We present a semi-analytic model able to trace the thermalisation history of the ISM in a Starburst region and determine the SN heating efficiency evolution.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have analyzed the position angle (PA) differences between radio jets and dust distributions in the centers of Fanaroff & Riley Type 1 (FRI) radio galaxies. We model the observed PA differences to infer the three-dimensional relative orientation of jet and dust. Our main conclusion is that there is a dichotomy in dust-jet-galaxy orientation both in projection and in three-dimensional space. The orientation dichotomy can explain the contradictory results obtained in previous studies. We briefly mention scenarios that might explain the dichotomy.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Near-infrared and optical imaging of BL Lac host galaxies is used to investigate their colour properties. We find that the R–H colour and colour gradient distributions of the BL Lac hosts are much wider than those for normal ellipticals, and many objects have very blue hosts and/or steep colour gradients. The blue colours are most likely caused by recent star formation. The lack of obvious signs of interaction may, however, require a significant time delay between the interaction event with associated star formation episodes and the onset of the nuclear activity.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In this paper I address three topics. The first regards the use of composite spectra as a tool to study the spectral evolution of galaxies in intermediate-redshift clusters. This technique is used to demonstrate the robustness of measurements of strong H$\delta$ absorption, indicative of mild-to-moderate starbursts, in a significant fraction of galaxies in these clusters. Second, I present some spectroscopic data on Abell 851 ($z=0.41$) that suggests that the starbursts in this cluster have been triggered by tidal encounters in infalling groups in the cluster. Third, I briefly describe the IMACS imaging-spectrograph, which has been built for the Magellan-Baade telescope, and, following the idea that the outskirts of clusters are “where the action is,” describe a large spectroscopic program to study “cluster building” using IMACS.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We estimate the gas mass fractions for a sample of 39 high-$z$ galaxy clusters using a combination of three different data sets: Chandra X-ray data, OVRO/BIMA centimeter-wave Sunyaev-Zel'dovich Effect (SZE) data, and published weak gravitational lensing data. The gas mass fraction $f_g$ is calculated in three different ways. The X-ray surface brightness and SZE decrement are used independently to determine the number of baryons in the intracluster gas and subsequently the gas mass; the total mass follows assuming spherical symmetry and hydrostatic equilibrium (HSE). The third, less model-dependent approach is to calculate the projected SZE gas mass along a cylinder and divide by the total mass derived from the lensing data. The goal of this study is to compare the $f_g$ results from the three different methods to investigate systematic uncertainties associated with clumping of the intracluster medium, cluster elongation, and the HSE assumption.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A solid observational characterization of cluster regions around the virial radius would allow us to improve considerably our understanding of the physics of galaxy clusters as a whole: sadly current and planned experiments will not allow us to study these regions. Unbeknownst to most but not all, the development of an experiment sensitive to cluster outer regions could be achieved with currently available technology, with no need for breakthroughs. Amongst the major factors that will decide whether and when such an experiment will be flown are the awareness of the cluster community of the importance of such a mission and its determination at supporting it.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We show that Massive Black Holes of AGNs follow the same approximately linear relation with the luminosity of the host spheroid (bulge) found in normal (quiescent) galaxies, with the black hole mass being 0.002 that of the bulge. We also demonstrate that Narrow line AGNs seem to have a significantly lower Mbh/Lbulge ratio, which implies a new strong correlation between Mbh/Lbulge and the width of the broad emission lines of AGNs (Wandel 2002). Combining existing data, new observations and extrapolation schemes based on the Faber-Jackson relation, the relation between the BH mass and the stellar velocity dispersion in the host bulge of AGNs is constructed. It too agrees with the relation found in quiescent galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

By means of 2D spectroscopy we have found a lot of compact inner stellar and gaseous disks in morphologically normal galaxies. The evolution and spatial orientation of these inner structures are often decoupled from the evolution and spatial orientation of the large-scale galactic disks and bulges. We argue that this finding requires substantial change of common approaches to investigations of the central parts of galaxies, including central black hole studies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report the results of combined Chandra, HST/STIS, and FUSE observations of the intrinsic absorption in the Seyfert 1 galaxy NGC 4151. Our previous studies revealed an unusually large column of outflowing gas, very close to the nucleus, which responds rapidly to changes in the ionizing continuum due to its high density. With the latest observations, we have discovered evidence that the large absorbing column consists of individual high and low ionization components, and that the column density of the latter has decreased due to bulk motion across our line-of-sight. The Chandra spectra have revealed the signature of both very high ionization lines such as H-like and He-like Si, and inner-shell lines from low ionization species which may be associated with the UV absorbers. With the FUSE observations, we have detected lines from less abundant elements, which have permitted us to constrain the physical conditions and covering factors of the UV absorbers. These results indicate a complex and heterogeneous absorbing system, the extreme properties of which are likely the result of a relatively large viewing angle with respect to the accretion-disk axis.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using N-body numerical simulations, we investigate the stability of a nuclear disk of a few pc characteristic radius, around a supermassive black hole (SBH), and embedded in a galactic bulge. We find that with an SBH of a suitable range of mass, placed at its center, the nuclear disk is subject to one-armed (m=1) natural instabilities. We propose a feedback cycle for this mode, based on waves between corotation and OLR, and where the “indirect term”, and the massive bulge play a fundamental role. Nuclear disks formed from accreted gas could be the precursors of this type of structure and may be common in central regions of galaxies. Density waves could be an efficient mechanism of fueling the gas in the central few tens of parsecs in galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present results from a weak lensing survey of a sample of 53 clusters of galaxies at $0.15 < z < 0.4$, selected based on their high X-ray luminosities. For each cluster, we measure the mass-to-light ratio out to a radius $R \sim (0.5-1.5) h^{-1}$ Mpc. By measuring the lensing masses of a large sample of clusters in a consistent way, we quantify the intrinsic scatter in $M/L$ and determine its average value for massive clusters. In the near future, an ongoing spectro-photometric and weak lensing survey of a supercluster region in Aquarius will extend $M/L$ measurements to much larger radii and explore its dependence on scale and environment.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have reanalyzed in a consistent way existing reverberation data for 35 AGNs for the purpose of refining the black hole masses derived from these data. We find that the precision (or random component of the error) of reverberation-based black hole mass measurements is typically around 30%, comparable to the precision attained in measurement of black hole masses in quiescent galaxies by gas or stellar dynamical methods. As discussed in this volume by Onken et al., we have established an absolute calibration for AGN reverberation-based masses by assuming that AGNs and quiescent galaxies follow an identical relationship between black hole mass and host-galaxy bulge velocity dispersion. The scatter around this relationship implies that the typical systematic uncertainties in reverberation-based black hole masses are smaller than a factor of three. We present a preliminary version of a mass–luminosity relationship that is much better defined than any previous attempt. Scatter about the mass–luminosity relationship for these AGNs appears to be real and could be correlated with either Eddington ratio or source inclination.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present simulation results about the interplay between super star clusters (SSCs) and the host dark-matter (DM) halo, with emphasis on the formation of bulges in very late-type galaxies. Simulations show that the NFW halo close to a stable state has no significant response to sinking of circumnuclear SSCs. Generally speaking, while the halo becomes hotter, its central cusp survives. The structures of the formed bulges are similar to what we obtained with fixed NFW halos, but the bulge formation fraction at various stages are smaller.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

There is a tight M−σ relation in nearby inactive galaxies. Nearby radio-quiet AGNs also followed this relation. In order to investigate whether radio-loud AGNs and NLS1s follow this relation or not, we estimated their central black hole masses from Hβ and the bulge velocity dispersions from [O III] linewidth. We found that radio-loud AGNs and NLS1s seemed to deviate from this relation.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using high-resolution non radiative SPH simulations we study the scaling laws of galaxy clusters. In particular, we analyze the relations existing between total mass, gas temperature, X-ray luminosity and dark matter velocity dispersion. Our aim is to understand how these scaling laws depend on numerical, statistical and physical parameters, in order to model and thus reduce potential systematical uncertainties. The simulations were performed by the GADGET code in a $\Lambda CDM$ cosmology, applying resimulation techniques; their mass resolution ranges between $2 \times 10^9$ and $6.8 \times 10^9 h^{-1}M_{\odot}$ for dark matter particles and between $3 \times 10^8$ and $7 \times 10^8 h^{-1}M_{\odot}$ for gas particles.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We are using VIMOS to conduct a wide-field spectroscopic survey covering fields of $0.5 \times 0.5\,\mathrm{deg^2}$ around the X-ray luminous clusters of galaxies Abell 1689 ($z=0.185$) and Abell 1835 ($z=0.25$). Here we describe the observations and first results on the redshift distribution of subsamples of cluster galaxies to $R\simeq22$ for which we at present have obtained secure redshifts. These subsamples constitute $\sim 40\%$ of the total spectroscopic sample and contain 525 and 630 cluster members in Abell 1689 and Abell 1835, respectively, placing them amongst the largest redshift samples available for any cluster of galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Sensitive Infrared Spectral Energy Distributions (SEDs) drawn from the ISO data archive and supplemented with SCUBA and MAMBO observations, provide evidence for the geometric unification of powerful 3CR radio galaxies as “edge-on” quasars. Furthermore, detailed SEDs of 64 Palomar-Green quasars show a diversity of shapes, consistent with the physical evolution of the heating sources and the dust distribution around them.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Nuclear spirals can provide a wealth of information about the nuclear potential in disc galaxies. They form naturally as a gas response to non-axisymmetry in the gravitational potential, even if the degree of this asymmetry is very small. Linear wave theory well describes weak nuclear spirals, but stronger asymmetries in the potential induce waves beyond the linear regime, which appear as spiral shocks. If a central massive black hole (MBH) is present, spiral shocks can extend all the way to its immediate vicinity, and generate gas inflow up to 0.03 M$_{\odot}\,$ yr−1. This coincides with the accretion rates needed to power local Active Galactic Nuclei.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A multi-object spectroscopy follow-up survey of galaxy clusters selected from the Red-sequence Cluster Survey (RCS) is being completed. About forty clusters were chosen with redshifts from 0.15 to 0.6, and in a wide range of richnesses. One of the main science drivers of this survey is a study of internal dynamics of clusters. We present some preliminary results for a subset of the clusters, including the correlation of optical richness with mass, and the mass-to-light ratio as a function of cluster mass.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html