We study AGN jet formation by means of exact solutions of the relativistic magnetohydrodynamic equations. This is an original extension in Schwarzchild's metric of previous meridionally self-similar models. The outflow is mainly thermally driven to high asymptotic speeds from the central region where the escape speed is also high. The jet solutions are magnetically collimated on the sub-parsec scale.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present the preliminary result of our project, consisting in studying the properties of a large sample of galaxy clusters. The Münster Red Sky Survey, which is a large galaxy catalogue covering an area of about 5000 square degrees on the southern hemisphere, serves as our observational basis. It is complete up to $r_F=18^m.3$. Creation of a cluster catalogue is the first step of our investigation. We propose to use the 2D Voronoi tessellation technique for identifying galaxy clusters in this 2D catalogue. Points with high values of the inverse Voronoi tessel area will be regarded as galaxy cluster centroids. We show that this approach works correctly.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

VLT and NTT spectra are used to examine the nuclear and extended coronal line emission in a sample of well-known Seyfert 1 and 2 galaxies. The excellent spatial resolution obtained with VLT allowed us to map [Si VI] 1.963μm and [Si VII] 2.48μm on scales of up to 20 pc. Coronal line emission, extended to distances of ∼102 pc, is detected in some of the lines analyzed, particularly in [Fe X] 6374Å, [Fe XI] 7891Å, and [Si VII] 2.48μm. Most coronal lines are strongly asymmetric towards the blue and broader than low-ionization lines. This result is particularly important for Circinus, where previous observations have failed to detect larger widths for high-ionization lines. Photoionization models are used to investigate the physical conditions and continuum luminosities necessary to produced the observed coronal emission. We found that an ionization parameter U>0.10 is necessary to reproduce the observations, although the clouds should be located at a distance <30 pc from the central engine.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We provide the first direct lifting of the mass/anisotropy degeneracy for a cluster of galaxies, by jointly fitting the line of sight velocity dispersion and kurtosis profiles of the Coma cluster, assuming an NFW tracer density profile, a generalized-NFW dark matter profile and a constant anisotropy profile. We find that the orbits in Coma must be quasi-isotropic, and find a mass consistent with previous analyses, but a concentration parameter 50% higher than expected in cosmological $N$-body simulations. We then test the accuracy of our method on realistic non-spherical systems with substructure and streaming motions, by applying it to the ten most massive structures in a cosmological $N$-body simulation. We find that our method yields fairly accurate results on average (within 20%), although with a wide variation (factor 1.7 at 1$\sigma$) for the concentration parameter, with decreased accuracy and efficiency when the projected mean velocity is not constant with radius.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have studied how the active nucleus of the Seyfert 2 galaxy NGC 1068 influences the chemistry of its 200 pc circumnuclear disk of molecular gas (CND). Results from new observations made with the IRAM 30m telescope have served for deriving abundances of molecular species such as SiO, CN, HCO+, HOC+, H13CO+ and HCO. These estimates are complemented with a re-evaluation of abundances of HCN, CS and CO, based on previously published observations. We report on the first detection of significant SiO emission in the CND of NGC 1068. We also report on the first extragalactic detection of the reactive ion HOC+. Our conclusions favour an overall scenario where the CND of NGC 1068 has become a giant X-ray Dominated Region (XDR).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

This paper describes some useful results that can be obtained through long-term infrared photometric monitoring of Seyfert galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have embarked in an HST program to determine the masses of black holes in spiral galaxies directly by measuring the line emission arising from an extended accretion disk. For each of the galaxies in our sample we have measured the rotation curve and determined the mass distribution within the inner 5–50 pc. We have modeled the stellar mass component using the photometric data from existing HST images and using both data sets we have derived the masses of the black holes in each galaxy. These results will be very important in clarifying the role of the black hole in powering the AGN, will shed light into the effectiveness of the accretion mechanisms and finally will be important in addressing the fundamental issue of unification for Seyfert 1 and Seyfert 2 galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I will discuss a few select aspects of the most common and best understood galactic-scale outflow – starburst-driven superwinds, focusing on winds from nuclear starburst galaxies. I will show that modern observations, in particular in the soft and hard X-ray bands, complement and reinforce the existing paradigm of superwinds as flows collectively driven by multiple SNe. The properties of the diffuse X-ray emission from dwarf starburst galaxies, LBOL∼L[sstarf] starburst in spiral galaxies, and ULIRGS, are all consistent with superwind activity. Where appropriate, I contrast the physics of starburst-driven winds with poorly collimated winds from AGN, and discuss what we know of the role of LLAGN and Seyfert nuclei in starburst superwind galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I review recent results of cosmological hydrodynamic simulations for clusters of galaxies. Such simulations have developed into an increasingly powerful tool to make theoretical predictions for clusters, and to confront them with observations. I focus, in particular, on the continuing challenge to reproduce the observed cluster X-ray scaling relations in CDM simulations. Self-consistent simulations that include radiative cooling, star formation and supernova feedback generally overpredict the X-ray luminosity on group scales and exhibit overly strong cooling flows. Solving these problems may require the consideration of more physics in cluster simulations, for example thermal conduction or heating by a central AGN.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present a dynamical analysis of the central $\sim$ 1.3 square degrees of the galaxy cluster Abell 1367, based on 272 redshift (of which 118 are new measurements). From the analysis of the 146 confirmed cluster members Abell 1367 appears as a young cluster currently forming at the intersection of two filaments.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Brightness variations across the entire electromagnetic spectrum, occurring at several time scales, are known properties of blazars. The variability of the continuum emission may be related to the formation and propagation of shock waves in the relativistic jet. In this case we may expect variations also in the degree of polarization and its position angle. In order to effectively constrain such models, we begun in 2003 a program to monitor the optical polarimetry of a sample of blazars, of which we present here the first results.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The interplay between stellar populations and gas in local starburst galaxies is analyzed using images from the Hubble Space Telescope to map the ages of the young stellar components and to isolate the contribution of shocks on spatial scales ranging from a few tens of pc to ∼1 kpc. The shocked gas represents a small fraction of the total ionized gas in these objects, yet it can have profound effects on the long–term evolution of the starburst, which may include the triggering of new star formation.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We used the near-infrared [Fe II] emission line signature of shock-heating to detect supernova remnants (SNRs) in nearby starburst galaxies. The near-IR narrow-band imaging program has led to the detection of SNR candidates in NGC 1569 and NGC 5253, both host to super-star clusters. A spatially extended component to the [Fe II] line emission dominates the integrated [Fe II] luminosity in the two galaxies. Despite the starburst environment, the [Fe II] luminosity of the individual SNRs is two orders of magnitude lower than the luminosities observed for SNRs in M82. We find that the density and the structure of the interstellar medium is a more important factor than the starburst nature of a galaxy in determining the average [Fe II] luminosity of a SNR. The observations suggest that a significant fraction of the ISM in NGC 1569 and NGC 5253 is under the influence of SNRs. This does not appear to be the case in M82 where the impact of the SNRs is limited to high density knots.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Ellipticals in very low density environments are extremely rare but hold important clues about galaxy formation and evolution. We present results of an investigation of their internal dynamics. We observe a dichotomy in kinematic properties similar to that in normal ellipticals. We compare the positions of isolated ellipticals with respect to the Fundamental Plane of normal ellipticals and find that they fall onto it, with the exception of NGC 2865. This shows that isolated ellipticals are structurally similar to normal ellipticals, and do not have very young ages, although some have signs of past mergers or interactions.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Photometric properties (effective surface brightness, effective radius, radial profile index, axis ratio, color, color gradient) of 328 galaxies in the Coma cluster fainter than $R=15$ mag are examined as a function of the distance from the cluster center. No significant gradient is found for the effective surface brightness, effective radius and radial profile index. The distribution of axis ratios shows a concentration of round galaxies at the cluster center in the magnitude range $16.5 \lt R \lt 18$; most of these are found to be old and to have intermediate metal abundance, suggesting that they are nucleated dwarf ellipticals. On the other hand, we find a significant gradient in color, in the sense that galaxy colours become bluer with increasing distance from the cluster center. We conclude that this color gradient represents a metallicity gradient.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The H I deficiency pattern of the spiral population in the Virgo cluster region reveals a significant number of galaxies at very large clustercentric distances with gaseous deficiencies comparable to those measured in the cluster centers. We have used the output of cosmological $N$-body simulations to investigate whether the gas-deficient galaxies on the outskirts of the Virgo cluster may have previously passed through its core. We find that the maximum radius reached by infalling galaxies as they bounce out of a Virgo-like cluster must be less than 2.5 virial radii, which results in a predicted velocity-distance diagram noticeably different from the one drawn by the data. The latter is fairly well reproduced, however, after including in the simulations distance errors at the 20% relative rms level. Yet, for several objects apparently over 5 Mpc in front or behind the Virgo center the assumption that they are instead close enough to the cluster to have passed already through its core strains the bounds of plausibility. Hence, unless these outlying H I-deficient Virgo's spirals have grossly incorrect distances, they cannot have lost their gas by interactions with the intracluster medium. This suggests that the evolution of spirals might begin already on the suburbs of clusters.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The warm-hot intergalactic medium contains a major part of all baryons in the universe. Despite this, it is very hard to observe in X-rays due to its relatively low temperature and the poor spectral resolution of most instruments. The high sensitivity and good spectral resolution of XMM-Newton allowed for the first time to show the presence of the warm-hot intergalactic medium in the outskirts of several nearby clusters of galaxies. In this contribution these results are presented. The physical state of the gas such as temperature, density, mass and chemical composition are discussed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The cluster soft excess emission indicates the presence of large amounts of warm gas ($T\sim10^6$ K) in the neighborhood of galaxy clusters. Among the clusters that display this phenomenon is the Coma cluster, the nearest rich galaxy cluster. The excess emission is more prominent at the cluster's outskirts than at its center. Detailed studies of its large-scale emission–up to $\sim 2.6$ Mpc from the cluster's center–reveal that these warm baryons are as massive as, or possibly more massive than, the well-known hot intra-cluster medium ($T\sim10^8$ K). A possible interpretation of the excess emission from the Coma cluster is radiation from low-density filaments located in the neighborhood of the cluster. In this case, the filaments would extend for much larger distances, or feature higher density, than predicted by current cosmological simulations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present near-infrared imaging of the host galaxies of 17 quasars at 1 < z < 2, obtained with ISAAC at the ESO VLT UT1 under excellent seeing (∼0.4 arcsec). The radio-loud (RLQ) and radio-quiet (RQQ) quasars in the sample have similar distribution of redshift and optical luminosity. Both RLQ and RQQ hosts follow the cosmic evolution of massive inactive ellipticals undergoing passive evolution. This indicates that nuclear activity can occur in all luminous ellipticals without producing a significant change in their global properties and evolution. However, there is a systematic difference by a factor ∼2 in the host luminosity between RLQs and RQQs, which remains the same from z = 2 to z = 0. Quasar hosts are already well formed at z ∼2, in disagreement with hierarchical models of AGN and galaxy formation and evolution models. No correlation is found between the nuclear and the host luminosities. If the host luminosity is proportional to the black hole mass, as in nearby massive spheroids, both types of quasars emit at very different levels with respect to their Eddington luminosity.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have analyzed the frequency and properties of the nuclear activity in two samples of galaxies, with and without circumnuclear rings and spirals (CNRs). We discuss the relevance of the results in the framework of the AGN feeding processes and some results are: (i) bright companion galaxies seem not to be important for the appearance of CNRs, therefore these would be more related to intrinsic properties of the host galaxies or to minor merger processes; (ii) the proportion of strong bars in AGN galaxies with a CNR is higher than the expected rate of strongly barred AGN galaxies from the sample of Ho and co-workers; (iii) the incidence of Seyfert activity coeval with CNRs is clearly larger than the expected rate from the morphological distribution of the host galaxies; (iv) the rate of Sy 2 to Sy 1 in galaxies with CNRs is larger than the expected proportion for galaxies without CNRs; this proportion would be in the opposite sense as expected from the geometric paradigm of the classical unified model for AGNs, but supports a scenario where Sy 2 activity is linked to circumnuclear star formation.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html