From a Chandra survey of nine interacting galaxy systems the evolution of X-ray emission during the merger process has been investigated. From comparing LX/LK and LFIR/LB it is found that the X-ray luminosity peaks ∼300 Myr before nuclear coalescence, even though we know that rapid and increasing star formation is still taking place at this time. It is likely that this drop in X-ray luminosity is a consequence of outflows breaking out of the galactic discs of these systems. At a time ∼1 Gyr after coalescence, the merger-remnants in our sample are X-ray dim when compared to typical X-ray luminosities of mature elliptical galaxies. However, we do see evidence that these systems will start to resemble typical elliptical galaxies at a greater dynamical age, given the properties of the 3 Gyr system within our sample, indicating that halo regeneration will take place within low LX merger-remnants.

In this paper, we will review recent progress made in the understanding of cosmic silicates and the experimental characterization of relevant analogue materials. We will introduce the main structural properties of silicates. Then we will discuss recent infrared observations with a special emphasis on protoplanetary disks and AGNs. In the experimental section we will describe the optical properties of silicate grains. Here we will concentrate on fundamental optical data and the dependence of the optical behavior on particle shape and temperature.

The central controversy over whether or not ultraluminous X-ray sources (ULXs) contain a new “intermediate-mass” class of black holes (IMBHs) remains essentially unresolved. Indeed, whilst many recent X-ray spectroscopy results find evidence for a cool (100–200 eV) accretion disc – the expected signature of a ${\sim} 1000$ M$_{\odot}$ IMBH – in ULX spectra, most of the circumstantial evidence (a combination of multiwavelength counterparts, theoretical modelling and the behaviour of accreting black holes in our own Galaxy) argues that the black holes underlying ULXs could be substantially less massive. I will present a new analysis of the deepest XMM-Newton observations of ULXs that directly addresses their underlying nature. This includes the results of a new 100-ks observation of the archetypal ULX Holmberg II X-1. Though a slight soft excess in its X-ray spectrum can be fitted by a cool accretion disc model, a rigorous analysis of the temporal data shows that the black hole cannot be larger than ${\sim}100$ M$_{\odot}$. Interestingly, we find evidence that the putative accretion disc corona is cool and optically thick in this source, unlike most Galactic binaries. We have also undertaken a detailed spectral analysis of the next 12 best ULX datasets in the XMM-Newton archive. Using physically self-consistent spectral modelling we show that whilst all the ULXs show possible cool accretion discs, the majority of these ULXs appear dominated by an optically-thick Comptonising medium. I will argue that this is evidence that most (though not necessarily all) ULXs contain black holes that are at most a few tens of solar masses in size.

Disks surrounding young stars play a fundamental role in the formation of stars and planets. Accretion through disks is believed to be responsible for the build up of stellar masses, and the gas and dust in disks is a reservoir for the potential formation of planets. As a result, one of the motivations for observing the inner regions of disks (i.e., the region within 10 AU) is to obtain clues to the processes that govern how stars and planets form. Significant progress has been made over the last decade in probing the inner regions of gaseous disks through the use of infrared molecular transitions. I discuss the observational tools that are currently available to study the gaseous component. These tools can be used to explore the evolution of gas in the inner disk and thereby help us to understand the processes of giant and terrestrial planet formation. These same tools may also be used to place constraints on the physical mechanisms that drive the disk accretion process.

We report on analysis of the poorly studied source 2RXP J130159.6-635806 at different epochs with ASCA, BeppoSAX, XMM-Newton and INTEGRAL. The source shows coherent X-ray pulsations at a period ${\sim}700$ s with $\dot{\nu}\sim 2\times 10^{-13}$ Hz s$^{-1}$. A broad band (1–60 keV) spectral analysis of 2RXP J130159.6-635806 based on almost simultaneous XMM-Newton and INTEGRAL data demonstrates that the source spectrum is an absorbed power law with a photon index $\Gamma\sim 0.5-1.0$ and a cut-off energy of ${\sim}25$ keV. We also report on the identification of the likely infrared counterpart to 2RXP J130159.6-635806. The interstellar reddening does not allow us to strongly constrain the spectral type of the counterpart. The latter is, however, consistent with a Be star, the kind of which is often observed in accretion powered X-ray pulsars.

Microquasars are sources of very high-energy gamma-rays and, very probably, high-energy gamma-ray emitters. We propose a model for a jet that can allow to give accurate observational predictions for jet emission at different energies and provide with physical information of the object using multiwavelength data.

We have used Chandra archival observations of 19 galaxies hosting LINERs to explore the morphology and source population of their inner kiloparsec. Our goal was, in general, to determine the power source behind their nuclear X-ray emission and, in particular, to investigate the presence of an AGN. We find an AGN in 12 of the 19 galaxies in the sample. We also find that diffuse, thermal emission is common with properties very similar to what is found in normal galaxies. In 10 out of the 19 galaxies, the diffuce emission dominates the nuclear X-ray power. The X-ray point-source populations were studied by producing cumulative luminosity functions and their properties are also similar to what is found in normal galaxies.

A summary is given of the presentations delivered at IAU Symposium 231.

IGR J17252–3616 is the hard X-ray counterpart of EXO 1722–363. The regular monitoring by INTEGRAL shows that IGR J17252–3616 is a persistent source with an average count rate of $\sim$6.4 mCrab in the 20–60 keV energy band. A follow-up observation with XMM-Newton showed that the source is located at R.A. (2000.0) $=17^{h}25^{m}11.4^{s}$ and Dec. $=-36{\hbox{$^\circ$}} 16 {\hbox{$^\prime$}} 58.6 \hbox{$^{\prime\prime}$}$ with an uncertainty of $4 \hbox{$^{\prime\prime}$}.

The source is a binary X-ray pulsar with a spin period of 413.7 s. The spectral shape is typical for an accreting pulsar except that a huge intrinsic absorption and a cold iron fluorescence line are detected. The absorbing column density and cold iron line do not vary with the pulse period. The observations suggest that the source is a wind-fed accreting pulsar accompanied by a supergiant star.

With the notable exception of those originating on the Moon and Mars, all known meteorites are pieces of objects in the asteroid belt. As such, they have recorded a succession of chemical processes, starting from reactions in the interstellar medium (ISM), followed by reactions that accompanied the formation and evolution of the early solar system, and culminated with reactions during aqueous alteration in the meteorite parent bodies. One of the challenges in meteorite research is to decipher this record and to learn about interstellar formation processes as well as to conditions in the early solar system. The rare class of carbonaceous chondrites contains up to 5% by weight of organic carbon, most of which is locked in an insoluble macromolecular material and only about 20% of it is in the form of distinct organic compound classes. The molecular and isotopic data of these organic compounds clearly show an interstellar heritage, but a fraction of these precursors were later modified. For example, the amino acids were probably formed inside the meteorite parent body during the aqueous alteration period from simple molecules such as HCN, NH3 and carbonyl compounds. However, the CI type carbonaceous chondrites contain a significantly distinct amino acid composition, indicating that there may be other synthetic processes involved. Polycyclic aromatic hydrocarbons (PAHs) are probably the most abundant form of organic carbon in the gas phase in the ISM. PAHs are among the most abundant organic compounds in carbonaceous meteorites, and they have been shown to have a presolar origin. A fraction of these PAHs are present in an extractable form, while the rest is part of the insoluble macromolecular matter. Progress is being made in the understanding of the evolution of this material in relation to aqueous alteration and oxidation. Although the potential of cometary meteorites cannot be ruled out, no such macro-meteorite has been recognized in the meteorite collections. Therefore, the organic composition of comets has been inferred mostly from astronomical observations. Future in-situ investigation of comets with spacecraft such as Rosetta will deliver new data on their organic composition, in particular the non-volatile fraction. However, in order to understand the contributions of different formation processes in primitive solar system objects, the analysis of the organic composition of meteorites remains essential.

In this review the present status of molecules in circumstellar envelopes of AGB stars is presented. Emphasis is put on the determination of abundances, and estimates of their uncertainties, from an observational point of view. Despite an impressive number of circumstellar species detected, about 60, there remains much work before general conclusions can be drawn. In particular, sophisticated radiative transfer modelling of circumstellar line emission must be done. This requires a detailed knowledge of the stellar and circumstellar properties, as well as basic molecular physics/chemistry data.

We present here the results of new XMM-Newton observations of the PSR B1259–63 system during the beginning of 2004, as the pulsar approaches the disc of the Be star. We combine these results with earlier X-ray data from BeppoSAX, XMM-Newton, and ASCA. The X-ray light curve looks similar to the radio light curve with a rapid increase in the flux around the time of the disc crossing. This supports a model in which the X-ray emission from the system is due to inverse Compton scattering of the pulsar wind relativistic particles with moderate Lorentz factor $\gamma \sim 10$–100 on the Be star soft photons.

We report on astrophysical aspects of fully innovative very wide–field X-ray telescopes with high sensitivity. They are expected to contribute essentially to study of various astrophysical objects such as AGN, SNe, Gamma-ray bursts (GRBs), X-ray flashes (XRFs), galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc.

The ESA observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory) is dedicated to fine imaging and spectroscopy in the energy range 15 keV to 10 Mev with concurrent X-ray (3-35 keV) and optical monitoring. It was launched on October 17, 2002 and has been succesfully operating ever since. Its two main instruments the spectrometer SPI – optimized for high resolution spectroscopy – and the imager IBIS – optimized for for high resolution imaging – are complemented by the X-ray monitor JEM-X and the optical monitor OMC. All the high energy instruments use coded mask techniques, allowing imaging in the gamma-ray range and combining wide fields of view with high spatial resolution. The presentation gives an overview of the unique properties of INTEGRAL.

Deep field observations are an essential tool to probe the cosmological evolution of galaxies. In this context, X-ray deep fields provide information about some of the most energetic cosmological objects: active galactic nuclei (AGN). Astronomers are interested in detecting sufficient numbers of AGN to probe the accretion history at high redshift. This talk gives an overview of the knowledge resulting from a highly complete soft X-ray selected sample collected with ROSAT, XMM–Newton and Chandra deep fields. The principal outcome based on X-ray luminosity functions and space density evolution studies is that low–luminosity AGN evolve in a dramatically different way from high–luminosity AGN: The most luminous quasars perform at significantly earlier cosmic times and are most numerous in a unit volume at cosmological redshift $z\sim2$. In contrast, low–luminosity AGN evolve later and their space density peaks at $z\sim 0.7$. This finding is also interpreted as an anti–hierarchical growth of supermassive black holes in the Universe. Comparing this with star formation rate history studies one concludes that supermassive black holes enter the cosmic stage before the bulk of the first stars. Therefore, first solutions of the so-called hen–egg problem are suggested. Finally, status developments and expectations of ongoing and future extended observations such as the XMM–COSMOS project are highlighted.

We present models for gamma-ray production in microquasars and we propose them as possible parent populations for different groups of EGRET unidentified sources. These models are developed for a variety of scenarios taking into account several possible combinations, i.e. black holes or neutron stars as the compact object, low mass or high mass stellar companions, as well as leptonic or hadronic gamma-ray production processes.

The role of high spectral and spatial resolution spectroscopy in understanding the evolution of the gaseous component of circumstellar accretion disks is described. Millimeter-wave emission lines from trace constituents such as CO, CN, HCO+, and HCN can be used to probe the kinematic and physico-chemical properties in the near-surface regions of disks beyond 50–100 AU, but, thanks to extensive depletion in the midplane, they are not a reliable proxy for the disk mass. For the special case of nearly edge-on circumstellar disks, the resulting ices can be directly observed through mid-infrared spectroscopy, using ground based facilities or spacecraft (cf. Najita, this volume). Emerging and planned millimeter-wave → THz arrays will possess sufficient sensitivity and resolution to probe much closer to the central star and to search for prebiotic compounds such as those detected in comets, meteorites and interplanetary dust particles.

While the physical characterization of near-Earth objects (NEOs) is progressing at a much slower rate than that of discovery, a substantial body of thermal-infrared data has been gathered over the past few years. A wide variety of taxonomic classes in the NEO population have now been sampled by means of thermal-infrared spectrophotometric observations. The resulting albedo information, together with the distribution of taxonomic types from spectroscopic investigations and the rapidly increasing catalog of orbits and absolute magnitudes derived from NEO search programs, such as LINEAR, facilitates more accurate estimates of the size distribution of the NEO population and the magnitude of the impact hazard. Despite our rapidly increasing knowledge of the NEO population, many questions and uncertainties remain, such as: How does the albedo distribution of NEOs compare with that of main-belt asteroids, and does space weathering play a role? How does the surface structure and regolith coverage of NEOs vary with size and taxonomic type? What fraction of NEOs are extinct comets? A property of particular interest is the surface thermal inertia of small asteroids, which is an indicator of the presence or lack of a thermally-insulating surface layer. Large asteroids can accumulate regolith, but can very small asteroids retain thermally-insulating collisional debris or at least a dust layer? Knowledge of thermal inertia is important for accurate calculations of the Yarkovsky effect, which can significantly influence the orbital evolution of potentially hazardous NEOs, and for the design of instruments for lander missions. Contrary to earlier expectations, evidence appears to be accumulating that even sub-kilometer asteroids often have a significant thermally-insulating surface layer. Recent results from thermal-infrared investigations of NEOs are reviewed and implications for the surface properties of small asteroids discussed.

I review here the current ideas regarding the origin, evolution, and physical nature of hot diffuse gas in normal, starburst, interacting and merging galaxies, using recent X-ray observations with XMM-Newton and Chandra. Many types of diffuse X-ray structures, including winds, bubbles, halos, chimneys and fountains, can be formed in galaxies, and can enrich the intergalactic medium with mass, energy and metals. This has profound implications as regards galactic formation and evolution, and the enrichment and evolution of galaxy groups and clusters.

The proliferation of X-ray astronomy missions over the last 10 years has had a major impact on our knowledge of Galactic X-ray binaries. More recently, Chandra and XMM-Newton have provided a dramatically improved census of extra-galactic X-ray binaries. In this talk I will provide an overview of the various populations and observational properties of X-ray binaries in our Galaxy, in an effort to “set the scene” for a comparison with their extra-galactic counterparts.