I will discuss the connection between the luminosity function of a population of high-mass X-ray binaries in a galaxy and the star formation rate in the this galaxy. The understanding of this connection provides on the one hand an independent measure of an important galaxy property, and on the other hand new insights into populations of high-mass X-ray binaries. In particular, observations with the Chandra X-ray telescope are uniquely suited to investigate the X-ray part of this connection and I will present examples of this.

We review progress in the area of the modelling of shocks in molecular clouds. In particular, we consider what has been learnt about shock structure evolution in situations where the steady-state assumption is no longer valid. We discuss the interpretation of the observed water abundance from SWAS, Odin, and ISO. We also consider the erosion of grains in shocks as well as the effect of the presence of grains on shock structure.

We present time-resolved spectroscopy from the January 2005 outburst of the X-ray nova XTE J1118+480. X-ray observations show this outburst to be about half as bright as the previous outburst in 2000. This suggests that the accretion rate was lower than that in the 2000 outburst. Our spectroscopic analysis shows that the emission from the H$\alpha$ line occurs at a higher velocity in the recent outburst compared with the 2000 outburst, more consistent with quiescence/near-quiescence values. This is surprising, considering the $\sim$5 magnitude brightening of the accretion disk relative to its quiescent state.

We consider the feasibility of detecting neutron star companions to High Mass X-ray Binaries (HMXBs) using astrometric techniques, specifically for accuracies expected for the upcoming Gaia satellite. The direct determination of orbital parameters of HMXBs will increase the census of measured neutron star masses.

The presence of large organic species in interstellar gas has important implications for the origin of life and pre-biotic chemistry. Accurate identifications of such molecules, however, are problematic in molecular clouds. There are many reasons for such difficulties. One is that the spectral density is very high in objects where the chemistry is sufficiently complex to produce such species—at least 10 lines per 100 MHz in Sgr B2(N), for example, at 3 mm, at a sensitivity of 10 mK peak-to-peak. Hence, the possibility of chance coincidences is large. Another reason is the presence of many large organic molecules at relatively high temperatures; these large asymmetric tops have vast numbers of favorable transitions under these conditions, including those originating from low-lying vibrational states. Confusion and blending of transitions of one large molecule with those of another add to the risks of an inaccurate identification.

A case in point is that of glycolaldehyde, CH$_2$OHCHO. In order to confirm the identification of this molecule in Sgr B2(N), we searched for its most favorable transitions in the 2 and 3 mm windows, spanning the energy range of ${\sim}$10–100 K—a total of 43 individual transitions. Of all these lines, only seven were not heavily blended or contaminated by other molecules, i.e. so-called “clean” features. Emission, however, was visibly detected at 34 of the other transitions, but one transition was clearly absent. The “missing” line corresponds to a weak transition originating in the $K_a =$ 3 ladder, and its absence is consistent with the other detected features. Based on the clean features only, glycolaldehyde has a $V_{LSR} = 61.7 \pm 1.5$ kms$^{-1}$ and $\Delta V_{1/2} = 7.8 \pm 1.8$ kms$^{-1}$ with intensities consistently in the range $T_R^* \sim 20-70$ mK. Given these data, the identification of glycolaldehyde is 99.9% secure. A rotational diagram from this data set yields a column density of $N_{tot} \sim 6 \times 10^{13}$ cm$^{-2}$ for CH$_2$OHCHO—roughly a factor of 27 less than that of H$_2$CO. These data illustrate the problems and subtleties in identifying large organic molecules in space.

Understanding deuterium fractionation is currently one of the greatest challenges in astrochemistry. In this contribution deuteration experiments of the series CH$_n^+$, n=2–5, in a low temperature 22-pole ion trap are used to systematically test a simple chemical rule predicting which molecular ion undergoes deuterium exchange in collisions with HD. CH$_4^+$ turns out to be a problem case, where prediction fails. The method of laser induced reaction (LIR) is used to determine the population ratio of the lowest ortho-to-para states of H$_2$D$^+$ relaxed in collisions with H$_2$. Preliminary results indicate that the ortho-to-para ratio of H$_2$D$^+$ is substantially reduced in para-H$_2$. This points at the important role of nuclear spin in deuterium fractionation, in particular at the destruction of ortho-H$_2$D$^+$ in collisions with ortho-H$_2$. More systematic LIR experiments are needed for a chemical model of deuterium fractionation including state-to-state modifications of the species involved.

Population studies of faint X-ray sources (e.g. galaxies, AGN, $\gamma$-ray bursts and their afterglows) have become more and more common. The problem of obtaining an average spectrum in the rest-frame of the sources is non-trivial. We show that conventional methods for averaging low signal-to-noise X-ray spectra, when applied to sources at different redshifts, result in a mean rest-frame spectrum that can exhibit artificial features. These include the broadening and weakening of emission/absorption lines, a broad dip in the continuum above an emission line, and a spectral hardening at the highest energies. All of these effects have been observed in real data and have been given fairly weighty astrophysical and/or cosmological interpretations. We present a new method of averaging which considerably reduces the severity of the problems.

The paper focuses on collisional excitation rates of molecules by He and H2 relevant to the interstellar medium. It discusses currently available data, presents very recent work and outlines new work being carried out by various teams.

We present a coupled dynamical and chemical model for collapsing pre-stellar cores (Li et al. 2002; Shematovich et al. 2003a,b; Pavlyuchenkov et al. 2003). It treats the dynamics of thermally and magnetically supported cores in 1D, with an extended chemical network incorporated. The latest version of the model includes UV-irradiation of the core envelope. We have also developed a 2D Monte Carlo model of radiative transfer to compute molecular line profiles for comparison with observations.

The model allowed us to constrain evolutionary scenarios for collapsing pre-stellar cores, to calculate molecular line profiles from the spatial distribution of chemical species and the velocity field, and to characterize the chemical properties of dense cores.

We have determined line profiles along multiple lines of sight through a given pre-stellar core. This allowed us to compare model predictions with the observational maps of molecular lines available for L1544 and other well studied cores. The comparison of synthetic and observed line profile maps contributed to the understanding of the velocity field and pattern of chemical differentiation observed in individual cores.

During the first year in operation, INTEGRAL has detected more than 28 new bright sources which emit the bulk of their emission above 10 keV. Follow-up observations of a subset of these sources in the X-ray band with XMM-Newton indicate that 80% of them are very strongly absorbed. More than half of these absorbed sources show strong pulsations with long periods ranging from 139 to 1300s, i.e., they are slow X-ray pulsars. Many of these new sources are super-giant high-mass X-ray binaries (HMXB) in which the stellar wind of the companion star is accreted onto the compact object. The large local absorption in these new sources can be understood if the compact objects are buried deep in their stellar winds. These new objects represent half of the population of active super-giant HMXB.

There are three types of energy sources that affect comet nuclei and may render them active: thermal – solar radiation, nuclear – radioactive decay, and gravitational – through collisions and tidal forces. These sources give rise to processes that, in turn, may release, absorb or transport energy: sublimation or recondensation of volatiles, crystallization of amorphous ice, heat diffusion and advection, gas flow through the porous nucleus. Each of these sources and processes has its own characteristic time scale (or rate) and these may differ by many orders of magnitude. It is the competition between various processes and the interaction between them – as one triggers the other, or else impedes it – that determine the activity pattern and the internal structure of a comet nucleus. Examples of such interactions and their outcome are presented, such as apparently sporadic activity at large heliocentric distances, obtained from numerical simulations of the behavior and evolution of comet nuclei. Confrontation of modeling results with observations provides feedback and constraints for the assumptions and parameters on which models are based. Adjusting the latter to match observations reveals properties of the nucleus that are otherwise inaccessible (except for in situ measurements by space missions). However, the interpretation of observations, such as production rates in relation to nucleus abundances, may be misleading. It is shown that monitoring production rates over the active part of a periodic comet's orbit may lead to conclusions regarding the composition and structure of the nucleus.

Understanding the molecular phase of the ISM in starburst and active galaxies is important for the modelling of the onset and evolution of their nuclear activity. Observations of high density gas tracers such as HCN, HNC, HC3N, HCO+ and CN are essential for probing physical and chemical conditions of the dense, star-forming gas. These tracers show great potential as indicators of the evolution of star formation as well as probes of X-ray illuminated molecular gas around an active galactic nucleus (AGN). In particular, towards the inner kpc of luminous and ultra luminous galaxies will molecular line ratios prove useful as diagnostic tools, since optical and even near infrared starburst tracers are difficult to apply in these highly obscured regions.

The Swift Gamma-ray Burst Explorer mission, launched on 2004 November 20, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. The satellite carries three instruments: a new-generation wide-field gamma-ray (15–150 keV) detector that detects bursts, calculates 1–4 arcmin positions, and triggers autonomous spacecraft slews; a narrow-field X-ray telescope that gives 5 arcsec positions and performs spectroscopy in the 0.2 to 10 keV band; and a narrow-field UV/optical telescope that operates in the 170–600 nm band and provides 0.3 arcsec positions and optical finding charts. In the first 8 months of the mission (until the end of July 2005), Swift detected 54 GRBs performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. Swift has already collected a rich trove of early X-ray afterglow data and some interesting features are emerging. In particular early afterglow signatures reveal valuable and unprecedented information about GRBs, including the prompt emission – afterglow transition, GRB emission site, central engine activity, forward-reverse shock physics, and the GRB immediate environment.

The association of “long” Gamma-Ray Bursts (durations > 2 seconds) with peculiar Type Ic supernovae suggests strongly that this type of GRB is produced by the collapse of the rapidly rotating core of an initially very massive star to a black hole. At the time of collapse the star has lost its hydrogen-rich envelope and the GRB is thought to be produced by a collimated relativistic jet of matter ejected along the star's rotation axis. The angular momentum constraints for producing such a “collapsar” or “hypernova” suggest that the GRB-producing core collapses constitute only a small fraction of all core collapses of massive stars. As to the short-duration GRBs (< 2 seconds), which make up about one third of all GRBs, the most favoured model is that of the coalescence of a double neutron star or of a neutron star-black hole binary. Also these events are expected to be very rare, having a frequency of at most one event per hundred thousand years for a galaxy like our own. Due to the collimation of the relativistically ejected matter, the observable frequency of GRB events will, like in the case of the “long” bursts, be at least a factor hundred smaller.

The study of the molecular gas in quasars and submillimeter galaxies at high redshift has significantly progressed during the last few years. From the current detection of CO emission in 37 sources spanning a range in redshift from $1<z<6.4$ with, in some cases, the measurement of a series of CO rotational transitions, it is possible to constrain the physical conditions of the massive ($\ge 10^{10} \, M_\odot$) reservoirs of gas in these objects. This review will present the current status of the studies of molecular gas in high-$z$ sources, detail the physical conditions which pertain in these systems, which are scaled-up versions of the local ULIRGS, and discuss the searches in high-$z$ sources for species other than CO, including the fine structure lines of neutral carbon and the recent detection of the redshifted [CII] emission line in the $z=6.4$ quasar J 1148+5251. These results hold great promise for the study of galaxy formation and their evolution with redshift. This review will conclude by outlining the expected progress in the field, in particular when future instruments such as ALMA will be operational, which will enable to study the astrochemistry and its evolution in the early universe.

The massive star clusters identified by S. Larsen are compared to the available Chandra observations of face-on spiral galaxies. In each galaxy, a few percent of the Larsen-identified clusters match X-ray-emitting point sources. An additional few match knots of emission in the diffuse emission. The cluster properties are examined to ascertain whether massive star clusters are X-ray sources.

We have discovered a number of nonthermal X-ray features within central 40 pc region of the Galactic center by analysing 600-ksec observations of Chandra archival data. Most of the detected X-ray structures exhibit small-scale knot-like morphologies and their spectra are well reproduced by single hard power-law with photon indices of 1-2. Among them, the most outstanding features are the three X-ray knots which are aligned on a straight line from the potition of Sgr A* to north-northwest direction. The X-ray properties of these knots lead us to suspect that they are X-ray jets ejected from Sgr A* in the recent past. In addition, we have obtained an indication that the summed flux of nonthermal diffuse X-rays within 30 pc of the GC seems to be smoothly connected to the 20-100 keV flux detected with INTEGRAL IBIS/ISGRI. These results suggest that the origin of GC hard X-rays (or High energy Gamma-rays) is not (or partly) from the Galactic nucleus.

The Very Energy Radiation Imaging Telescope Array System (VERITAS) in its first phase of operation will consist of an array of 4 Imaging Atmospheric Cherenkov Telescopes (IACTs) arranged in a ‘Mercedes’ star configuration. To be located at a high, dark site in Southern Arizona the full array is expected to see first light in October 2006. In February of 2005 the first VERITAS telescope achieved first light at a temporary location near to the final site. This poster summarises the status of the VERITAS instruments as of summer 2005.