LAMOST sky survey for the structure of the Milky Way galaxy

Main Colloquium
Prof. Licai Deng
ORATED
National Asyronomical Observatories, Beijing

The Chinese key scientific project, LAMOST, has concluded its construction phase, and is now under going technical commissioning. This is a dedicated survey facility which will carry out a full sky spectral survey of stellar and galactic source. Scientific program of LAMOST will be started in 1 year or 2 from now. LAMOST is a reflecting telescope with a horizontal layout, aperture diameter 3.6-4.8 m, field of view of 20 square degrees and 4000 fibers evenly distributed on the focal plane of 1.75m, with each fiber driven by 2 independent motors. In this talk, I will cover instrument specifications, site conditions, scientific potential in Galactic structure studies, as well as the latest status of the project.

High Resolution Studies of AGN - A radio flare in CTA 102 as test of shock-in-jet model

Special Colloquium
Christian M. Fromm
ORATED
MPIfR

We test the shock-in-jet model and the hypothesis of an over-pressured jet on the historical 2006 radio flare in CTA 102. For our analysis we used single-dish observations as well as three multi-frequency VLBI observations. From the light curve analysis we can identify the three different radiation loss stages, where the synchrotron stages shows a unexpected double peak structure. The evolution of the spectral parameters along the jet during the flaring event are extracted from VLBI observations and confirm our assumed model. The double peak structure can be explained by a change in the viewing angle and leads to a Doppler boosting of the flux densities around 2006.1.

Dust polarization and magnetic field in high mass star formation - arcsecond view

Special Colloquium
Dr. Ya-Wen Tang
ORATED
Academia Sinica, Astronomy and Astrophysics, Taiwan

Magnetic fields in star formation process are always been invoked to explain the slow process of star formation, to explain the low formation rate, and to transfer the angular momentum outward in the accretion disk. However, it is difficult to trace the B field strength and geometries of field lines due to its weak signal. Polarized emission from dust grains can be used to study the B field in the plane of sky. The emission at mm and submm wavelengths is optically thin and therefore, is good to trace the dense regions. With the capabilities of current functioning interferometers SMA, we have studied the B field geometries in several massive star formation regions. High angular resolution B field maps are important when studying the role of the B field in the star forming cores. To analyze the role of B field, we also need to know the knematics of the molecularcloud and to link the field geometry with larger scale field. The role of B field varies with the evolutionary stages of the cetral stars and also with size scales of interest. In this talk, I will present our case studies toward three massive star forming regions.

Chemical modelling of dark cores and its application to star formation

Main Colloquium
Dr. Julia Roberts
ORATED
Centro de Astrobiologia, Madrid

The early stages of star formation are extremely difficult to observe because they occur hidden inside dense, dark molecular cores. Chemical models are useful tools for probing the physical conditions and processes occurring inside such cores. A full understanding of the chemical network can allow us to predict time dependent chemical abundance profiles of dark cores, as well as predicting molecules which can act as tracers for various physical processes. In this talk I will give an introduction to the chemistry of dark cores, and show the results of a recent project investigating the possibility of using chemistry to diagnose different models of core collapse.

Formaldehyde Masers in the Galaxy

Main Colloquium
Prof. Peter Hofner
ORATED
New Mexico Tech & NRAO, Socorro, NM, USA

Formaldehyde (H2CO) is one of the most abundant insterstellar molecules and is easily detected across the Galaxy in absorption against galactic and extragalactic continuum sources. Maser action in this molecule was detected in 1974 with the 100m Effelsberg telescope, and despite a number of dedicated searches in subsequent decades only 2 more sources were discovered until recently. In this talk I will describe our search campaigns for new H2CO masers which lead to the discovery of 6 new sources since 2004. In the second part of the talk I will focus on the source IRAS18566+0408 in which we have discovered periodic bursts of the H2CO maser.

Puzzles of the microwave sky

Main Colloquium
Dr. Dominik Schwarz
ORATED
Universität Bielefeld

While observations of the cosmic microwave sky confirm the so-called concordance model of cosmology on small and intermediate angular scales, there seems to be disagreement at the largest scales. The microwave sky is uncorrelated at scales above 60 deg, contrary to expectations for a dark energy dominated universe. On top of that, the quadrupole and octopole seem to be aligned with the orientation and motion of the solar system. The origin of these anomalies remains a puzzle, some attempts to resolve this puzzle are presented.

The space distribution of nearby star-formation

Special Colloquium
Prof. Laurent Loinard
ORATED


Using the excellent astrometry capabilities of the Very Long Baseline Array, we have measured the trigonometric parallax (and the proper motions) of a number of young stars in several nearby star-forming regions with an accuracy better than a few percents. This represents an improvement by one or two orders of magnitude over previous determinations. In particular, we have found that the distance to the core of Ophiuchus is 120pm4.5 pc, and we have confirmed that the mean distance to Taurus is 140 pc. Our data also allows us to obtain a rough determination of the 3D structure of the regions under study. In the case of Taurus, we have shown that the total extent of the complex along the line of sight is about 30 pc, the eastern portion being on the far side and the region around L1495 on the near side. In this talk, after presenting the results themselves, I will describe several new constraints for the formation and early evolution of stars that these data provide, focusing in particular on pre-main sequence evolutionary models. I will end my talk by mentioning preliminary results in other regions (particularly Serpens and Cepheus), as well as longer-term prospects.

Galactic dynamos and magnetic helicity fluxes.

Special Colloquium
Dr. Sharanya Sur
ORATED
ITA, Heidelberg University

Conservation of magnetic helciity is regarded as a key constraint in the evolution of large-scale magnetic fields. One of the consequences of helicity conservation is that, it leads to a suppression of large-scale dynamo action due to the current helicity of the growing small-scale field. The suppression is catastrophic in the sense that the large-scale field is quenched to negligible values well before it can be amplified to observable strengths. Helicity fluxes across the boundaries of the disc has been identified as a possible mechanism to shed small-scale magnetic helciity and prevent such a quenching. The speaker will discuss a simple semi-analytical model of nonlinear mean-field galactic dynamos incorporating magnetic helciity fluxes. The simplicity of the model allows for a deeper insight into the role and interaction of various mechanisms and also helps to extensively explore the parameter space. The efficiency of the galactic dynamo action facilitated by helicity fluxes will be demonstrated.

The Expanded Very Large Array

Special Colloquium
Dr. Rick Perley
ORATED
NRAO, Socorro

The EVLA project is a $90M upgrade of the Very Large Array which will multiply its scientific capabilities tenfold or more. Begun in 2000, the project is now nearing completion – on time, on spec, and on budget. All antennas will be upgraded to modern standards by mid-2010, the new WIDAR correlator will replace the old correlator in early 2010, and all receiver installations will be completed by the end of 2012. These upgrades will provide scientists with complete frequency coverage from 1 to 50 GHz, combined with unprecedented sensitivity and flexibility. In this talk I will review the status of the project and the unique observational capabilities that the EVLA will soon offer. A subset of these new capabilities will be available to all observers, beginning early in 2010 via the nascent OSRO and RSRO programs, which I will describe in detail. The array’s capabilities will rapidly rise over the following two years, following a growth path that is now being defined, and which depends to some extent on user-defined priorities.

Inefficient accretion: The hidden power in our universe?

Main Colloquium
Elmar Koerding
ORATED
MPIfR

Accretion can be the most efficient source of energy in the universe, powering Quasars as well as X-ray binaires (XRBs) and also Gamma-ray bursts. While the bright representatives can be highly spectacular, the vast majority of accreting sources show very low accretion rates. In theses sources one assumes that the accretion is happening inefficiently, making their accretion flow dim and hard to detect. However, most of those sources do show strong jets. I will discuss the evidence we have for such inefficient accretion first in XRBs and then in Active Galactic Nuclei. I will show that the kinetic power originating in the jet dominates the total power output in most cases and the cumulative power may exceed those of the strongly accreting objects. Scaling relations between sources of different mass will be discussed as well as their applications.

Chemical Evolution from Pre-Stellar Cores to Circumstellar Disks

Special Colloquium
Dr. Ruud Visser
ORATED
Leiden Observatory

The chemical composition of a molecular cloud changes dramatically as it collapses to form a low-mass protostar and circumstellar disk. Spherical models have always been used to model this chemical evolution, but they cannot describe the disk. I will present the first model that follows the entire chemical evolution from a pre-stellar core to a circumstellar disk in two dimensions. The model enables us to compute where the material accretes onto the disk (close to the star or far out) and how this affects the abundances of various key species. I will compare the model results to observational data. I will also discuss several applications of the model, such as the chemical origin of cometary material and the crystalline fraction of circumstellar silicate dust.

Status of the Sardinia Radio Telescope Project

Special Colloquium
Dr. Alessandro Navarrini
ORATED
Cagliari Astronomy Observatory, Italy

The Sardinia Radio Telescope (SRT) is a new general purpose, fully steerable 64 m diameter radiotelescope which will be capable to operate with high efficiency in the 0.3-116 GHz frequency range. The telescope is being built in the Sardinia island, Italy, and its completion is only few months away. The instrument is the result of a scientific and technical collaboration among three Structures of the Italian National Institute for Astrophysics (INAF). The radio telescope has a shaped Gregorian configuration with a 7.9 m diameter secondary mirror and supplementary Beam-WaveGuide (BWG) mirrors. With four possible focal positions (primary, Gregorian, and two BWGs), SRT will be able to allocate up to 20 remotely controllable wideband receivers. One of the most advanced technical features of the SRT is the active surface: the primary mirror will be composed by 1008 panels supported by digitally controlled electromechanical actuators to compensate for gravitational and thermal deformations. The status of the project will be presented.

Massive Star Formation in the Central Molecular Zone

Special Colloquium
Katharina Immer
ORATED
MIPfR Bonn

Since the centre of the Milky Way has a distance of only 8.5 kpc, it is one of the nearest locations to study massive star formation under the extreme conditions of galactic nuclei. The temperatures as well as the densities in the molecular clouds in the central molecular zone (CMZ) are very high. Furthermore, the clouds are exposed to strong tidal fields that can overcome the self-gravitation of the clouds. This raises the question if star formation in the CMZ is enhanced or hindered. I will present results of a multi-wavelengths study of massive star formation in the CMZ. The study is based on data from the Spitzer/GLIMPSE, MSX, and ATLASGAL programmes and a VLA survey at 1.4 GHz and results in a classification of the detected star forming regions according to their evolutionary stages. Furthermore, I will focus on a particular region of the CMZ, the so called Galactic Centre Dust Ridge. This region is located at a projected distance of 70 pc from the Galactic Centre and contains very massive dust clouds. I will discuss the star formation activity in this region.

Massive Galaxy and Black Hole Formation back to within 1 Billion Years after the Big Bang

Main Colloquium
Dominik Riechers
ORATED
MPIfR

I will present a study of the kinematics, star formation and cold gas properties of the highest redshift, most intensely star-forming galaxies with the (Expanded) Very Large Array, the Plateau de Bure Interferometer, and CARMA. Such detailed investigations are vital for our understanding of the formation and evolution of massive galaxies in the early universe. Molecular gas is the prerequisite material for star formation to occur. Also, gas dynamics can be used to trace the gravitational potential of galaxies, and thus, to obtain an independent estimate of the total mass in their central few kiloparsecs. Measuring the gas fraction is important to determine the evolutionary state of a galaxy, and to constrain gas depletion timescales and starburst lifetimes. The morphology and kinematics of the cold gas can also provide direct insight on the dominant mechanism responsible for the stellar buildup of these systems (i.e., major mergers vs. secular evolution). Determining the stellar and total mass of distant galaxies is important to investigate whether or not the (in the nearby universe) linear relation between stellar mass and black hole mass in early-type galaxies evolves with cosmic time and/or toward the high mass end. Such studies thus set the pace for future investigations of star formation and galaxy assembly out to the first galaxies that form in the universe, which will facilitate the capabilities of the upcoming Atacama Large (sub-)Millimeter Array (ALMA).

Properties of prestellar cores: cosmic ray ionization and non-LTE effects

Special Colloquium
Marco Padovani
ORATED
Arcetri

This talk is in two parts. In the first, I will present the results of a calculation of the cosmic-ray ionization rate and heating rate in a cloud of molecular hydrogen as function of the depth inside the cloud for different assumption on the incident cosmic-ray electron and proton spectra. In the second part I will show the results of a study of the abundance of C2H in prestellar cores, addressing in particular the non-LTE behaviour of the N=1-0 and N=2-1 transitions of this molecule. Based on these results, we compute improved rest frequencies and spectroscopic constants for C2H and its potential as a magnetic field probe.

MOND + 11eV sterile neutrinos: two wrongs do make a right`

Main Colloquium
Dr. Garry Angus
ORATED
University of Turino

For more than 25 years Milgrom’s Modified Newtonian Dynamics (MOND) has provided a stubborn alternative to dark matter in galaxies. However, even the fondest supporter must acknowledge how badly MOND fails to explain the dark matter in clusters of galaxies, and how much easier it is to explain the acoustic peaks of the cosmic microwave background with dark matter (as well as forming cosmic structure). Here I show that the simplest solution to all these problems comes in the form of an 11eV sterile neutrino, which was chosen to fit the CMB, but leads to some remarkable coincidences in the dark halos of galaxy clusters. Additionally I show the results from the Jeans analysis of the dwarf spheroidals of the Milky Way, which given their correlated positions around the Galaxy (possible tidal dwarf galaxies Kroupa, Theis & Boily 2005), make them one of the strongest motivations for MOND.

Magnetic fields in the post-recombination universe

Main Colloquium
Dr. Dominik Schleicher
ORATED
ALMA center Leiden

Magnetic fields appear ubiquitous in the local universe, and even normal galaxies at z=4 appear to have magnetic fields similar to the Milky Way. >From the epoch of recombination, an upper limit of 3 nG (comoving) exists from CMB measurements, but no direct measurement. The evolution between z=1100 and z=4 is therefore unclear. I will discuss the main scenarios concerning the generation of primordial fields and their further evolution, as well as their implications on the post-recombination era, the epoch of reionization and the formation of the first stars. As most of the gas is neutral at these early times, a non-ideal MHD treatment is required that takes into account the implications of magnetic energy dissipation via ambipolar diffusion, which may have profound implications for the chemical and thermal evolution of the gas. The increased thermal and magnetic pressure may delay the onset of reionization. Future radio telescopes like LOFAR or SKA can probe such scenarios in more detail by measuring the 21 cm power spectrum during the reionization epoch.

Studying Milky Way Galaxy with VLBI - from VERA to sub-mm VLBI

Main Colloquium
Dr. Mareki Honma
ORATED
NAOJ, Tokyo

I review our current activities at NAOJ to study Milky Way Galaxy with VLBI observations. First I will summarize the current status of VERA (VLBI Exploration of Radio Astrometry), which is a dedicated VLBI array to conduct high precision astrometry of Galactic maser sources such as star-forming regions and late-type stars. So far we have measured parallaxes and proper motions of about 20 maser sources and I will present some high lights of recent VERA’s outputs. In the second part of my talk, I will introduce our plan toward sub-mm VLBI observations using ASTE (Atacama Submillimeter Telescope Experiment) to directly image a black hole shadow of Sgr A*, the super-massive black hole at the Galaxy center, in collaboration with an international sub-mm VLBI array.

Black holes in the universe and the quest for microquasars

Main Colloquium
Dr. Felix Mirabel
ORATED
ESO, Chile

I will review the three astrophysical manifestations of black holes: AGN/quasars, microquasars, and gamma-ray burst of long duration. Then, I shall discuss the physical analogies among black holes of all mass scales, the observed coupling between accretion-disk-instabilities and relativistic ejections, and the open questions in this area of research.

The formation of massive stars

Main Colloquium
Dr. Francesco Fontani
ORATED
University of Geneva

High-mass stars (M>8Msun) play a fundamental role in the morphology and evolution of galaxies. Despite this, the processes that lead to the formation of massive stars are still poorly understood: large distances, short evolutionary timescales and clustered formation make observations of these processes challenging. In this talk, I will present some observational studies aimed at understanding the initial conditions required to form massive stars. I will also show the recent results of an extensive search for massive protostellar objects in our Galaxy, and how the new generation of instruments, specifically ALMA and Herschel, will improve this study.

When do you think it will all become clear?: Tracing the evolution of high-mass star formation regions with masers

Main Colloquium
Dr. Simon Ellingsen
ORATED
University of Tasmania, Australia

The formation of high-mass stars is an important, yet poorly understood aspect of modern astrophysics. High-mass stars play a pivotal role in Galaxy evolution through their energy input and feedback mechanisms; however critical aspects of their evolutionary development remain a mystery, as they occur while they are enshrouded in dust and gas.Interstellar masers from a number of different molecular species and transitions are common in the vicinity of young high-mass stars. They are widely used as signposts of high-mass star formation and sometimes to trace the kinematics. The combination of large-scale maser searches (e.g. Methanol Multibeam survey, HOPS) with Galactic plane surveys in the mid-infrared - submillimetre (e.g. GLIMPSE, ATLASGAL) is producing exciting new results. We are for the first time able to investigate the relationship between the physical properties of the high-mass star formation regions and the associated masers for large samples of sources. A qualitative evolutionary timeline for the major maser transitions was first put forward several years ago. I will outline recent progress towards testing and quantifying this timeline and how it fits within the broader picture of high-mass star formation.

HOPS: The H2O Southern Galactic Plane Survey

Main Colloquium
Dr. Andrew Walsh
ORATED
Department of Physics and Astronomy, Curtin University, Perth

Recent upgrades to the Mopra radiotelescope in Australia allow us to conduct large-scale surveys in many spectral lines simultaneously. I will describe an ongoing major project, HOPS, which is a survey of the southern Galactic plane at 12mm. We have so far covered nearly 60 square degrees of the Galactic plane and have detected 368 water masers, most of which are new. I will also report on detected emission in ammonia, methanol, cyanoacetylene and radio recombination lines.

Universality of galactic surface densities within dark halo cores: clues to the nature of dark matter?

Main Colloquium
Dr. Benoit Famaey
ORATED
Universite libre de Bruxelles

The universality of the mean dark matter surface density within one dark halo core radius is known to hold for galaxies spanning a luminosity range of 14 magnitudes and the whole Hubble sequence. We show that a similar relation exists for the baryonic matter, namely that the mean baryonic surface density is also universal within the halo core radius. This means that the gravitational acceleration generated by the baryonic component in galaxies is always the same at this radius. While the total baryonic-to-dark matter ratio is not universal in galaxies, our result, together with the universality of the dark matter surface density, implies that the baryonic-to-dark matter ratio is universal inside the halo core radius. We show that our finding can be interpreted as a close correlation between the enclosed surface densities of - and thus the gravitational accelerations generated by - baryonic and dark matter in galaxies. This argues in favor of a key and mysterious role played by the interactions between baryonic and dark matter in the process of galaxy formation and evolution, or even in favor of modified gravity.

The first 20 Myrs of young dense clusters

Main Colloquium
Prof. Dr. Susanne Pfalzner
ORATED
MPIfR

Most stars are not born in isolation but as part of a cluster. It will be shown that during the first 20 Myr the cluster environment influences fundamentally star and planet formation. It will be demonstrated that massive clusters do not exist in a multitude of sizes and densities, but only in two distinct types - starburst and leaky clusters.These cluster types develop along well defined tracks in the density-radius plane. This means that most stars develop in well defined specific cluster environments.

Compact Star Cluster Survey in M31 Disk

Main Colloquium
Prof. Keiichi Kodaira
ORATED
JSPS

The 8m Telescope “SUBARU” on Mauna Kea, Hawaii, has a special feature among the telescopes of this class, namely, the prime-focus camera, “Suprime-Cam”, which can cover a field  of almost  the moon-size  with an instrumental seeing of 0.2 arcsec.  During the verification period of this camera we obtained high-resolution images of the south-west part of the M31 disk (500 square-arcminutes). Using these images, a full-field search for compact non-stellar objects with apparent size less than 3arcsec (corresponding to about 10pc) was carried out, to identify about 300 candidates for compact star clusters.  They looked similar to globular star clusters but some with little irregularities, and included many blue objects of B-V<0.5. After closer inspections we selected 238 highly-probable candidates for compact star clusters (V<20.5mag) and performed an accurate surface-photometric study. The calibrated UBVRI data were applied to derive cluster parameters related to structure, age, mass, metallicity, and interstellar extinction.  The outcome of this study indicates that there are abundant star clusters which have the intermediate properties between the open clusters and the globular clusters well known in our Galaxy, bridging between the two populations.  Their spatial distribution on the M31 disk shows loose connection to 24micron hot cloud arms/rings.  Whether this new population of clusters identified in M31 disk does also exist or not in our Galaxy disk, is still an open question.  These clusters might be a powerful tool to elucidate the evolution history of galaxy disks.

Detection of Gravitational Waves with Pulsar Timing

Main Colloquium
Dr. Dick Manchester
ORATED
ATNF, CSIRO, Sydney, Australia

One of the major goals of current astrophysics is the detection and study of gravitational waves (GW). Millisecond pulsars are very precise clocks and the tiny period perturbations resulting from GW passing over the Earth can in principle be detected. Such a detection requires precision timing over several years of many pulsars spread across the celestial sphere, a so-called “Pulsar Timing Array” (PTA). PTAs are sensitive to GW with frequencies in the nHz range and hence are complementary to ground- and space-based laser-interferometer systems which are sensitive to much higher frequencies. The Parkes Pulsar Timing Array (PPTA) is a collaborative project with principal partners Swinburne University, the University of Texas (Brownsville) and the ATNF. The project commenced in 2004 and is making regular timing observations of 20 millisecond pulsars using the Parkes 64-m radio telescope at three frequencies, 680 MHz, 1400 MHz and 3100 MHz. To achieve our goals, a data span of at least five years with timing precisions of order 100 ns for a majority of the sample is required. We have attained this level of precision or better for several pulsars, but further improvements are required and considerable effort is going into improving instrumentation and data analysis procedures. International collaborations, particularly with the US NANOGrav project and the European Pulsar Timing Array project, are being established to help us reach our goals. Future prospects for PTA projects, especially in the SKA era, are described.

Finding the Gas that makes Galaxies

Special Colloquium
Prof. Art Wolfe
ORATED
University of California, San Diego

Damped Lyman-alpha absorption systems (DLAs) are a population of gas layers that dominates the neutral-gas content of the Universe in the redshift interval z=[0,5] and serves as neutral-gas reservoirs for star formation in early galaxies. In the redshift interval z=[2.5,3.5] the DLAs cover 1/3 the sky and determine the comoving mass density that decreases by a factor of 2 with decreasing redshift. However, our recent measurement of the column-density distribution function and a our search for low surface-brightness galaxies in the Hubble Ultra Deep field reveal little evidence for in situ star formation in the DLA gas. I discuss possible solutions to this paradox. Finally, I discuss results of a recent study of a DLA exhibiting 21 cm absorption.

Optical polarimetry toward the Pipe nebula: Revealing the importance of the magnetic field

Special Colloquium
Dr. Felipe de Oliveira Alves
ORATED
Institut de Ciencies de l'Espai, Barcelona

Magnetic Fields are proposed to play an important role in the formation and support of self-gravitating clouds and the formation and evolution of protostars in such clouds. We attempt to understand more precisely how the Pipe nebula is affected by the magnetic field. We use R-band linear polarimetry toward the Pipe nebula to investigate the properties of the polarization accross this dark cloud complex. Mean polarization vectors show that the magnetic field is locally perpendicular to the large filamentary structure of the Pipe nebula (the “stem”), indicating that the global collapse may have been driven along field lines. Locally, the northwestern end of the nebula (B59 region) is found to have a low degree of polarization and high dispersion in polarization angle, while at the other extreme of the cloud (the bowl) we found mean degrees of polarization as high as   15plane-of-sky field strength was estimated to vary from about 17 to 65 micro gauss across the cloud. We propose that three distinct regions exist, which may be related to different evolutionary stages of the cloud. This idea is supported by both the polarization properties across the Pipe and the estimated mass-to-flux ration that varies between approximately super-critical toward the B59 region and sub-critical inside the bowl.

Variability studies of a sample of intraday variable sources

Special Colloquium
Nicola Marchili
ORATED
MPIfR Bonn

A large number of compact flat-spectrum radio sources shows variability on time scales from hours to a few days. Several models, both source-intrinsic and source-extrinsic, have been proposed for explaining this so-called intraday variability. In case it is caused by interstellar scintillation (the most popular among the source-extrinsic interpretations) the characteristic variability time scales are expected to show an annual modulation. In 2005 a dedicated program for the systematic monitoring of a sample of intraday variable sources was started at the Urumqi radio telescope, complemented by occasional Effelsberg observations. Aim of the project is to investigate the changes in the variability characteristics of a number of prominent intraday variable sources, in order to test the predictions of the interstellar scintillation models. Strong evidence of source-extrinsic variability is found in 3 out of the 4 best monitored sources of the sample. However, there are indications that a non-negligible fraction of the variability may have a local origin, from a medium which is much closer to us than generally hypothesized - the Earth atmosphere and/or the interplanetary medium.

Dust evolution in interstellar shocks

Special Colloquium
Dr. Vincent Guillet
ORATED
Institut d'Astrophysique Spatiale, Orsay, France

Shocks in the interstellar medium have a fundamental impact on the dust that they encounter. The processing of dust by shocks can lead to changes in the dust-to-gas mass ratio through sputtering and vaporization, and also to an evolution of the dust size distribution through the competition between coagulation and shattering in grain-grain collisions. The presence of dust, and its processing, can also alter the shock structure and the gas composition. I will present the results of numerical models that simulate dust destruction and processing - and the effect of the dust on - shocks in molecular clouds, for both mono-fluid (J-type) and multi-fluid (C-type) shocks. I will emphasize the necessity of a detailed modeling of grain charging and dynamics through the shock in order to determine the impact of shocks on the dust size distribution, and its feedback on the shock structure and the evolution of the shocked gas.

The Growth of Astrophysical Understanding

Special Colloquium
Prof. Martin Harwit
ORATED
Auswärtiges wissenschaftliches Mitglied MPIfR (Cornell University)

I investigate the way that way in which our advances in astrophysical thinking take place. These advances involve a consensus of the community if they are to become genuinely accepted, and therefore are a product of how closely that community is knit. They also depend on outside influences that often determine new directions that further investigations will take, the rate at which the community may grow, and other factors. I assemble these features into a portrayal of the astrophysical community and its workings, to assess the extent to which our understanding of the Universe may significantly be a social construct rather than a representation of the Universe that flows directly, or even uniquely, from the actual structure and evolution of the Cosmos.

Galaxy Mergers, Ultraluminous Infrared Galaxies, and Quasar Activity

Main Colloquium
Dr. Sylvain Veilleux
ORATED
U. Maryland

Galaxy merging is a key driving force of galaxy evolution. In hierarchical CDM models of galaxy formation and evolution, merging leads to the formation of some elliptical galaxies, triggers major starbursts, and may account for the growth of supermassive black holes and the formation of quasars. In order to assess quantitatively the physics of the merger process and its link to elliptical galaxy formation and QSO activity, we must first understand the details of galaxy merging and its relationship to starbursts and AGNs in the local universe. Here I present the recent results from a comprehensive multiwavelength investigation of the most luminous mergers in the local universe, the ultraluminous infrared galaxies (ULIRGs) and the quasars. The issues of the occurrence, importance, and duty cycle of black hole driven nuclear activity in these objects will be covered along with their host galaxy properties and the evidence for massive gas flows in and out (past and present) of their central cores. The implications of these results on our understanding of ULIRGs and quasars in a cosmological context will also be addressed.

21-cm absorbers as probe of the physical conditions in the ISM of high-z galaxies

Special Colloquium
Dr. Neeraj Gupta
ORATED
CSIRO, Australia

In this talk I will be presenting the results from our systematic survey to search for 21-cm absorption in an unbiased sample of strong MgII systems at intermediate redshifts. This survey has allowed us to constrain the number per unit redshift of 21-cm absorbers (n21) at z<1.5. We show that n21 has fallen by a factor 4 from =0.5 to =1.3 and the decrease is most likely due to the evolution of cold neutral medium filling factor of the galaxies. Based on these results I will show that a blind search of 21-cm absorbers with upcoming SKA pathfinders will unearth a large number of 21-cm absorbers at z<1. Such unbiased surveys will be crucial for probing the physical state of the interstellar medium of galaxies at intermediate redshifts where most of the evolution in star-formation rate density takes place.

Neutron Star Dynamics

Main Colloquium
Prof. K. Kokkotas
ORATED
Universität Tuebingen

Neutron stars are promising gravitational waves sources. We will review the prospects of detecting gravitational waves from newly born and older neutron stars, we will present some recent results concerning the rotational instabilities and finally we will show our recent analysis of the dynamics of magnetars.

A close relation between AGN gamma-ray emission as measured by Fermi and properties of parsec-scale radio jets

Main Colloquium
Dr. Yuri Kovalev
ORATED
NRAO Green Bank & Lebedev Physical Institute, Moscow

A list of 205 bright gamma-ray objects was recently reported using data from the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope. Comparison of the LAT positions with accurate radio positions of a VLBI-selected sample of extragalactic jets finds a total of 112 radio – gamma-ray counterparts including six new associations. Further comparison of VLBA observations of AGN parsec-scale radio emission with their associated gamma-ray properties shows that they are closely related. Fermi-detected radio jets are found to have faster flow velocities than the non gamma-ray jets, they also appear brighter and more compact. This suggests that gamma-ray bright AGN have preferentially higher Doppler boosting factors than other blazar jets. The correlations found between the temporal radio and gamma-ray variability suggest that the prominent flares in both bands are produced in the parsec-scale cores, typically within an apparent time separation of up to a few months. These results indicate that relativistic beaming of the jet emission is important in both the radio and gamma-ray bands.

Massive Stars: Evolution and Nucleosynthesis

Special Colloquium
Dr. Raphael Hirschi
ORATED
Keele University, UK

TBA

Early stages of massive star formation: a challenge for observations

Main Colloquium
Silvia Leurini
ORATED
MPIfR Bonn

Despite their importance, our current understanding of the formation of high mass stars remains very schematic. In this talk, I will briefly review our knowledge of the process of massive star formation. I will discuss a few observational tests that may help discriminate between different models of massive star formation with emphasis to the importance of studies of very early evolutionary phases. As a case study, I will present observations of the southern region G351.78-0.54, which we intensively studied at mm and IR wavelengths in the last years. The region shows signs of on-going massive star formation towards a bright IRAS source, and evidence of earlier evolutionary phases of star formation in several clumps along a dust filament. I will also discuss interferometric observations towards the most evolved source in the filament, which nicely outline the complexity of massive star forming regions and the limitation of current facilities to properly investigate them.

Current Activities at the NRAO

Special Colloquium
Prof. Fred Lo
ORATED
NRAO

I will give a status report on the science, construction and operations activities at the NRAO, including an update on the Megamaser Cosmology Project.

Cosmic-Ray driven dynamo in galactic disks

Main Colloquium
Dr. Michal Hanasz
ORATED
Nicolaus Copernicus University, Torun, Poland

I am going to present recent developments of local and global, galactic-scale numerical models, of the Cosmic-Ray driven dynamo, which was originally proposed by Parker (1992). We conduct a series of direct CR-MHD numerical simulations of the dynamics of interstellar medium, composed of gas, magnetic-field, and cosmic-ray components. We take into account cosmic rays, accelerated in randomly distributed supernova remnants, and assume that supernovae deposit small-scale, randomly oriented, dipolar magnetic-fields into the ISM. We find that, the magnetization of galactic disks by exploding magnetized stars forms a favourable initial condition for the galactic dynamo process. The amplification timescale of the large-scale magnetic field, resulting from the CR-driven dynamo, is comparable to the galactic rotation period. The process converts efficiently small-scale magnetic fields of SN-remnants into the galactic-scale magnetic fields. The resulting magnetic-field structure resembles the observed X-shaped magnetic fields in edge-on galaxies.

Radio Properties of Brightest Cluster Members (BCMs)

Special Colloquium
Prof. Heinz Andernach
ORATED
University of Guanajuato

From the Abell catalog of rich clusters of galaxies we selected a subsample of 1207 clusters likely to have a dominant galaxy, namely those with Bautz-Morgan type I and I-II, with Rood-Sastry type “cD”, and those with textual notes in the Abell catalog hinting at the presence of galaxies with “coronae”. Our visual inspection of this cluster sample on DSS images (Coziol et al. 2009) yielded 1423 candidates for brightest cluster members (BCMs) towards 1169 different Abell clusters. We used the source catalogs and images of existing radio surveys (VLSS, WENSS, SUMSS, NVSS, FIRST, etc.) as well as the literature to collect radio fluxes and radio morphologies for these BCMs. Of the 1424 BCMs 590 (41at more than one frequency, allowing to estimate their radio spectral index. I present preliminary results of this work in progress, showing the large variety of radio morphologies including several FR II type sources rarely found in rich clusters, as well as a few examples of very radio-quiet BCMs. The intended statistical analysis of the data include a search for relations between various radio and optical characteristics of the BCM, like radio luminosity, radio morphology and spectral index, optical morphology and ellipticity, peculiar velocity within their host cluster, as well as the radio-optical alignment angle.

Radio interferometry of maser sources in high-mass star forming regions

Special Colloquium
Birgit Ritter
ORATED
MPIfR, Bonn

Still, little is known about the real structure of our Milky Way. It is known to possess spiral structure, but the number of spiral arms is still under debate. The main problem is that distance determinations are difficult since we are located within the plane of the Galaxy. The most reliable way to determine a distance is the trigonometric parallax, which is unbiased by any intrinsic source properties. VLBI techniques enable to measure parallaxes up to distances of several kpc in each direction. Interstellar maser sources in high-mass star forming regions (HMSFRs) have proven to be useful targets as they are compact and bright objects. Currently large projects are undertaken in order to map the Milky Way by VLBI parallax measurements of such sources. I will present VLA observations of 6.7 GHz methanol and 22 GHz water maser sources in HMSFRs that were conducted in order to define accurate phase center positions for follow-up VLBI parallax measurements. Furthermore I will describe the VLBA observations of 12.2 GHz methanol masers in the high-mass star forming region G25.71+0.04 and discuss its location and proper motion within our Galaxy.

Studying the magnetised ISM with radio polarimetry

Special Colloquium
Dr. Andre Waelkens
ORATED
MPE Graching

The structure and statistics of magnetic fields in the ISM are still unknown, despite their importance for the regulation of star formation, cosmic ray propagation, and CMB forground synchrotron emission. Advances in our knowledge have to come from the interpretation of multi-frequency data. To this end, I will present a number of probes for properties of the magnetised ISM on all scales. To study turbulence in the ISM, we develop an estimator for the magnetic tension-force spectrum. It is based on polarised synchrotron emission data in the Faraday-rotation-free frequency regime. The tension force is the dynamically most important magnetic force in subsonic magnetic turbulence. The method is applied to mock observations based on MHD simulations as a prelude to an application to real observations. To investigate the global Galactic ISM properties we developed the hammurabi code, capable of producing mock synchrotron, RM, DM and UHECR deflection observations. Therefore it permits to confront models of the Galactic magnetised plasma with a broad range of real observations. I will report on a number of works based on this code, and give an outlook on future projects I believe hammurabi is suited for.

Quantifying Dark Energy with Cosmic Shear

Main Colloquium
Dr. Sarah Bridle
ORATED
University Colloge London

I will summarise the evidence for dark energy and the basics of cosmic shear. My talk will then focus on how to obtain the maximum constraining power from the upcoming experiments to measure dark energy using cosmic shear. I will introduce the GRavitational lEnsing Accuracy Testing 2008 (GREAT08) Challenge, which is an image analysis competition to improve shear measurements. I will also describe the potentially confusing signal from intrinsic galaxy alignments and how it can be addressed.

The Planet-Disc connection

Special Colloquium
Prof. Cathie Clarke
ORATED
Cambridge

TBA

The DiFX software correlator in Bonn

Special Colloquium
John Morgan
ORATED
Bologna

Software correlators allow correlation to be done on standard computer clusters rather than custom hardware. Progress has been rapid in recent years and many VLBI “hardware correlators” are being switched off to make way for more flexible software correlators. DiFX [1] is one such software correlator whose use is being investigated by several institutes including MPIfR. In this talk I will give a brief introduction of software correlators, followed by an overview of the work being carried out here with particular focus on using DiFX for widefield VLBI and adapting DiFX for geodetic use. I will conclude by discussing new possibilities that software correlation offers astronomers. [1] Deller, Tingay, Bailes & West 2006, PASP, 119, 318

Principal Component Analysis of Molecular Line Observations of Massive Star-Forming Clumps

Special Colloquium
Adam Fallon
ORATED
MPIfR, Bonn

Principal component analysis (PCA) is a tool from multivariate statistics used to find the directions which account for the most variance in a data set. Such tools are of interest in astronomy due to the availability of increasingly large data sets. In this work PCA was applied to three main data types derived from molecular spectra of massive star-forming regions: integrated intensities, spatial maps of integrated intensities, and molecular line velocities, with the goal of assessing the usefulness of PCA in finding a simplified description of the data, and to learn if any physical insights were possible from this process. In the integrated intensity sample it was found that PCA does separate the sources into groups with distinct characteristics, and therefore has potential as a source classification aid. The results from the map and molecular line velocity samples were less notable, however some technical observations regarding the influence of noise and artifacts were made.

Science with the Austrailan Square Kilometre Array Pathfinder

Main Colloquium
Dr. Simon Johnston
ORATED
ATNF, CSIRO, Sydney, Australia

The future of cm and m-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries that will be 50 times more sensitive than any existing radio facility. Most of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from a few hundred MHz to a few GHz. The Australian SKA Pathfinder is a technology demonstrator aimed in the mid-frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phased-array feed systems on parabolic reflectors. The large field-of-view makes ASKAP an unprecedented synoptic telescope that will make substantial advances in SKA key science. ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of two sites selected by the international community as a potential location for the SKA. In this talk, I will outline the ASKAP project and summarise its headline science goals as defined by the community at large.

An In-depth Study of the Interstellar Medium in the Barred Spiral Galaxy NGC3627

Special Colloquium
Christof Buchbender
ORATED
MPIfR, Bonn

I will present a study of the cold, dense, star forming ISM in the barred spiral galaxy NGC3627, with the final goal to obtain a spatially resolved Schmidt-Kennicutt law, which is a power law relation between the star formation rate (SFR) and the gas mass surface density. NGC3627 is located in the nearby Leo Triplet with a distance of about 9 Mpc. It is strongly interacting with its nearest neighbor NGC3628 and as such it is representative for a large number of galaxies where gravitational interaction has triggered the formation of a bar and the associated SF activity along the bar and in the nuclear region. To investigate the molecular gas in NGC3627 measurements of the CO(1-0) line as well as 1.2 dust continuum emission were used. With these two tracers of molecular mass at hand it is possible to study local variations of the X-factor, which relates CO(1-0) intensity to H_2 column density, across the disk of the galaxy. These observations are complemented by HI, Halpha, and 24,70 and 160 micron Spitzer observations, allowing to determine dust temperatures, SFRs, and atomic gas masses across the disk of NGC3627. This comprehensive wavelength coverage provides a good view into the structure of the different components of the cold ISM in this galaxy.

Apertif, upgrading the WSRT and pathfinder for SKA

Main Colloquium
Dr. Thomas A. Oosterloo
ORATED
ASTRON (Netherlands)

Apertif is a programme aimed to upgrade all dishes of the Westerbork Synthesis Radio Telescope (WSRT) with focal plane arrays. This will lead to an improvement of the field of view with a factor 25 and the survey speed of the WSRT will increase with a similar factor. This will turn the WSRT into a powerful survey instrument. The technology is also relevant for SKA. I will discuss the technical aspects of Apertif and show first results obtained with a prototype focal plane array currently mounted in one of the WSRT dishes. I will also discuss the science case for Apertif that is very diverse, including the search for the smallest galaxies, the evolution of the gas content of galaxies with redshift, cosmic magnetism as well as pulsars and transients.

MIDI/VLTI-Infrared Interferometry of the young, massive star Allen's Source

Special Colloquium
Rebekka Grellmann
ORATED
MPIfR, Bonn

Allen’s Source is a young star with a mass of 9.5 solar masses, therefore belonging to the intermediate to high-mass stars. Our knowledge about the formation of high-mass stars is still very limited. With a distance of 760 pc Allen’s Source provides the unique possibility to investigate its circumstellar environment on scales of few AU. With MIDI, the mid-infrared instrument of ESO’s Very Large Telescope Interferometer (VLTI), spectral dispersed Michelson interferograms of Allen’s Source were taken at wavelengths between 8 and 13 micron. For the interpretation of the data the radiative transfer code DUSTY was employed to extract physical parameters of a possible circumstellar envelope. Furthermore, a temperature-gradient model for a possible disk around the object was tested.

On the ortho-to-para ratio of H2 in dark clouds: from theory to observation

Special Colloquium
Dr. Nicolas Troscompt
ORATED
LAOG, Grenoble

The ortho-to-para ratio (OPR) of molecular hydrogen is a fundamental parameter to understand the physics and chemistry of the interstellar medium (ISM). In dark and cold clouds, however, H2 is not directly observable and the OPR of H2 in these sources has remained so far elusive. In this talk, I will show that the absorption line of H2CO at 6cm, with resolved hyperfine components, can be employed to estimate the OPR of H2 in dark clouds. Indeed the excitation temperature of this line is strongly sensitive to the collisional perturber. I will present 1) new calculations of rate coefficients for the rotational excitation of H2CO by both para- and ortho-H2 and 2) new GBT observations and radiative transfer modelling of H2CO toward dark clouds.

Galaxy clusters, jets, and magnetic fields

Special Colloquium
Dr. Martin Krause
ORATED
MPE Garching

The magnetic field in present day clusters is dominated by a turbulent component at sub-equipartition with respect to the thermal energy density, consistent with (sub-)sonic turbulence. Not much is known about higher redshifts. I will discuss a recent theoretical approach that incorporates results from magnetohydrodynamic turbulence calculations into a cosmological simulation, and present model predictions for magnetic field measurements via Faraday rotation studies with the upcoming LOFAR telescope and the Square Kilometre Array. An important ingredient to the physics of galaxy clusters are radio jets. They are important for the heat balance and possibly metal transport within the clusters, they interact with cold gas especially at high redshift, which might be important for galaxy formation, they tell about the central engine and may enhance the magnetic field in the intra-cluster medium. I will present magnetohydrodynamics simulations of the interaction of jets with their environment, with realistic magnetic field configurations in the jet and also in the ambient cluster gas.

Phenomenological approach to the multi-wavelength study of blazars

Special Colloquium
Dr. Andrea Tramacere
ORATED
SLAC Stanford, ASI-INAF Rome

I will present a phenomenological approach to the multi-wavelength study of blazar emission. In the first part I will demonstrate how to use UV/X-ray data to search for signatures of stochastic acceleration processes in BL Lac (HBL) objects. It will be discussed how these features can be linked to predict the GeV/TeV emission, and how the intrinsic spectral curvature is relevant to understand the Extragalactic Background Light (EBL) issue. In the second part I will discuss the multi-wavelength emission from flat-spectrum radio quasars in the framework of the external Compton scenario. I will show how changes in different physical parameters can account for different patterns in the spectral evolution. Finally, I will present recent (2008/2009) results for PKS 1510-089, showing new radio (Effelsberg, F-Gamma project), opt/UV, X-ray and gamma-ray (Fermi-LAT) observations.

Studying the Nature of Dark Energy with Galaxy Clusters

Special Colloquium
Dr. Thomas Reiprich
ORATED
AIfA

After an introduction how dark energy influences the growth of galaxy clusters – the most massive collapsed structures in the Universe, I’ll present the latest results from our X-ray follow-up of a complete local sample of the 64 X-ray brightest clusters in the sky as well as a nearby sample of 26 galaxy groups. Multiwavelength (radio, sub-/mm, optical) properties of the samples as well as the effect of feedback from central supermassive black holes on cluster atmospheres will also be mentioned. Furthermore, I’ll report on the status of our optical weak gravitational lensing follow-up of a complete high-z sample of 40 clusters. The combination of the samples will be used for robust constraints on the nature of dark energy through the evolution of the cluster mass function and merger frequency. Moreover, the usefulness of these high quality observations for future large X-ray surveys, like eROSITA, will be discussed.

How much light was produced since the Universe was born? Finally, a way to measure it.

Special Colloquium
Dr. Markos Georganopoulos
ORATED
University of Maryland, Baltimore County, USA

The extragalactic background light (EBL) that permeates the Universe in the optical-IR is essentially an integral of the light produced from the time the first stars were formed in our Universe until now. As such, it is a quantity that is very closely connected to the galaxy/ large scale structure formation in our Universe. Unfortunately, measuring the EBL has been proven very difficult, for very simple reasons that I will discuss in the first part of my talk. Luckily, we found an unexpected, parameter-free way to break the deadlock of measuring the EBL with Fermi, NASA’s new Gamma-ray satellite. This will be the second part of my talk. Fermi measurements are underway and the determination will take about two years.

The Effect of dense clouds on the SED of disc like galaxies

Special Colloquium
Dr. Joerg Fischera
ORATED
Mt Stromlo Observatory, Australia

The effects of the in-homogeneous density structure of the dusty interstellar medium (ISM) on the spectral energy distribution (SED) of disc-like galaxies are analyzed in the approximation of an isothermal self-gravitating infinite slab with typical scale heights of the ISM and the stars. The stellar distribution is divided into a ‘young’ stellar component of hot stars in the dusty disc and an ‘old’ stellar component of colder stars with larger scale height. The ISM is described by a two-phase model of dense self-gravitating clouds which are embedded in an otherwise homogeneous medium. The radiative transfer problem is for given central pressure of the ISM, chosen to be in agreement with the value in the Milky-Way, determined by the amount of mass in dense clouds relative to the mass in the inter-cloud medium. In its solution problems of multiple scattering, non-isotropy of the scattered emission and re-heating of dust grains are considered. The thermal dust emission is derived using a physical dust model of stochastically heated grains.

Molecular gas content and star formation modes in high redshift massive galaxies

Main Colloquium
Dr. Emanuele Daddi
ORATED
CEA, Saclay, France

I will present results from our ongoing surveys probing the molecular gas content of distant galaxies with the IRAM Plateau de Bure Interferometer and the VLA. We recently discovered that ordinary near-IR selected galaxies at z>1 are very luminous CO emitters and can be routinely observed and studied already with existing facilities. We also unveiled a substantial population of z>4 bright submm galaxies in the GOODS-N field. Star formation modes in the distant Universe can be understood in terms of the spiral/ULIRG duality that is well characterized locally.

Westerbork observations of the Galaxy at 150 MHz: foregrounds for observations of the cosmological 21 cm line

Special Colloquium
Dr. Gianni Bernardi
ORATED
Kapteyn Astronomical Institute, University of Groningen

The detection of the cosmological 21 cm line is a very promising tool to investigate the reionization epoch, when the first galaxies were born. However its detection is plagued by strong Galactic and extragalactic foreground emission. We present results from total intensity and polarization observations of selected areas in the Galaxy, aimed at characterizing the foreground properties and we discuss the implications for the measurement of the cosmological signal.

The APEX southern sky survey of high mass star forming regions

Special Colloquium
Carolin Dedes
ORATED
MPIfR Bonn

In my dissertation, I characterized the physical and chemical properties of a sample of 47 high mass star forming regions by observing it with the new Atacama Pathfinder EXperiment (APEX) 12m telescope, and in parts with the Australia Telescope Compact Array (ATCA). These observations were done between 86 and 810 GHz in the mm and sub-mm regime, where most of the high mass star forming activity can be observed. This is the first study which combines a sub-mm dust continuum and molecular line survey on a large number of sources, and it resulted in a database of southern hemisphere sources well suited for follow-up studies with the high resolution capabilities of the ALMA interferometer. In my talk, I will give an overview of my dissertation work and discuss in more detail the density profile fitting of the dust continuum, the derivation of infall properties for the sample and the chemical analysis of eight hot cores found in the molecular line data.

What we do not know about galactic magnetic fields and why

Special Colloquium
Dr. Anvar Shukurov
ORATED
University of Newcastle, UK

The focus of this review of galactic magnetic fields is on unresolved problems. I will make an attempt to isolate the most physically important problems (the choice, however, remains subjective), briefly present earlier attempts to solve them, discuss why those attempts have not been convincing, and suggest what can we gain from solving these problems. The problems involved range from the dynamics of the multi-phase interstellar medium, to the disc-halo connections in spiral galaxies, and their connection to galactic magnetic fields.

The little bang in the laboratory: creating the quark-gluon plasma

Main Colloquium
Prof. Johanna Stachel
ORATED
Physikalisches Institut der Universität Heidelberg

The theory of strong interaction, Quantum Chromo Dynamics (QCD) predicts that at high temperature and density a new state of matter is created in which the confinement of quarks and gluons is lifted. This state which must have existed in the early universe until about 10 microseconds after the big bang is called the Quark-Gluon Plasma (QGP). Since about 20 years experiments are conducted in the laboratory to recreate this state of matter. The understanding is that this is done by colliding heavy atomic nuclei at as high energies as possible. Initially this was done by bombarding stationary targets with beams at the BNL AGS and the CERN SPS and in 2000 the evidence mounted that indeed a new state of matter was created. Since then a dedicated colliding beam accelerator, RHIC at BNL has come into operation. The results at RHIC give very strong arguments in favor of the QGP creation but also indicate that the properties of this state may be quite different from what was initially expected. This talk will review the experimetal results and give an outlook to the future experimetal program in this field starting at the LHC in 2009.

Beaming and de-beaming of relativistic jets: translating observed quantities and appearances into intrinsic ones

Special Colloquium
Dr. Sebastian Jester
ORATED
Fermilab

Relativistic beaming and effects like apparent superluminal motion are familiar concepts by now, but still hold surprises for our non-relativistic intuition. In particular, angle aberration has entirely unfamilar effects on how relativistic objects appear in pictures. I show that there is a spatial corollary to apparent superluminal motion, which makes relativistic objects appear longer than they are (in our frame). As a consequence of this ”retardation magnification”, we cannot see (or photograph) all parts of a relativistic jet simultaneously. Going from visualising to quantitative work, there are contradictory de-beaming formulae for minimum-energy magnetic fields. The contradiction is resolved by making a clear distinction between varying beaming parameters for fixed *source* and for fixed *projection*; the latter corresponds to interpreting astronomical observations.

Radio Wave Propagation as a Probe of the Cosmos

Special Colloquium
Dr. Bryan Gaensler
ORATED
Sydney University

The Universe is largely transparent to radio waves, but this does not mean that these signals are unaffected by their passage. Substantial information about otherwise unobservable phenomena is imprinted on radio waves as they propagate, in forms such as dispersive delays, Faraday rotation and interstellar scintillation. I will discuss two studies of these propagation effects, representative of the incredible diversity of physical processes which can be revealed by such measurements. First, I will present a new analysis of pulsar dispersion measures, which demonstrates that the ionized gas layer of the Milky Way is twice as thick as previously thought. I will then show how spectropolarimetry of active galactic nuclei can probe deep within the central engine, and will discuss plans to thus carry out an all-sky census of merging supermassive black holes.

Funding by COST (European Cooperation in Science and Technology)

Informal Colloquium
Dr. Piotr Swiatek
ORATED
NCP, FZ Juelich

COST is an intergovernmental framework for European Cooperation in Science and Technology, allowing the coordination of nationally-funded research on a European level. Financial support is granted for joint activities such as conferences, short-term scientific exchanges and publications. COST therefore can be used as a strategic instrument for preparing new research projects on a multinational level. The talk is aiming at presenting the COST-Programme and at the same time giving practical advice and support on how to apply for a COST Action. The speaker Dr. Piotr Swiatek has long term experience with and insider knowledge on the COST programme, as he has been working for four years (2004-2008) as senior science officer in the ”Materials, Physical and Nanosciences” domain at the COST Office in Brussels.

Funding Opportunities for Postdocs: The Marie Curie Programme of the European Commission

Informal Colloquium
Viola Tegethoff
ORATED
Scientific Officer, MPG Office in Brussels

Are you about to finish your doctorate and are your planning “the time after”? Or are you already a postdoc seeking for a new challenge in your early career as scientist? The Marie Curie Programme of the European Commission is an interesting alternative to personal funding schemes of e.g. the German Research Foundation (DFG), as it enables you to move with your own salary and some extrafunds to a research institute / university in Europe or abroad (e.g. USA, Australia,...). The programme does not have age limits, so it can be an interesting option both for young postdocs and experienced postdocs. The European Commission will publish the next Call for Proposals on March 18, 2009 with a deadline on August 18, 2009. The presentation will inform on the programme itself and especially on how to prepare a (successful) proposal within the Marie Curie Programme.

The Dark Energy Survey

Special Colloquium
Dr. Brenna Flaugher
ORATED
Fermi National Accelerator Laboratory

The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding the expansion rate of the universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type IA supernovae. To perform the survey, the DES Collaboration is building the Dark Energy Camera (DECam), a 3 square degree, 520 Megapixel CCD camera which will be mounted at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory. The survey will cover 5000 square-degrees of the southern galactic cap with 5 filters (g, r, i, z, Y). DECam will be comprised of 74 250 micron thick fully depleted CCDs: 62 2k x 4k CCDs for imaging and 12 2k x 2k CCDs for guiding and focus. DECam will be used to perform the Dark Energy Survey with 30of the telescope time over a 5 year period. During the remainder of the time, DECam will be available as a community instrument. I will present an overview of the DES science plans and the status of the instrument construction.

Jets in X-ray binary systems

Main Colloquium
Dr. Valeriu Tudose
ORATED
Sterrenkundig Instituut Anton Pannekoek, University of Amsterdam

An X-ray binary (XRB) is a system comprising a compact object (neutron star or stellar mass black hole) accreting matter from a companion star via an accretion disk. In some particular states of this complex system, matter is ejected from a region close to the compact object in the form of two opposite, often relativistic jets. Although semi-empirical qualitative models have recorded notable successes, at the moment it is not entirely clear what is the exact connection between the accretion process and the launching of the jets. This is a fundamental question, going beyond the limits of the galactic studies, since evidence is mounting that the accretion/ejection process in active galactic nuclei (AGNs) presents to some degree similar features to XRBs. Equally notable is that the timescales of the phenomena associated with the XRBs also allow to study their surrounding environment via the interaction of the jets with the interstellar medium. From the observational point of view the best approach to study the XRBs is with quasi-simultaneous multi-wavelength observations, however logistically speaking such campaigns are not easy to set up. In the context outlined above, I will exemplify with results obtained for some particular systems, among which Cir X-1, Cyg X-3, Aql X-1, SS 433. The focus is primarily on the radio observations of these objects (with e-EVN, ATCA, VLA), but in some cases X-ray observations (RXTE, Chandra) and optical (SMARTS) are also discussed.

Diffuse neutral ISM: temperature and turbulence

Special Colloquium
Dr. Nirupam Roy
ORATED
MPIfR

The thermal equilibrium model shows that different phases of the diffuse neutral ISM can be in pressure equilibrium in one of the two stable ranges of kinetic temperature, viz.   40 - 200 K for the CNM and   5000 - 8000 K for the WNM. But, recent observations indicate that a significant fraction of the neutral ISM is in the thermally unstable region. The classical method of determining the WNM temperature, however, provides an upper limit to the temperature because turbulence contribute to the observed line width. In this talk, I will discuss about different issues with the classical method of estimating the WNM temperature and about a possible way to quantify the contribution of turbulence to the line width. This will allow us to correctly determine the amount of neutral gas in the unstable state and to critically re-examine the thermal equilibrium model of the ISM.

The Future of Astronomy from Antarctica

Special Colloquium
Prof. John Storey
ORATED
UNSW Sydney

As our understanding of the unique conditions on the Antarctic plateau continues to grow, it is becoming clearer which areas of astronomy are likley to benefit the most from new Antarctic observatories. In the optical/IR, the combination of clear skies and very low levels of optical turbulence create unprecedented opportunities for high-resolution, wide-field imaging and spectrospcopy. In addition, time-series observations can benefit from the long, uninterrupted periods of darkness. At terahertz frequencies and into the sub-mm, the stability of the sky and low precipitable water vapour should allow routine observations at wavelengths that are difficult or even unobservable at any other location on the earth’s surface. Concordia Station at Dome C has now been operating for four years, and just yesterday the offical opening took place of the new Chinese station, Kunlun, at Dome A. This talk will review the current state of knowledge of site conditions, and explore the opportunities presented by Dome C and Dome A.

Current Status of the Delta Quadrant Survey

Special Colloquium
Dr. Maria Cunningham
ORATED
University of New South Wales, Sydney, Australia

The G333 Survey is a multi-molecular line survey of the G333.6-0.2 giant molecular cloud complex, motivated by the idea of gaining a comprehensive picture of massive star formation throughout an entire GMC. We have used the new broadband capabilities of the Mopra telescope to map the distribution of around 20 different molecules in this approximately 1 degree square region of the southern Galactic plane. In the analysis of this complex data set, we have used two analysis techniques suitable for application to large data sets, both of which have yielded interesting results: Spatial Power spectrum and Principal Component analysis (PCA). We have investigated the spatial power spectrum of a variety of molecules that trace different critical densities. Surprisingly, all molecules show a similar power law slope, suggesting a picture where turbulence is injected at large scales (at least tens of parsecs), and passes through to smaller scales, and higher densities, without significant dissipation. The large scale of energy injection is supported by other analyses, which hint that the initial wave of star formation in the complex may have been triggered by a merger between two large-scale Galactic flows. However, the PCA analysis has shown that, despite the apparently uniform distribution of turbulent energy through the different molecular regions, different molecules are well differentiated at smaller scales. The PCA and has yielded some significant chemical correlations and anti-correlations, which we compare with model predictions.

The Stromlo Missing Satellites Survey

Main Colloquium
Dr. Helmut Jerjen
ORATED
Research School of Astronomy and Astrophysics, Mt. Stromlo Observatory, Australia

The SMS program is a critical endeavor to investigate whether the predictions of standard cold dark matter cosmology are consistent with the observed matter distribution in the Milky Way halo. It is the deepest, most extended search for optically elusive dwarf satellite galaxies and tidal streams to date, covering the entire 20,000 square degrees of the Southern hemisphere. The 150 TB of CCD images in six photometric bands, 0.5-1.0 mag fainter than the Sloan Digital Sky Survey, will be produced by the SkyMapper telescope of the Australian National University over the next five years. The primary objective of our program is to study the baryonic and dark matter components of the newly detected stellar overdensities in unprecedented details providing the best physical picture of the phenomenon ”dwarf satellites” and stringent empirical constraints to test CDM theory.

The non-ballistic model for the superluminal motion in AGNs

Special Colloquium
Prof. B. Gong
ORATED
Huazhong University, Wuhan, China

The long-term multi-epoch observations of quasars, active galaxies, tracing the structure further along the jets and following the motion of individual features for longer time, rise questions that are difficult to understand by the standard scenario of superluminal motion. I.e., the ejecta are aligned with the local jet direction, instead of the core; and within individual jets apparently inward-moving features are observed. Here we show that these unexpected phenomena actually indicate the existence of non-ballistic jet motion, in which a continuous jet produces a discrete hot spot. And the precession of such a hot spot leads to the superluminal motion in the plane of the sky. The new model provides a simple and unified interpretation to the superluminal motion of two AGN sources 0735+178 and 0119+041. And it is expected to apply to more AGNs.

An Engineer's Astronomers' Guide to the Australian SKA Pathfinder

Main Colloquium
Dr. David DeBoer
ORATED
Seti Institute, USA

Great surveys at all wavelengths are charting our place in the cosmos. The Australian SKA Pathfinder (ASKAP) will be one of the fastest and best survey telescopes in the important 700-1800 MHz frequency range and will trial technology for the SKA. ASKAP will comprise 36 12-meter antennas, each with a phased array feed yielding a field-of-view of about 30 square degrees. It is being built in the remote Western Australia Outback at Australia’s candidate SKA site. This area is being developed as the Murchison Radio Observatory and is arguably the world’s best site for cm-wave astronomy. This talk will provide an overview and status of ASKAP.

Fragmentation of massive star-forming clusters

Special Colloquium
Dr. Javier A. Rodon
ORATED
MPIA Heidelberg

TBA

What can we learn from synthetic emission maps for the jet of M87?

Special Colloquium
Dr. Jose Gracia
ORATED
Dublin Institute for Advanced Studies (DIAS)

We present a self-consistent MHD model for the jet of M87. The model consist of two distinct zones: an inner relativistic outflow and an outer cold disk-wind. While the former does not self-collimate efficiently due to its high effective inertia, the latter fulfils all the conditions for efficient collimation by the magneto-centrifugal mechanism. The relativistic flow is thus magnetically confined into a well collimated beam for a wide range of parameters. Comparison of observed radiomaps and synthetic synchrotron emission calculated from the MHD models are used to select a best fitting model based on constraints on the opening angle and limb-brightening of the jet. We argue, that the limb-brightening is not an apparent effect, i.e. Doppler de-boosting into the line-of-sight, but due to an intrinsic accumulation of magnetic flux at the outer edge of the jet. Additionally, our model reproduces some of the properties of the optically bright knot HST-1. Finally, we line out how linear polarisation measurements in addition to total intensity can further constrain the topology of the magnetic field in the jet beam.

Rotational line emission from water in protoplanetary disks

Special Colloquium
Dr. Dieter Poelman
ORATED
University of St. Andrews

One of the most fundamental questions to date in modern astrophysics is how stars and planets form. Protoplanetary disk evolution and planet formation are closely entangled. Therefore, to understand their formation mechanisms, one first needs to develop a comprehensive picture of the physical and chemical conditions in protoplanetary disks. In this talk, I will present recent work in combining a thermal-chemical model of a typical T Tauri star disk with a molecular line radiative transfer program to investigate the diagnostic potential of the far-infrared lines of water. I discuss the observability of pure rotational water lines with the Herschel Space Observatory.

Fast Radiation Transport for Hydrodynamical Simulations of Massive Star Formation

Special Colloquium
Rolf Kuiper
ORATED
MPIA Heidelberg

We investigate the radiation pressure feedback depending on the morphology of the stellar environment in one-, two-, and three-dimensional monolithic collapse calculations of massive pre-stellar cores. In contrast to previous research, we (1) consider frequency dependent radiation feedback,(2) use a newly developed hybrid radiation transport scheme, including ray-tracing as well as flux limited diffusion, (3) resolve the dust sublimation front in the vicinity of the forming star down to 1.27 AU,(4) compute the whole accretion phase of the new born star up to several 10^{5} yr, and (5) perform a comprehensive survey of the parameter space (more than 40 simulations by now). Our simulations in axial symmetry demonstrate in detail that not resolving the dust sublimation front artificially terminates the disk accretion epoch. Our most fundamental result is that the formation of massive accretion disks enforces a strong anisotropy of the thermal radiation field, enabling steady accretion through the shielded disk region. In 3D the self-gravity of the disk drives a sufficiently high accretion rate to overcome the residual radiation pressure. Simultaneously, a stable large-scale bipolar outflow is launched due to radiative forces. Summing up, the various simulation series draw a consistent picture of the formation of the most massive stars via classical disk accretion. For an initial pre-stellar core mass of 60, 120, 240, and 480 Msol these mechanisms allow the central star to grow up to 27, 57, 93, and more than 137 M_odot respectively.