initial results of our analysis of line emission produced in gas disks found at the centers of a sample of nearby radio galaxies with radio jets. We obtained data using STIS (The Space Telescope Imaging Spectrograph) at three parallel slit positions on the nucleus of each galaxy. This allows us to map the Hα + [NII] flux, the gas radial velocity and the velocity dispersion. We found that we cannot rule out a rotating disk model for the gas in any case. We found that for 62% of the galaxies the fit is improved in the nucleus by the inclusion of an additional broad component. By comparing the observed central kinematics to model gas disks we were able to estimate the masses of nuclear black holes in 12 of the sample galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We here present our result of deep and wide-field narrow-band imaging of the region of the ‘proto-cluster’ at $z=3.1$ around the SSA22 field. We detected 283 highly confident Ly$\alpha$ emitter candidates (LAEs) and discovered that the belt-like high surface density region of these LAEs extends over $\approx 60$ Mpc in comoving scale, which is much larger than it was known previously. We then successfully detected the 35 extended Ly$\alpha$ blobs (LABs) which are larger than 16 arcsec$^2$ in isophotal area and brighter than $0.7 \times 10^{-16}$ ergs s$^{-1}$ cm$^{-2}$. The distributions of average surface brightness and morphology are widespread from relatively compact high surface brightness objects to very diffuse low surface brightness ones. For one third of these 35 LABs, simple photo-ionization by massive stars is not sufficient to explain the Ly$\alpha$ luminosities, and other mechanisms, such as gravitational heating or superwind must be considered. From their large size and strong spatial clustering, we consider that these LABs are objects closely related to the massive galaxies in their forming phase in the environment of the proto-cluster or large-scale structure.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present multi-object spectroscopic observations from FORS1 mounted at the VLT for 5 clusters detected in the ESO Imaging Survey. Together with the results for three other clusters presented previously, we confirm a total of 6 out of 8 clusters with estimated redshift $z_{MF}\geq0.6$. The spectroscopic redshifts are in good agreement with the estimated ones.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The role of stars and starbursts in AGN has been a recurring issue for nearly as long as AGN have been recognized as hosts of interesting phenomena. The heated “starburst versus monster” controversy of the 80's and 90's was gradually replaced by “starburst plus monster” studies, as observational work in the past decade has firmly established that accretion onto a super-massive black-hole and star-formation coexist in many galactic nuclei. Whereas the physical link between starbursts and AGN remains unclear, there remains no doubt that starbursts affect a number of properties traditionally associated to the AGN alone, such as the so called “featureless continuum”, emission line ratios and luminosities. This contribution glosses over some of the techniques used to diagnose stellar populations in AGN, focusing on recent results and how this type of work can lead us well beyond what became known as the starburst-AGN connection.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Past X-ray observations by ASCA suggest that warm absorbers (O VII and O VIII edges) are apparently rare in high luminosity AGNs (quasars) while they are more common in low luminosity AGNs (Seyferts). However, this could be a selection effect if high luminosity AGNs have mostly narrow absorption lines (with no strong bound free edges), which escaped detection by the low resolution of ASCA. To check this hypothesis we are studying the high-resolution X-ray spectra of quasars from grating spectrometers on board Chandra and XMM-Newton in search for absorption lines. In this contribution we present spectra of three quasars. The spectra show narrow (several hundred km s−1) absorption and emission X-ray lines from H-like and He-like ions of O, Ne, Mg, and other abundant elements. We also detect absorption from iron L-shell lines and iron M-shell unresolved transition array. We present the analysis of MR2251-178 where we find that at least two, and probably three, distinct warm absorbers are needed to explain the high resolution spectrum of this object. We re-analyze the high-resolution X-ray spectrum of PG 1211+143 and suggest that an outflow velocity of ∼3000 km s−1 provides an adequate explanation to these data. We also present preliminary results form the Chandra/HETGS observation of the quasar 4C74.26.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We study the NLR emission line spectrum of 12 NLS1s to constrain the EUV – soft X-ray continuum SED using accurate photoionization modeling. We find that the NLR emission line ratios, which we measure for several NLS1 galaxies, can be reproduced within ±15% without a strong BBB component in the framework of a two-component model.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The cross-correlating cosmic microwave background (CMB) fluctuations caused by the Sunyaev-Zel'dovich effect from observed clusters of galaxies with their redshifts can be used to measure the mean squared cluster peculiar velocity with an error $\sigma_{C_S^2}\simeq (300{\rm km/s})^2$. This can be done around $z\gt0.3$ with clusters of flux above 200 mJy which will be detected by PLANCK, coupled with high resolution microwave images to eliminate the cosmological part of the CMB fluctuations. The latter can be achieved with observations by the planned ALMA array or the NSF South Pole telescope and other surveys. By measuring the rms peculiar velocity of clusters and their bulk flow in, e.g., 4 spheres of $\sim 100h^{-1}$ Mpc at $z=0.3$, we could have a direct measurement of the matter density $0.21\lt\Omega_m\lt0.47$ at 95% confidence level.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Measuring stellar velocity dispersion (σ) in Narrow-Line Seyfert 1 (NLS1) with optical spectra, can be very difficult because of the large and bright Fe II multiplets, which completely suppress the typically used stellar absorption lines. Indeed, σ values are to date available only for 2 NLS1s. Here we present new σ measurements of three NLS1s observed in the spectral range centered around the Ca II triplet (λ∼8600Å). Moreover, we compare σ with the gaseous velocity dispersion finding that the σ = FWHM([O III]5007Å)/2.35 relation (Nelson & Whittle 1995) is not satisfied by our galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present Very Large Array observations at 1.4 and 5 GHz of a sample of 16 quasi-stellar objects (QSOs) at z = 1.78 to 2.71. These sources were chosen to have similar optical properties (MB, spectra) as samples of (z ≥ 3.7 QSOs) for which we have comparable (sub)millimeter (250 GHz or 350 GHz) and centimeter observations. Half of the chosen quasars are bright at 250 or 350 GHz while the other half have not been detected at (sub)mm wavelengths. All eight submm-loud sources in our study were detected at 1.4 GHz, the majority of these at high significance (≥0.2±0.02 mJy). Only three of the submm-quiet QSO's were detected at radio frequencies, and these at lower significance (≤0.17 mJy). These results argue for a real physical difference between the submm-luminous and submm-quiet sources, and against a continuum of submm luminosities. Four of these sources have radio spectral indices and radio-to-FIR ratios consistent with star forming galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

J and K-band imaging with Gemini N has resolved the host galaxies of QSOs of redshifts 4.7 to 5.2. We also discuss I and Z band imaging of two QSOs of redshift above 6.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We explore possible correlations between the light profile shapes of early-type galaxies, as parameterized by the Sérsic index $n$, and relevant stellar population parameters, which were obtained from spectra of extremely high signal–to–noise and stellar population models that provide an age indicator that is virtually free of the effects of metallicity. We do not find any robust correlation between $n$ and mean age or metallicity. However, we find evidence for a strong positive correlation between $n$ and [Mg/Fe] abundance ratio. We speculate that early-type galaxies settle up their structure on short time-scales in agreement with those imposed by their [Mg/Fe] ratios, suggesting that the global structure was already at place at high $z$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

LLAGN that include low-ionization nuclear emission-line regions (LINERs), and transition-type objects (TOs) represent the most common type of nuclear activity. Here, a study of the central stellar population of LLAGN is presented. Our goal is to search for spectroscopic signatures of young and intermediate age stars, and to investigate their relationship with the ionization mechanism in LLAGN. The method used is based on the stellar population synthesis of the UV-optical continuum of the innermost (20-100 pc) regions in these galaxies. Half of the LINERs and TOs of the Palomar catalogue are analysed. It is found that weak-[OI] ([OI]/Hα≤0.25) LLAGN have an intermediate age stellar population that dominates the optical light. But young stellar clusters dominate the UV continuum in these objects. These clusters can co-exist with a black-hole in spatial scales of a few pc. Most of the strong-[OI] LLAGN have a predominantly old stellar population. These results suggest that young and intermediate age stars do not play a significant role in the ionization of LLAGN with strong [OI].To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report the discovery of a probable large-scale structure composed of many galaxy clumps around the known twin clusters at $z=1.26$ and $z=1.27$ in the Lynx region. Our analysis is based on deep, panoramic, and multi-colour imaging with the Suprime-Cam on the 8.2 m Subaru telescope. We apply a photometric redshift technique to extract plausible cluster members at $z\sim1.27$ down to $\sim M^\ast+2.5$. From the 2-D distribution of these photometrically selected galaxies, we newly identify seven candidates of galaxy groups or clusters where the surface density of red galaxies is significantly high ($>$5$\sigma$), in addition to the two known clusters, comprising the largest most distant supercluster ever identified.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We study the formation and evolution of voids in the dark matter distribution using various simulations of the popular $\Lambda$ Cold Dark Matter Universe. We identify voids by requiring them to be spherical or elliptical regions of space with a mean overdensity of $-0.8$ or less. The distribution of void sizes in the different simulations shows good overlap. The size of a void is related to the depth of the smoothed density field at that position in the initial conditions. The rescaled mass profiles of voids in the different simulations agree remarkably well. We find a universal void mass profile of the form $\rho(\ltr)/\rho(r_{\rm eff}) \propto \exp[(r/r_{\rm eff})^\alpha]$ where $r_{\rm eff}$ is the effective void radius and $\alpha\sim 2$. The mass function of haloes in voids is steeper than that of haloes which populate denser regions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html