The youngest super star clusters (SSCs) in the Antennae Galaxies (NGC 4038/39) drive supersonic mass-loaded outflows. High-resolution Keck/NIRSPEC spectroscopy reveals broad, spatially extended Brγ emission lines that are well-fit by simple wind models. Cluster mass-loss rates are up to 1.5 M⊙ yr−1 and terminal velocities are up to 205 km s−1. These emission-line clusters (ELCs) constitute at least 15% of the star formation rate in the Antennae, and their high star formation efficiencies imply that they will probably evolve into bound SSCs. The youngest ELC outflows are driven primarily by stellar winds, and they efficiently entrain ambient matter. They transfer or dissipate most of their energy and momentum in a hot or cool medium that does not emit Brγ. ELCs are the individual engines that power galactic-scale superwinds, viewed in their earliest evolutionary stage.

The fragmentation of supershells and filaments driven by a superwind in a starburst region produces clumps with a mass spectrum approximated by a power law. Its spectral index is close to −2.3. We present results of computer simulations using the thin shell approximation, which are compared to 3D hydrodynamical simulations with self-gravity using the ZEUS computer code. In a low density medium the fragmentation time-scale is comparable to the collisional time-scale, and consequently collisions change the mass spectra of fragments to less steep values. In high density environments collisional time-scales are much longer and the mass spectrum results from gravitational fragmentation of expanding sheets and filaments.

The interstellar medium heated by supernova explosions (SN) may acquire an expansion velocity larger than the escape velocity and leave the galaxy through a supersonic wind. Galactic winds are effectively observed in many local starburst galaxies (Lehnert & Heckman 1996). The SN ejecta are transported out of the galaxies by such winds which must affect the chemical evolution of the galaxies. The effectiveness of the processes mentioned above depends on the heating efficiency (HE) of the SNs, i.e., the ratio between the kinetic plus internal energy density of the ambient gas and the SN energy density. In a starburst region, several SN explosions occur at a large rate inside a relatively small volume. If the successive generations of SN remnants (SNRs) interact with each other very fast, then a superbubble of high temperature and low density will rapidly develop, before a significant increase of the ambient gas density that could lead to substantial losses of energy by radiation. In this case, it is common to assume a value for HE of the order of unity, since most of the available energy of the SNs will be transferred to the ambient gas in the form of kinetic and internal energy, instead of being radiated away. However this assumption fails to reproduce both the chemical and dynamical characteristics of most starburst (SB) galaxies. In order to solve this paradigm, we have constructed a simple semi-analytical model, considering the essential ingredients of a SB environment, i.e., a three-phase medium composed by hot diffuse gas, SNRs and clouds, which is able to qualitatively trace the thermalisation history of the ISM in a SB region and determine the HE evolution (Melioli, de Gouveia Dal Pino, & D'Ercole, A&A, 2003, submitted). Our study has also been accompanied by fully 3-D radiative cooling, hydrodynamical simulations of SNR-SNR and SNR-clouds interactions (see Melioli, de Gouveia Dal Pino, & Raga 2003, in preparation).

The metal enrichment of the intra-cluster medium within a hierarchical structure formation scenario is investigated using a combination of N-body + Hydro simulations and semi-analytic models of galaxy formation. In our simulation, rates and sites of star formation are identified and gas particles in the environment of these ‘galaxies’ are then enriched with metals using various prescriptions. We investigate the paths of enriched particles, demonstrating how gas enriched at higher redshifts is distributed in a cluster after it has formed. We are then able to predict a number of observable quantities such as the radial profiles of metals from both SNII and SNIa and the evolution of metal content with redshift.

We present fully cosmological, hydrodynamical simulations of clusters of galaxies, including star formation, supernova feedback, chemical enrichment and metal-dependent cooling. We investigate the relation between feedback, metal enrichment of the intra-cluster medium (ICM) and the distribution of baryons in the various phases (cold gas+stars and hot ICM) at varying Initial Mass Function and wind efficiency.

We present a summary of our recent results on gas outflows in radio galaxies. Fast outflows (up to 2000 km s−1) have been detected both in ionized and neutral gas. The latter is particularly surprising as it shows that, despite the extremely energetic phenomena occurring near an AGN, some of the outflowing gas remains, or becomes again, neutral. These results are giving new and important insights on the physical conditions of the gaseous medium around an AGN.

Winds and outflows in starburst galaxies and AGN provide important information on the physics of the ‘central engine’, the presence and evolution of (nuclear) starbursts, and the metal enrichment of the nuclear environment and the intergalactic medium. Here, we concentrate on two examples, X-ray observations of the (U)LIRG NGC 6240 and the BAL quasar APM 08279+5255.

We present our new spatially-resolved, optical spectroscopy of the giant Lyα nebula around the powerful radio galaxy 1243+036 (=4C+03.24) at z = 3.57. The nebula is extended over ~ 30 kpc from the nucleus, and forms a pair of cones or elongated bubbles. The high-velocity (~ −1000 km s−1; blueshifted with respect to the systemic velocity) Lyα-emitting components are detected at both sides of the nucleus along its major axis. We discuss possible origin of the nebula; 1) the shock-heated expanding bubble or outflowing cone associated with the superwind activity of the host galaxy, 2) halo gas photoionized by the anisotropic radiation from the active galactic nuclei (AGN) and 3) the jet-induced star-formation or shock. The last possibility may not be likely because Lyα emission is distributed out of the narrow channel of the radio jet. We show that the superwind model is most plausible since it can explain both the characteristics of the morphology (size and shape) and the kinematical structures (velocity shift and line width) of the nebula although the photoionization by AGN may contribute to the excitation to some extent.

Winds from AGN and quasars will form large amounts of dust, as the cool gas in these winds passes through the (pressure, temperature) region where dust is formed in AGB stars. Conditions in the gas are benign to dust at these radii. As a result quasar winds may be a major source of dust at high redshifts, obviating a difficulty with current observations, and requiring far less dust to exist at early epochs.

We present the results of a recent long XMM-Newton and Chandra observation on the Seyfert 1 galaxy NGC 5548. This galaxy has a warm absorber with a wide range of ionization stages. The detection of O VI in both the UV and X-rays allows for a direct comparison of the measured column density in both wavelength bands. We also comment on the detection of O V, and its newly measured wavelength.

Observational data from the X-ray through the UV and optical of variations of the NGC 4151 nucleus were compiled. The characteristics of the variability related to the 1989-1996 cycle of activity show remarkable similarity to those of blazars and do not contradict the supposition that this cycle of activity was caused by a synchrotron jet (SJ). Some of the activity of previous cycles were interpreted in the framework of a SJ model and some of that of a disc instability model (DI). We ask the question if different cycles of activity can be of a different nature caused by a different accretion rate.

Data collected from the optical through infrared to the radio show that the Seyfert galaxies NGC 1275, NGC 3227, NGC 4151, NGC 5548 and NGC 7469 exhibit signs of flows or jets. The characteristics of night-to-night variations of Balmer line profiles and/or intranight continuum variations were obtained and investigated at the Crimean Astrophysical Observatory. They permit to suppose, that short term variability of the Balmer lines and intranight continuum variations can be produced in short lived shocks as a result of strong energy output in the form of gas flows or jets.

X-ray spectroscopy provides a wealth of information about the properties of the surrounding reprocessing material of AGN. We present results from a 96 ks exposure of NGC 3227, taken with the Low Energy Transmission Grating Spectrometer on board the Chandra X-ray Observatory. A partial covering model fits well the resulting X-ray spectrum. We investigate the dusty nuclear environment of this galaxy, and in particular concentrate on its warm absorber.

Markarian 478 is the prototype narrow-line Seyfert 1 galaxy. Based on its spectra taken by the FUSE, HST/FOS, and Kitt Peak Observatory 2m Telescope, we find a tendency that the emission lines of increasing ionization level show increasing excess flux at their blue wings and an increasing line peak velocity shift. This may indicate an outflowing component in the Broad-Line Region (BLR) where the ionization level increases with ejection velocity. In the mean time, the associated absorption lines are present on the blue wings of the high-ionization emission doublet O VI λλ1032, 1038 and Lyman β line. The physical condition of some absorbing components can be well constrained with the assistance of photoionization models. The flux ratios at the blue wings of emission lines of various ionization levels, as a function of outflow velocity, could also put important constraints on the physical condition of the outflowing components.

Our recent Chandra and XMM-Newton observations of the gravitationally lensed broad absorption line quasars (BALQSOs) APM 08279+5255 and PG 1115+080 have provided new insights into the structure of quasar outflows and the enrichment of their host galaxies by quasar winds (Chartas et al. 2002, 2003). Our spectral analysis of these observations suggests the presence of X-ray BAL material accelerated to relativistic velocities of up to ~ 0.4c, considerably larger than the observed velocities of the UV BAL absorbers in these objects. We present constraints on the quasar mass-outflow rates based on the observed relativistic outflow velocities and locations of the X-ray BAL material.

We discuss HI and optical evidence for ongoing ICM-ISM interactions in 6 Hi-deficient Virgo cluster spiral galaxies. One of the clearest cases is the highly inclined Virgo galaxy NGC 4522, which has a normal stellar disk but a truncated gas disk, and lots of extraplanar gas right next to the gas truncation radius in the disk. Unusually strong HI, Hα and radio continuum emission are all detected from the extraplanar gas. The radio continuum polarized flux and spectral index peak on the side opposite the extraplanar gas, suggesting ongoing pressure by the ICM. Four other HI-deficient edge-on Virgo spirals show evidence of extraplanar ISM gas or exhibit asymmetries in their disk HI distributions, but contain much less extraplanar HI than NGC 4522. Comparison with recent simulations suggests this difference may be evolutionary, with large surface densities of extraplanar gas observed only in early phases of an ICM-ISM interaction. In NGC 4569, the Hα image shows 2 effects of ICM pressure on the galaxy ISM. An anomalous arm of HII regions, possibly extraplanar, emerges from the edge of a truncated Hα disk. This resembles the arms seen in simulations which are formed by the combined effects of wind pressure plus rotation. An extended nebulosity near the minor axis, also in the NW, is interpreted as a starburst outflow bubble disturbed by ICM wind pressure.

We investigate the process of ram pressure stripping by means of numerical simulations with a 2D hydrodynamical code. We present some first results of a set of simulations with varying galaxy velocities and ICM densities. We find that in typical cluster core environments disk galaxies lose a substantial amount of their gas, whereas in the outskirts of galaxy clusters the mass loss is quite small. Furthermore, the gas loss happens in two phases: In the initial phase gas is pushed out of regions where the ram pressure overcomes the gravitational restoring force; most of the overall gas loss happens in this phase. Afterwards the Kelvin-Helmholtz instability leads to a further mass loss at a small rate, that could be important on long timescales.

The λ6 cm radio continuum emission from the barred galaxy NGC 2442 displays several unusual features that are probably due to the interaction of the galaxy with the intergalactic medium.

The stellar abundance pattern of neutron-capture elements such as Ba is used as a powerful tool to infer how star formation proceeded in dwarf spheroidal (dSph) galaxies. It is found that the abundance correlation of Ba with Fe in stars belonging to dSph galaxies have a feature similar to the Ba-Fe correlation in Galactic metal-poor stars. The common feature of these two correlations implies that dSph stars formed from gas with a velocity dispersion of ~26 km s−1. This velocity dispersion together with the stellar luminosities strongly suggests that dark matter dominated dSph galaxies. The tidal force of the Milky Way links this velocity dispersion with the currently observed value ≤ 10 km s−1 by stripping the dark matter in dSph galaxies. We also investigate the ram pressure exerted on the gas in ω Cen. It is found that the ram pressure is not strong enough to strip the gas but is expected to induce a bulk motion of the gas during the star formation epoch which is compatible with the recent observed finding and then the remaining gas after the star formation is likely to be stripped due to the gradual increase in the gas density in the forming Galactic disk.

We report here the results of deep optical spectroscopy of the very extended emission-line region (VEELR) found serendipitously around the Seyfert 2 galaxy NGC 4388 in the Virgo cluster. The Hα recession velocities of most of the filaments of the region observed are highly blue-shifted with respect to the systemic velocity of the galaxy. The velocity field is complicated, and there seem to be several streams of filaments ranging from ~ −100 km s−1 to ~ −700 km s−1 with respect to the systemic velocity of the galaxy. The emission-line ratios of the VEELR filaments are well explained by power-law photoionization models with solar abundances. In addition to photoionization, shock heating probably contributes to the ionization of the gas. We conclude that the VEELR was formerly the disk gas of NGC 4388, which has been stripped by ram pressure due to the interaction between the hot intra-cluster medium (ICM) and the galaxy.