I will report new simultaneous near-infrared/sub-millimeter/X-ray
observations of the SgrA* counterpart associated with the massive 3-4
million solar masses black hole at the Galactic Center. The observations
have been carried out using the NACO adaptive optics (AO) instrument at
the European Southern Observatory’s Very Large Telescope and the ACIS-I
instrument aboard the Chandra X-ray Observatory as well as the
Submillimeter Array on Mauna Kea, Hawaii, and the Very Large Array in
New Mexico. In addition preliminary results from a recent VLA observing
run on NIR polarimetry of SgrA* flare emission is presented.
Black holes and cosmological evolution
Special Colloquium
Prof. Laszlo Gergely
ORATED
Departments of Theoretical and Experimental Physics, University of Szeged, Hungary
Modern cosmological precision experiments, in particular distant
supernovae surveys, suggest that a significant part of our universe is
composed of a mysterious dark energy. An equivalent interpretation would
be to modify gravitational dynamics in order to comply with
observations. In this talk I discuss recent scenarios in which our
observable universe is regarded as a (mem)brane in a higher-dimensional
spacetime. Consequently, the cosmological evolution can be different
from the standard one both at high energies and at low densities.
Finally, I review what is known on black holes and gravitational
collapse in such theories.
Recent advances in VLBI astrometry
Special Colloquium
Dr. Mark Reid
ORATED
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, U.S.A.
I will describe measurements with the VLBA of the position of Sgr A*
with respect to two extragalactic radio sources over a period of eight
years. The apparent proper motion of SgrA^* relative to J1745-283 is
almost entirely along the plane of the Galaxy. The effects of the orbit
of the Sun around the Galactic center can account for this motion, and
the residual proper motion of SgrA^* is exceedingly small. I will show
how an upper limit on the motion of SgrA^* implies a lower limit to its
mass. This mass limit, coupled with upper limits to the apparent size of
SgrA^*, provides overwhelming evidence that SgrA^* is a super- massive
black hole. Our observations provide the first direct evidence that a
compact radio source at the center of a galaxy contains sim10^6 Modot.
Also, the existence of ``intermediate mass" black holes near the
Galactic Center are strongly constrained by our observations.
Dust and Molecular Gas in High-Redshift Galaxies and Quasars
Main Colloquium
Dr. Pierre Cox
ORATED
IRAM, Grenoble
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 38 sources spanning a range
in redshift from 1
Cosmology on a Supercomputer: Following the joint formation and
evolution of galaxies and quasars
Main Colloquium
Dr. Volker Springel
ORATED
MPA, Garching
Cosmological simulations have become a primary tool for studying the
non-linear regime of structure formation starting from the initial
conditions of the LCDM concordence cosmology. I present results from the
”Millennium Simulation”, the largest cosmological N-body calculation
performed to date. We track structure growth with a spatial resolution
of 5 kpc/h within a typical region of the Universe more than 2 billion
light-years across. Approximately 20 million dark matter halos form in
this region. I discuss techniques for following post hoc the formation
of visible galaxies within them, using simple physical models for the
cooling and condensation of gas, for its transformation into stars, for
the growth of supermassive black holes in galaxy cores, and for the
associated energetic feedback processes. This allows the construction of
complete catalogs of galaxies brighter than 10luminosity in a volume
comparable to those probed by large galaxy surveys like SDSS and 2dF. I
present new results on the small-scale clustering properties of the
predicted galaxy catalogues, on the dependence of clustering on halo
formation time, and on the formation history of elliptical galaxies. I
will emphasize the role of AGN feedback for galaxy evolution, as infered
both from the Millennium simulation and from smaller-scale hydrodynamic
simulations of merging spiral galaxies, which include an explicit
modelling of supermassive black hole growth and associated quasar
feedback.
IBEX: A New Era of Astrophysical Studies Based on Energetic Neutral Atoms (ENAs)
Special Colloquium
Prof. Dave McComas
ORATED
Southwest Research Institute San Antonio (Texas), USA
High velocity O and B type stars have been known since decades. They are
often called runaway stars, as they are moving away at high velocity
from their place of birth in the Galactic plane. None of the runaway O
and B stars were known to have velocities so high as to exceed the
Galactic escape velocity. Only a few months ago the first so-called
hypervelocity star (HVS), a 20th magnitude late B-type star, was
discovered in the Sloan Digital Sky Survey (SDSS) with a radial velocity
of 853 km/s, which exceeds the Galactic escape velocity. Hence the star
is not bound to the Galaxy. Mechanisms for producing run-away stars
(supernova ejection and dynamical ejection) cannot produce ejection
velocities higher than about 300 km/s. A binary encounter with a massive
black hole, however, can accelerate a star to such high velocities, as
already predicted in the late eighties. The Galactic centre, which hosts
a supermassive black hole, therefore is the most likely origin of HVS.
We report the discovery of two other HVS stars not bound to the Galaxy,
which establishes HVS as a class of objects. The first object is a 16th
magnitude early B-type star with a radial velocity of 723 km/s
discovered in the Hamburg-ESO survey, whereas the other one is a
subluminous O star found in the SDSS whose radial velocity is 708 km/s.
Both stars are not bound to the Galaxy. Kinematical experiments are
carried out to investigate their possible places of birth.
Stars on the run: Evidence for super-massive black holes
Main Colloquium
Prof. Uli Heber
ORATED
Sternwarte Bamberg
High velocity O and B type stars have been known since decades. They are
often called runaway stars, as they are moving away at high velocity
from their place of birth in the Galactic plane. None of the runaway O
and B stars were known to have velocities so high as to exceed the
Galactic escape velocity. Only a few months ago the first so-called
hypervelocity star (HVS), a 20th magnitude late B-type star, was
discovered in the Sloan Digital Sky Survey (SDSS) with a radial velocity
of 853 km/s, which exceeds the Galactic escape velocity. Hence the star
is not bound to the Galaxy. Mechanisms for producing run-away stars
(supernova ejection and dynamical ejection) cannot produce ejection
velocities higher than about 300 km/s. A binary encounter with a massive
black hole, however, can accelerate a star to such high velocities, as
already predicted in the late eighties. The Galactic centre, which hosts
a supermassive black hole, therefore is the most likely origin of HVS.
We report the discovery of two other HVS stars not bound to the Galaxy,
which establishes HVS as a class of objects. The first object is a 16th
magnitude early B-type star with a radial velocity of 723 km/s
discovered in the Hamburg-ESO survey, whereas the other one is a
subluminous O star found in the SDSS whose radial velocity is 708 km/s.
Both stars are not bound to the Galaxy. Kinematical experiments are
carried out to investigate their possible places of birth.
The formation and evolution of intermediate-mass stars
Main Colloquium
Dr. Asuncion Fuente
ORATED
Observatorio Astronomico Nacional, Spain
Intermediate-mass young stellar objects (IMs) (protostars and Herbig
Ae/Be [HAEBE] stars with M_* sim 2 - 10 M_{odot}) are crucial in star
formation studies because they constitute the link between low- and
high-mass stars. These objects share many characteristics with high-mass
stars (clustering, PDRs) but their study presents an important
advantage: there are many located closer to the Sun (d leq 1 Kpc), and
in regions less complex than massive star forming regions. On the other
hand, they are also important for the understanding of planet formation
since Herbig Ae stars are the precursors of Vega-type systems. In a
different scale, they dominate the mean UV interstellar field in our
Galaxy (Wolfire et al. 2002). However, IMs have been very little studied
so far. A few works on HAEBE stars have been carried out at millimeter
wavelengths (Fuente et al. 1998,2002; Henning et al. 1998), but almost
nothing is done on their precursors the Class 0 IM objects (see e.g.
André et al. 2000) We have formed a group to study of the structure and
evolution of Class 0 IMs using the largest millimeter telescopes
(IRAM,Effelsberg,APEX,SCUBA,JCMT). In this talk we present a summary of
the status of the project and first resutls.
The host galaxies of nearby quasars: VLT spectroscopy and HST imaging
Main Colloquium
Dr. Pierre Magain
ORATED
Universite de Liege
On-axis VLT spectroscopy has been performed on a sample of 20 bright low
redshift quasars in order to study the properties of their host
galaxies. For some of them, HST images have also been obtained. The MCS
deconvolution method, which has been used to separate the images and
spectra of the central AGN from those of the host galaxy, will be
briefly described. The main results of the study will be discussed:
types of host galaxies, rotation curve, stellar populations, importance
of collisions, ionization of the gas by hot stars or by the AGN, etc...
One of these quasars, HE0450-2958, does not appear to be hosted by a
massive galaxy. The results for this object will be discussed in detail,
as well as their implications on our understanding of the quasar
phenomenon.
APEX - project status after commissioning
Main Colloquium
Dr. Rolf Güsten
ORATED
MPIfR Bonn
Our new sub-millimetre telescope, the Atacama Pathfinder EXperiment, is
now operational on what is probably the world’s best accessible site for
submm observations - Llano de Chajnantor. The antenna is a modified
version of the ALMA prototype built by VERTEX Antennentechnik,
customized to accommodate two Nasmyth cabins for the heterodyne
receivers. The performance of the facility after commissioning will be
summarized. Selected highlights from the science verification will be
presented. The suite of (current and future) instrumentation will be
introduced, with an outlook on next year’s operation.
Basics of supersymmetric theories and of some possible extensions
Special Colloquium
Dr. Adrian Tanasa
ORATED
University of Strasbourg
Supersymmetry is one of most appealing candidates of New Physics beyond
the Standard Model. Leaving aside technical details, we present here the
basic features of supersymmetry as an extension of Poincaré symmetries
of particle physics. In the final part we will briefly present a
possible extension of supersymmetry, namely fractional supersymmetry;
some existing results for this extension are stated.
Formation of Filamentary Molecular Clouds
Main Colloquium
Dr. Fabian Heitsch
ORATED
Institute for Astronomy & Astrophysics, University of Munich
Molecular clouds (MC) are highly structured and “turbulent”. Colliding
gas streams of atomic hydrogen have been suggested as a possible source
of MCs, imprinting the filamentary structure as a consequence of
dynamical and thermal instabilities. We present a numerical analysis of
molecular cloud formation via converging HI flows. Even with modest flow
speeds and completely uniform inflows, non-linear density perturbations
as possible precursors of MCs arise. Thus, we suggest that molecular
clouds are inevitably formed with substantial structure, e.g., strong
density and velocity fluctuations, which provide the initial conditions
for subsequent gravitational collapse and star formation in a variety of
galactic and extragalactic environments.
Consistent Model of the SED of Isothermal Clouds
Special Colloquium
Dr. Joerg Fischera
ORATED
Mt Stromlo Observatory, Australia
The inhomogeneous diffuse interstellar medium of galaxies might have an
important effect on the dust attenuation and the spectral energy
distribution of galaxies. A fraction of the cold neutral medium is
formed in isothermal clouds which are in pressure equilibrium with the
surrounding warm neutral medium. In the ISM of our galaxy these clouds
can be identified with translucent clouds which have typically column
densities in the order of 10^{21} cm^{-2}. I will discuss the SED of
idealised non turbulent isothermal clouds which are heated by the
ambient interstellar radiation field. The radiative transfer problem is
solved using a ray-tracing program to derive realistic light
distributions inside the cloud and to consider non isotropic scattering
and multiple scattering events. The results are based on dust properties
which are consistent with the mean extinction, the diffuse IR-emission,
and the chemical abundances in the ISM. The stochastic nature of the
heating process of interstellar grains is taken accurately into account.
For given radiation field and optical properties of the dust grains the
SED is determined by the outer pressure and the mass fraction
M_{cl}/M_{cl,max} of the cloud mass M_{cl} and the maximum cloud mass
M_{cl,max} where the cloud becomes gravitational unstable. I will show
how the outer pressure and the mass ratio affect the shape of the
thermal emission spectrum and will present brightness profiles at
wavelengths characteristic for the PAH emission and the warm and cold
dust emission.
Stardust: from planetary nebulae to the solar system
Main Colloquium
Prof. Sun Kwok
ORATED
Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan &
University of Calgary, Canada
Recent observations by the Infrared Space Observatory (ISO) have found
evidence of rapid synthesis of complex organic molecules in the late
stages of stellar evolution. The chemical synthesis begins with the
formation of acetylene, the first building block of benzene, in carbon
stars. In a following proto-planetary nebulae stage, emission features
corresponding to stretching and bending modes of aliphatic compounds are
detected. When these objects evolve to become planetary nebulae,
aromatic C-H and C-C stretching and bending modes become strong. These
results show that complex carbonaceous compounds can be produced in a
circumstellar environment over a period of only a few thousand years.
Isotopic analysis of meteorites and interplanetary dust collected in the
upper atmospheres have revealed the presence of pre-solar grains similar
to those formed in evolved stars. This provides a direct link between
star dust and the solar system and raises the possibility that the early
solar system was chemically enriched by stellar ejecta.
Compact Radio Cores in AGN: The X-Ray Connection
Special Colloquium
Matthias Kadler
ORATED
RAIUB & MPIfR
I will present results from an archival X-ray spectral survey of
radio-loud core-dominated AGN. Based on the VLBA 2cm Survey, the
2cm-X-Sample is defined, representing the so far largest sample of
radio-loud AGN being studied in the (0.2–12)keV X-ray regime. The X-ray
characteristics of the 2cm-X-Sample are derived and compared to the
VLBI-monitored parsec-scale jet properties in search of the fundamental
difference between radio-loud and radio-quiet AGN.
Special emphasis will be put on the combined analysis of the available
VLBI and X-ray data of the 2cm-X-Sample source NGC1052. The detection of
a relativistic iron X-ray emission line is reported, which is the first
of its kind in an object with a bright compact radio core. A violent
ejection of relativistic plasma in the radio jet is observed,
accompanied by pronounced variability of the broad iron line: the source
was caught in the act of feeding a part of the accretion disk into the
black hole while a fraction of the material was injected into the jet.
Discovery of radio-transient neutronstars
Main Colloquium
Prof. Dr. Michael Kramer
ORATED
MPIfR
The small fields-of-view of radio telescopes and the short observation
times of most radio surveys mean that the transient radio sky is largely
unexplored. In the largest-scale search ever performed for transient
radio sources, we have discovered a new class of neutron stars. The
eleven new sources are characterized by short, dispersed radio bursts
with average intervals between events ranging from 4 minutes to 3 hours.
So far, no periodicities have been detected in their emission using
standard search techniques, and radio emission is only detectable from
these objects for typically less than one second per day. Nevertheless
we have identified periodicities in the range of 0.4 to 7 s for ten of
the eleven sources. Period derivatives have been measured for four
sources; one with a spin period of 4.3s has an inferred surface dipole
magnetic field strength close to that inferred for high-energy
magnetars. Together with the discovery of a pulsar which shuts down
radio emission quasi-periodically for 30 days, these newly discovered
sources substantially increase the estimated population of Galactic
neutron stars and highlight the rich variety of radio transient sources
that will be discovered with LOFAR or the SKA.
Astrochemistry & Star Formation: Successes and Challenges
Special Colloquium
Prof. Eric Herbst
ORATED
Ohio State University
After a discussion of the current state of knowledge of gas-phase and
grain-surface chemistry, the use of chemistry in understanding the
various stages of low-mass star formation will be outlined. The emphasis
will be on current and past successes as well as on current problems and
future challenges posed by ever more detailed observations.
Bonn-Dwingeloo Neigbhourhood VLBI Symposium
Special Colloquium
Multiple Speakers: Check abstract for details
ORATED
Program Draft - Bonn Dwingeloo Neighbourhood VLBI Meeting
10:45-11:15 Arrival from Dutch Participants and Coffee Welcome
11:15-11:30 Max Avruch et al. VLBI tracking of the Huygens Probe
11:30-11:45 Maria Massi Precession in the Jet of the Microquasar LS I
+61 303 11:45-12:00 Valeriu Tudose et al. Radio observations of the 2004
December 27th flare of SGR 1806-20 12:00-12:15 Kazuya Hachisuka A water
maser outflow in W3 OH 12:15-12:30 Zsolt Paragi et al. Result from the
first continuum e-VLBI experiment 12:30-12:45 Krisztina Gabanyi
Multi-frequency VLBI observations of the scatter-broadened QSO B2005+40
12:45-13:00 Hayley Bignall Structure of the scintillating quasar PKS
1257-326
13:00-14:00 Lunch at the MPIfR Casino (3rd floor)
14:00-14:15 Alicia Berciano-Alba et al. Highly-magnified multiply-imaged
Radio counterparts of the sub-mm Starburst Emission in the Cluster-Lens
MS0451.6-0305 14:15-14:30 Anupreeta More Global VLBI observations of
B2016+112 14:30-14:45 Corina Vogt Rotation measure studies in galaxy
clusters 14:45-15:00 Sang-Sung Lee 86 GHz VLBI surveys of compact radio
sources 15:00-15:15 Olaf Wucknitz Noise in CLEAN Maps 15:15-15:30 Alan
Roy Phase correction of 3 mm VLBI with the Effelsberg WVR
15:30-16:00 Coffee Break (MPIfR entrance hall)
16:00-16:15 Ivan Agudo Rapid Jet Rotation in NRAO 150 16:15-16:30 Andrei
Lobanov Binary Black Holes as Drivers of the Nuclear Activity in
Galaxies 16:30-16:45 Rene Vermeulen Atomic hydrogen in the one-sided
”compact double” radio galaxy 2050+364 16:45-17:00 Violette Impellizzeri
Molecular tori in AGN: a search using excited states of OH 17:00-17:15
James Anderson Radio Emission in Low-Luminosity Active Galactic Nuclei
17:15-17:30 Manuel Perucho A numerical simulation of the fate of a FR I
jet: the case of 3C 31 17:30-17:45 Julianne Sansa Data transfer
challenges for e-VLBI
18:00-19:00 Reception and dinner at the MPIfR Casino (3rd floor)
19:30- Departure of Dutch Participants back to Dwingeloo
GMRT: Study of X-shaped sources
Special Colloquium
Dr. Dharam Vir Lal
ORATED
NCRA, Pune, India
The Giant Metrewave Radio Telescope (GMRT) is a synthesis instrument
operating at frequencies 1.4 GHz and below. The Frequency bands between
1400 and 240 MHz were in use for astronomical observations since 1999.
Although severely affected due to radio frequency interference,
recently, the 150 MHz band of the GMRT is also released for
observations.
Analysis of GMRT low frequency data for an X-shaped source, 3C 223.1 has
revealed an unusual result (Lal & Rao 2005). The radio morphologies of
it at 240 and 610 MHz show a well-defined X-shaped structure with a pair
of active jets along the north-south axis and a pair of wings along the
east-west axis, that pass symmetrically through the undetected radio
core. The wings (or low surface brightness jet) seem to have flatter
spectral index with respect to the high surface brightness jet. We have
now obtained GMRT data for almost all of the X-shaped radio sources,
performed in a uniform way. We would discuss formation models, based on
radio morphologies of these sources and present our current statistical
understanding of the X-shaped radio sources.
Direct imaging of young sub-stellar companions: brown dwarfs and planets
Main Colloquium
Prof. Ralph Neuhaeuser
ORATED
AIU, Jena
The formation of low-mass stars, brown dwarfs, and planets is still a
puzzle. Since several years, we are searching for sub-stellar objects
(brown dwarfs and planets) as companions to young nearby stars, in order
to study their formation. We found and confirmed a few brown dwarf
companions to young T Tauri stars yielding constrains on their formation
mechanism and time-scale. Most recently, we also found a companion to
the 1 Myr young classical T Tauri star GQ Lupi, which may even be a
few-Jupiter-mass planet according to our indirect mass determination. In
the talk, we will present all our observational evidence on GQ Lupi and
its companion to discuss its mass and nature. If it is a planet, then
planets can form fast.
Eta Carinae: how can we see its companion?
Special Colloquium
Dr. Theodore Gull
ORATED
Goddard Space Flight Center, Greenbelt, USA
In the 1840’s, astronomers witnessed Eta Carinae brightening to rival
Sirius. Today we see a expanding dusty hourglass-shaped Homunculus.
Internal is an ionized Little Homunculus, ejected in the 1890’s. Between
the bipolar lobes lies an extended disk structure. Part of this is the
Strontium Filament, a neutral emission region seen in hundreds of metal,
but no hydrogen, lines. Within a thousand AU, a necklace of bright
clumps surround the central source. Three of these are the partially
ionized Weigelt clumps, rich in emission lines of iron-peak elements.
Lyman-alpha-pumped Fe II lines, seen for five year intervals, disappear
for a few months every 5.54 years. Multiple shells are seen in
absorption against the central source and the nebular scattered
starlight.
What is this telling us about the central source? Models of the Weigelt
clump emission indicate that the UV flux from a 35,000K O star is
necessary to support their emission. N and He are overabundant; C and O
are nearly absent. Models of the Sr Filament indicate that lack of O
leads to many metals, such as Sr, V and Ti usually bound as oxides to
normal interstellar dust, staying in gaseous phase. The Homunculus and
Little Homunculus contain at least twelve solar masses of gas. The X-ray
bright outer structure - likely from a previous event - indicates even
more mass lost in the past. Recently a faint [O III] emission structure
much further out is thought to indicate the wind interaction boundary
with the interstellar medium.
The primary star is thought to be about 100 solar masses. The companion,
whether an O star, an ON or WN star, appears to be about 30 solar masses
based upon its UV flux and on wind-wind models of the X-ray
spectroscopy. The companion’s orbit is estimated to be highly elliptical
with a major axis approaching 20 AU (9 milliarcseconds X cos(inclination
angle)). What observation will lead to detection of this companion?
Mixer, detector development at Caltech and the Cornel Caltech Atacama telescope
Special Colloquium
Prof. Jonas Zmuidzinas
ORATED
Caltech, Pasadena, USA
The Giant Metrewave Radio Telescope (GMRT) is a synthesis instrument
operating at frequencies 1.4 GHz and below. The Frequency bands between
1400 and 240 MHz were in use for astronomical observations since 1999.
Although severely affected due to radio frequency interference,
recently, the 150 MHz band of the GMRT is also released for
observations.
Analysis of GMRT low frequency data for an X-shaped source, 3C 223.1 has
revealed an unusual result (Lal & Rao 2005). The radio morphologies of
it at 240 and 610 MHz show a well-defined X-shaped structure with a pair
of active jets along the north-south axis and a pair of wings along the
east-west axis, that pass symmetrically through the undetected radio
core. The wings (or low surface brightness jet) seem to have flatter
spectral index with respect to the high surface brightness jet. We have
now obtained GMRT data for almost all of the X-shaped radio sources,
performed in a uniform way. We would discuss formation models, based on
radio morphologies of these sources and present our current statistical
understanding of the X-shaped radio sources.
The Intricate Process of US Science Funding: An Introduction
Main Colloquium
Dr. Kevin B. Marvel
ORATED
Deputy Executive Officer, American Astronomical Society
From Europe, the process of how the United States funds scientific
research often seems confusing, short-sighted and non-stable.
Appearances can be deceiving. The US government is a firm supporter of
basic research and will remain so into the future. Policy makers are in
agreement that supporting basic research is the best way to secure a
good quality of life for its citizens. I will present the basic process
of how astronomy research is funded in the United States including
describing in detail the funding outlook for the coming year and
discussing current policy issues of importance to astronomy. Plenty of
time will be available for questions.
Distances to High Velocity Clouds
Special Colloquium
Christopher Thom
ORATED
Swinburne University of Technology, Australia
High Velocity Clouds are clouds of neutral hydrogen which do not conform
to simple models of galactic rotation. Since such kinematic models
cannot be used to infer their distances, other more direct methods are
needed. I will present a catalogue of stars which may used to constrain
HVC distances directly. We have obtained high resolution spectroscopic
observations of such stars, and some preliminary results will be
presented. Such observations will allow us to disentangle the multiple
origin scenarios.
Jet-induced Star Formation in the Early Universe
Special Colloquium
Ilana Klamer
ORATED
Australia Telescope National Facility, Epping, Australia
TBA
Searching for the Youngest Brown Dwarfs and Low-Mass Protostars with Spitzer
Informal Colloquium
Dr. Tracy L. Huard
ORATED
Harvard-Smithsonian Center for Astrophysics
The Cores-to-Disk Spitzer Legacy team has discovered a mid-infrared
source, L1014-IRS, with protostellar colors embedded in a molecular
cloud core previously thought to be starless. This source is faint
enough that it evaded detection by previous observations, and is
consistent with being either a young substellar source or a low-mass
protostar early in its formation. The Spitzer Space Telescope is
sensitive enough that such sources can now be detected. Preliminary
results of a search for sources similar to L1014-IRS, and the
implications of these results, will be presented.
Report on Receiver Developments at the CSIRO
Special Colloquium
Graham Moorey
ORATED
CSIRO
TBA
The Cosmogony of Super-Massive Black Holes
Main Colloquium
Prof. Wolfgang J. Duschl
ORATED
Institut für Theoretische Astrophysik, Universität Heidelberg
Recent surveys, both in the optical and, in particular, in the X-ray
regime, indicate that the most massive black holes (for instance in
quasars) must have formed earlier and quicker than less massive ones. We
show that the rapid formation of super-massive black holes in quasars
can indeed be understood in terms of major galaxy mergers followed by
disk accretion. Weaker galaxy interactions lead to less compact and less
massive accretion disks which take considerably longer to grow a
(consequently less massive) black hole. Due to the expansion of the
cosmos, strong interactions become less likely with time and thus lead
to the formation of fewer and fewer very massive black holes.
The Formation of Massive Stars and Star Clusters
Main Colloquium
Dr. Jonathan Tan
ORATED
ETH Zuerich
I review some recent developments in our attempts to understand massive
star and star cluster formation. Both processes can be understood with a
model involving the formation and collapse of gas cores from a highly
pressurized and turbulent medium. Given these initial conditions we can
make predictions for the properties of the collapsing cores, accretion
disks, protostars and their outflows. The interaction of protostellar
ionizing flux with the mainly neutral protostellar outflow produces a
hypercompact HII region, which is a particularly useful diagnostic. We
test these models by comparing to some well-studied regions,
particularly in the Orion Nebula Cluster. We argue that while individual
star formation occurs rapidly on a local freefall time ( 10**5 years),
the time to build up an entire star cluster is much longer ( few x 10**6
yr). Finally we emphasize the importance of the dynamical ejection of
massive stars, as illustrated by the recent example involving the
Becklin-Neugebauer object in Orion.
Radio astronomical probes of cosmic reionization
Main Colloquium
Dr. Chris Carilli
ORATED
NRAO, Socorro, NM, USA
The epoch of reionization (EoR) corresponds to a ’cosmic phase
transition’, when the neutral intergalactic medium (IGM) becomes ionized
by the first stars and/or AGN. While the discoveries of Gunn-Peterson
(GP) absorption troughs in the spectra of the highest redshift QSOs, and
large scale polarization of the CMB, have set the first constraints on
the EoR, the process of reionization, and the nature of the first
luminous objects, remain two of the paramount questions in cosmic
structure formation. Moreover, the GP effect is such that observations
of this epoch will be difficult at wavelengths shorter than about
1micron. In this talk I will explore studies of the EoR at meter through
millimeter wavelengths. I will present recent observations of the dust,
molecular gas, and star formation activity in the host galaxies of the
highest redshift QSOs (z>6). These results have interesting implications
on the timescale for metal and dust enrichment, on the possibility of
co-eval formation of SMBHs and galaxies, and on the process of
reionization. I will then discuss future capabilities of low frequency
radio astronomy to study the neutral IGM via the HI 21cm line, including
details on the VLA-VHF project to image the cosmic Stromgren spheres
around the highest redshift objects.
Gravitational Waves from Black Holes in Star Clusters
Special Colloquium
Prof. Fred Rasio
ORATED
Northwestern University, USA
Dynamical interaction processes occurring in dense star clusters lead to
the formation of many of the most interesting types of gravitational
wave sources for both ground-based and space-based interferometers (eg
GEO, VIRGO, LIGO, and LISA). In this talk I will present some recent
results on the production of two types of sources: merging stellar black
hole binaries, which are one of the main targets for ground-based
detectors, and inspirals of intermediate-mass black holes into
supermassive black holes in galactic centers (key sources for LISA).
Constraints from and implications for our own Galactic center will also
be discussed.
Herbig Ae disks at 10 micrometer: disk structure and dust evolution
Special Colloquium
Dr. Roy van Boekel
ORATED
MPIA Heidelberg
TBA
Binary black hole systems in active galactic nuclei
Special Colloquium
Prof. Jacques Roland
ORATED
Institut d'Astrophysique, Paris, France
A large fraction of active galactic nuclei (AGN) exhibit a number of
quasi-periodic changes indicative of the presence of binary systems of
supermasive black holes. We discuss here the hypothesis that most of the
AGN contain supermassive binary black hole systems, in which the orbital
motion and precession are ultimately responsible for the observed
broad–band emission variations, as well as for the morphological and
kinematic properties of the radio emission on parsec scales. We present
a new method to determine the characteristics of the binary black hole
systems from observations of optical variability and changes of compact
radio structure. We apply this scenario to explain the compact radio and
optical emission in the quasar 3C345, and discuss the general
applicability of this model to studies of AGN and galactic X-ray
binaris.
The Origin of Turbulent Molecular clouds and their Condensation into Stars and Stellar Clusters
Main Colloquium
Prof. Dr. Andreas Burkert
ORATED
Ludwig-Maximilians University Munich
The formation of stars is still one of the most important unsolved
astrophysical problems. It is now well established that stars form in
turbulent and clumpy giant molecular clouds. However the origin of these
structures, their lifetimes and stability and the processes that lead to
their condensation into star clusters are not understood theoretically.
I will summarize theoretical work in this field which is based on
high-resolution numerical hydrodynamical simulations and will present
new results of the computational astropysics group at the University
Observatory Munich which focus especially on the origin of filamentary
molecular clouds and their star formation history.
The chemical evolution of the dwarf galaxy NGC 1569
Main Colloquium
Dr. Simone Recchi
ORATED
University of Vienna
Blue Compact Dwarf and Dwarf Irregular galaxies are generally believed
to be unevolved objects, due to their blue colors, compact appearance
and large gas fractions. Many of these objects show an ongoing intense
burst of star formation or have experienced it in the recent past. By
means of 2-D hydrodynamical simulations, coupled with detailed chemical
yields originating from SNeII, SNeIa and intermediate-mass stars, we
study the dynamical and chemical evolution of model galaxies with
structural parameters similar to NGC1569, a prototypical starburst
galaxy. A burst of star formation with short duration is not able to
account for the chemical and morphological properties of this galaxy.
The best way to reproduce the chemical composition of this object is by
assuming long-lasting episodes of star formation and a more recent
burst, separated from the previous episodes by a short quiescent period.
The last burst of star formation, in most of the explored cases, does
not affect the chemical composition of the galaxy, since the enriched
gas produced by young stars is in a too hot phase to be detectable with
the optical spectroscopy. Models assuming the infall of a big cloud
towards the center of the galaxy reproduce the chemical composition of
the NGC1569, but the pressure exercised by the cloud hampers the
expansion of the galactic wind, at variance with what observed in
NGC1569.
The infancy of massive stars
Main Colloquium
Dr. Lex Kaper
ORATED
University of Amsterdam
Using the highest spectral resolution (R sim 10,000) currently
available in the near-infrared on the Very Large Telescope, we have
obtained K-band spectra of young massive stars deeply embedded in
(ultra-) compact H II (UCHII) regions. Our sample consists of “normal”
OB-type stars that seem to have settled on the main sequence, as well as
massive stars that show no photospheric spectrum, but exhibit the
spectral signatures of a dense circumstellar disk. We present arguments
that these objects are massive young stellar objects. One of the main
results of our accompanying near-infrared imaging survey is that the
large majority of IRAS sources with UCHII colours correspond to young
(embedded) clusters, rather than to UCHII regions. This may well solve
the UCHII lifetime problem.
IMPRS Lecture: Wavelets - An Analysis Tool for Astrophysical Data
Special Colloquium
Prof. Peter Frick
ORATED
Institute of Continuous Media Mechanics, Perm, Russia
The lecture includes a short basical introduction into the wavelet
analysis and an overview of some data treatment problems which are
suitable for wavelet techniques: differentiation of noised data,
nonstationary spectra analysis, scale by scale cross-correlations,
analysis of data with gaps, examples of DWA (double wavelet analysis)
technique - determination of stellar rotation period and of
anharmonicity of stellar cycles, 2D maps analysis using isotropic and
anisotropic wavelets.
Eine neue Polarisationskartierung des noerdlichen Himmels bei 1.4 GHz.
Special Colloquium
Maik Wolleben
ORATED
MPIfR
A new FPGA-based wide-band polarimeter has been developed at DRAO to be
used on the DRAO 26-m Telescope. The polarimeter is capable of sampling
two input channels with a sampling frequency of 1 GHz and 8 bit
resolution. It is currently being used for the new DRAO-MPI Rotation
Measure Survey, which covers the northern sky in the frequency range
1300 to 1800 MHz. I will discuss its implementation, capabilities, and
limitations, as well as the objective for the new rotation measure
survey.
The AGN obscuring torus - is it really a "bagel"?
Main Colloquium
Dr. Moshe Elitzur
ORATED
Department of Physics and Astronomy, University of Kentucky, U.S.A.
The variety of observations of Active Galactic Nuclei (AGN) have been
classified with a simple unified scheme: The nuclear activity is powered
by a central massive black hole that drives radio emitting jets and
ionizes surrounding line-emitting clouds. The whole system is surrounded
by a dusty torus and the observer’s orientation with respect to this
obscuring torus determines the appearance of the AGN. Pole-on viewing
gives rise to superluminal jets and Seyfert 1 line spectrum, edge-on
results in extended radio lobes and Seyfert 2 lines. The torus is
comprised of optically thick dusty clouds in a rotating configuration
with roughly equal vertical and radial dimensions.
Although the observed IR is in broad agreement with the expected effects
of the dusty torus, detailed properties of the spectral energy
distribution (SED) posed difficult problems. The dynamical origin of the
rotating cloud configuration, and especially the maintenance of its
vertical height, present an even more serious challenge. We have
recently developed a formalism to handle radiative transfer in clumpy
media and in this talk I show that the SED problems find a natural
explanation if the dust is contained in about 5–10 clouds along radial
rays through the torus. Furthermore, the properties of the model SED may
also provide the answer for the torus dynamical origin.
X-Ray Studies of Galaxy Cluster Structure
Special Colloquium
Prof. Hans Böhringer
ORATED
MPE, Garching
The observational constraints of the cosmological model that fits our
Universe is reviewed and the prerequesites for these constraints are
discussed. Particular emphasis is given to the cosmological tests using
the galaxy cluster population. Besides current results, future prospects
with an X-ray survey with eROSITA are pointed out.
Gas and dust condensations and an embedded object in the Lupus star forming clouds
Special Colloquium
Dr. Kengo Tachihara
ORATED
University of Jena
The Lupus molecular cloud complex is a nearby star forming region which
shows large variety of different modes of star formation such as active
cluster formation, isolated star formation, and starless clouds. The
region has been surveyed for molecular clouds in
m ^{12}CO,
m ^{13}CO, and
m C^{18}O entirely by the NANTEN radio telescope, and
the embedded
m C^{18}O cores have been almost completely sampled. We
have then searched for even denser (n({
m H_2}) > 10^5 cm^{-2}) gas and
dust condensations in the cores and found 10
m H^{13}CO^+ cores by
SEST. The
m H^{13}CO^+ cores are well traced by near-IR extinction map
whose Av is greater then 30 mag. Further follow-up observation in 1.3 mm
dust continuum detected an embedded point source besides the molecular
cloud and cores in Lupus 3. The SED of this mm point source shows very
low temperature and low luminosity suggesting that it is a very young
protostar called class 0 object. The K- band image shows jet-like
structure coming out of the mm point source. Base of these observational
results, I will discuss general properties of star formation in Lupus
and future survey project in the southern sky.
Orion Unveiled in the near Infra-Red
Special Colloquium
Prof. David Field
ORATED
University of Aarhus, Denmark
The Orion Molecular Cloud, OMC1, is a type-site for high and low mass
star formation. Winds from massive stars, identified in the IR and in
radio observations, perturb the gas giving rise to spectacular outflows
with velocities ranging from a few km/s to several hundred in the outer
reaches of the cloud. Resulting shocks compress the gas and create a
scenario of “”triggered star formation“”, which may contribute to the
nearly one thousand young stars of similar age in the Orion region. Less
energetic outflows associated with protostars may also be identified in
OMC1, one or two with a bipolar form, but in several cases with 6 or 8
apparent outflows, presumably associated with multiple star formation.
Our understanding of this complex region has been greatly enhanced
through the very high spatial resolution afforded by adaptive optics
(AO) in the near-IR. This allows us to isolate specific clumps of gas
and study shocks, photodissociation regions and outflows with a minimum
of spatial overlap. I will describe data for H2 IR emission in the
K-band (2-2.5micron) which records both morphology at a spatial
resolution of 60-70 AU, using the VLT, and velocities of the gas, with a
velocity discrimination as good as 1 km/s, using the
Canada-France-Hawaii Telescope. These data reveal the presence of
magnetic shocks in a graphic manner and open a new window into the
structure of this highly active star-forming zone. The data also
highlight the need for high spatial resolution radio observations of the
cold gas component.
Methanol masers as diagnostic tools
Special Colloquium
Dr. Andrej Sobolev
ORATED
Astronomical Observatory, Ural State University, Ekaterinburg, Russia
Methanol masers arise in the regions of massive star formation and can
tell a lot about their properties and the processes in them. Several
topics of the use of methanol masers as diagnostic tools will be
discussed. Maser pumping is very sensitive to the parameters of the
region of maser formation and its environment. Observations of multiple
masing transitions provide good constraints on the physical parameters.
Temperatures, densities, column densities and even dust composition are
among those. Extensive surveys in different lines allow to construct a
picture of the “common” methanol maser region. Interferometric maser
images provide information on the distribution and kinematics of masing
gas on small spatial and time scales. This puts constraints on the sizes
and structure of the maser regions and allows tracing motions, including
turbulent ones. Long term monitoring with single-dish antennas helps
reveal the evolution of the maser profiles and intensities over long
periods of time. Character of variability of the methanol masers greatly
varies from source to source. Different possible causes of this
variability do exist. Analysis of those shows that the variability of
class II methanol masers reflects the character of accretion processes
onto massive young stellar objects. A unified catalogue of the class II
methanol masers is compiled. The luminosity function and observed maser
distribution in the Galaxy are constructed. Velocity correlations
between masers and tracers of high density molecular material are
analysed. Analysis of the data shows that the class II methanol masers
have high potential for the studies of the spiral structure of our
Galaxy, reflect grand design and evolutionary stage of the massive star
forming regions.
The Vela supernova remnant in the Southern Galactic Plane Survey
Special Colloquium
Dr. Marijke Haverkorn
ORATED
CfA, Cambridge, USA
The Southern Galactic Plane Survey (SGPS) is a radio survey in the
neutral hydrogen line and full-polarization continuum at 1.4 GHz. It
spans 253 < l < 20 and |b| < 1, with a resolution of about an arcminute.
Part of the Vela supernova remnant (SNR) is prominently present in the
radio polarization data, which reveals new clues about Vela’s structure
and magnetic field. I will discuss radio, optical and X-ray data in the
North-Eastern shell of Vela proper, giving information about the
supernova shock and the surrounding interstellar medium. Furthermore, I
will discuss magnetic field structure in the Vela SNR and the protrusion
outside the shell called Bullet D. Finally, our data give an independent
lower limit for the distance of SNR G266.2-1.2 (Vela Junior).
Gamma-Ray Bursts in the Swift era
Main Colloquium
Dr. Jochen Greiner
ORATED
MPE, Garching
I will review the status of gamma-ray burst knowledge with particular
emphasis on Swift. Swift is a dedicated GRB afterglow satellite launched
by NASA in Nov. 2004. I will review first results from Swift, and
discuss expectations for the future. In the second part of the talk I
will report on our efforts at MPE to build a 7-channel
optical/near-infrared camera to be placed at the 2.2m MPG/ESO telescope
with the aim to chase Swift-detected GRB afterglows.
Multi-wavelength interferometry of evolved stars using VLTI and VLBA
Special Colloquium
Dr. Markus Wittkowski
ORATED
European Southern Observatory, Garching
I present recent results on stellar atmospheres and circumstellar
environments of evolved stars obtained with optical/infrared and radio
long-baseline interferometry. I demonstrate the advantages of a
coordinated multi-wavelength approach including near/mid-infrared as
well as radio (and millimeter) interferometry to further our
understanding of the extended atmospheres, of the mass-loss process from
evolved stars, and ultimately of the evolution of AGB stars toward
planetary nebulae.
Einstein and Cosmology
Main Colloquium
Prof. Jürgen Ehlers
ORATED
AEI, Hannover
As a scientific activity with interactions between observation and
theory, cosmology has two roots. Observationally it started with
Slipher’s measurements of extra galalctic red shifts in 1913 ,
theoretically it began with Einstein’s static, spherical model universe
of 1917 which was based on his general relativity theory, augmented by
the lambda term. Einstein paricipated in cosmological discussions in
1918, 1931 and around 1945. I shall describe some of his work,
emphasizing topics of lasting interest, such as the time scale, dark
matter and lambda.
Sunyaev Zel'dovich galaxy cluster surveys
Special Colloquium
Dr. Jörn Geisbüsch
ORATED
College de France, Paris
Galaxy clusters are the largest gravitationally collapsed objects in the
universe. A unique way to detect them is the Sunyaev-Zel’dovich (SZ)
effect - a Cosmic Microwave Background (CMB) imprint due to inverse
Compton scattering of the CMB photons off the cluster electron gas. Just
recently it has become feasible to build instruments capable of
conducting blind SZ cluster surveys. The talk will motivate the use of
such SZ cluster surveys as a cosmological tool. Upcoming SZ survey
instruments and their abilities will be discussed on the basis of
simulations. Methods to overcome data analysis challenges will be
introduced and preliminary predictions about parameter constraints will
be shown.
How to produce the interstellar extinction from nothing?
Special Colloquium
Prof. Nikolaj Voshchinnikov
ORATED
St. Petersburg University, Russia
A serious challenge to dust modelling in last years is related to a
steady decrease of estimates of solar (cosmic) abundances of metals.
This calls for new dust models able to produce the same extinction with
a less amount of solid material. A solution to the problem could be
provided by the inclusion of vacuum (nothing) as a component of
interstellar grains.
It will be shown how to describe the optics of porous particles and how
the porosity (fluffiness) of dust grains influences on interstellar
extinction, dust temperature, infrared features, etc.
Imaging Spectroscopy with mas-resolution: new opportunities with VLT, Keck and ELTs
Main Colloquium
Prof. Alfred Krabbe
ORATED
1. Physikalisches Institut, Universität Köln
Imaging spectroscopy in the NIR can take full advantage of adaptive
optics assisted diffraction limited imaging available at large optical
telescopes. Two newly deployed spectrographs, SINFONI at the VLT and
OSIRIS at the Keck,are already showing remarkable results. A study for a
similar instrument at the interferometric focus of the LBT (using
LINC-NIRVANA) has already been started. Itsprojected angular resolution
of 10mas will be 30 times better than current non-AO assisted
instruments capabilities. It will be the first operating NIR
spectrograph at an ELT and will open up a new exciting window for NIR
imaging spectroscopy.
Measuring the Polarization of the Cosmic Microwave Background CAPMAP and QUIET
Special Colloquium
Dr. Dorothea Samtleben
ORATED
Kavli Institute, Chicago University
The Cosmic Microwave Background (CMB) is radiation which was released
400000 years after the Big Bang and contains a wealth of cosmological
information. Its spectrum has been measured with extraordinary precision
and its spatial anisotropy has been very well characterized, with WMAP
providing the most comprehensive results. There are two distinct
patterns to the polarization of the CMB, conventionally termed E- and
B-modes. Characterization of the E-mode power spectrum is important for
testing the understanding of the origin of the CMB as well as for
breaking degeneracies in cosmological parameter determinations.
The B-modes are expected to be at least an order of magnitude smaller
and can be produced by gravity waves from the inflationary epoch as well
as from lensing of E-modes. The amplitude of the gravity waves as seen
in the CMB is linked to the energy scale of inflation which may also be
the GUT scale. Measurements of the lensing contribution can provide
limits on neutrino masses. The CMB polarization measurements thus have
exciting prospects for opening new windows to fundamental physics.
CAPMAP is an experiment measuring the E-mode CMB Polarization in the
angular range from 5’ to 40’ with multiple 90 GHz and a few 40 GHz
correlation receivers on the 7m Crawford Hill telescope. The techniques
of polarization measurements and the implementation for CAPMAP will be
described. The latest results from CAPMAP will be presented as well as
the overall status and future of CMB polarization measurements. The
potential for the successor of CAPMAP will also be shown: the experiment
QUIET, a large polarimeter array, using miniaturized correlation
polarimeters. QUIET will increase the sensitivity of current experiments
to unprecedented precision.
Molecular Cross Section of the Milky Way
Special Colloquium
Carolin Hieret
ORATED
MPIfR Bonn
On the galactic scale, molecular clouds have a low density (n 200cm-3)
and temperature (T 10K). Their chemistry is known to contain the easily
observable CO molecule. Little is known about the abundances of other
molecul es, whose low columnn densities make them difficult to observe.
In this talk I will report on a study of the chemical compositions in
diffuse molecular clouds along the line-of-sight towards SgrB2(M). The
Giant Molecular Cloud SgrB2 is located in the Central Molecular Zone, at
a projected distances of 100 pc away from the Galactic Center. It hosts
several compact and ultra compact HII regions, which emit strong
continuum emission. This continuum emission can be used as a background
source to study the absorption of gas along the line of sight towards
SgrB2. We have conducted a survey over the complete 3mm band towards the
two cores, SgrB2(M) and SgrB2(N), resulting in a plethora of absorption
and emission lines. Out of this data, I have studied lines that show
absorption against SgrB2(M). They appear at velocities which show little
contamination by emission from SgrB2 itself. The absorption arising
along the line of sight can be divided into features originating in the
cold and dense molecular envelope around the SgrB2(M) core and features
arising from diffuse clouds (n 200cm-3) located between us and the
Galactic Center. Absorption lines are our only means to study those
clouds, since the low densities prevent rotational levels from being
thermally excited, with excitation temperatures as low as the 2.7K
cosmic background. According to chemical models, there should only be a
simple chemistry found in those low density clouds, but studies,
including our own, have shown that the observed species are a lot more
complicated than the chemistry allows for.
Hydroxyl Masers in Massive Star Forming Regions
Special Colloquium
Dr. Vincent Fish
ORATED
NRAO Socorro
I present full-polarization VLBA images of 1665 and 1667 MHz hydroxyl
(OH) masers in massive star forming regions. Magnetic fields deduced
from Zeeman splitting suggest organized field structures with at most
one line-of-sight field direction reversal in each source, suggesting
that the magnetic field is not highly twisted by the process of star
formation. Correlations between magnetic field directions around star
forming regions separated by kiloparcsecs have implications for the
Galactic magnetic field. The clustering and ages of OH masers are
consistent with the location of OH masers in the ionization-shock front
zone around a central ultracompact H II region. I discuss the
significance of linear polarization as well as possible complications
arising from Faraday rotation.
Recent progress on the VSOP-2 Mission
Informal Colloquium
Dr. Yoshiaki Hagiwara
ORATED
ASTRON
This talk will outline the next generation space radio Very Long
Baseline Interferometry (VLBI) mission, VSOP-2. Following the successes
of the VLBI Space Observatory Programme (VSOP) mission, which was
realized with the launch of the HALCA satellite in 1997, the VSOP-2
mission is being planned in Japan in collaboration with international
partners for a launch in 2011 at this present. The mission has not yet
been approved in ISAS/JAXA and staffs in National Astronomical
Observatory of Japan (NAOJ) are collaborating with the ISAS VSOP-2 team
to support and promote the VSOP-2 project. The scientific objectives
include high angular resolution imaging of the jets and accretion disks
of AGN, Galactic and extra-galactic water maser sources, and the coronae
of YSO. The observing bands will be 8, 22, and 43 GHz and an highest
achievable angular resolution will be 38 micro-arcseconds at the 43 GHz
band. The VSOP-2 spacecraft will employ a 9 m off-axis paraboloid
antenna with dual polarization.
The VSOP-2 mission was realized through a large international
collaboration in terms of large ground telescopes such as MPIfR
Effelsberg Telescope, correlators, and tracking stations, and a similar
degree of collaboration with European institutes/astronomers, including
MPIfR staffs and the 100-m telescope, will be essential for the success
of VSOP-2.
High-mass star formation in the Southern Hemisphere sky
Main Colloquium
Dr. Vincent Minier
ORATED
CEA, Saclay, France
We report on a multi-wavelength (IR to cm) and multi-resolution (1 mas
to 20 arcsec) exploration of high-mass star formation regions in the
Galactic plane, at longitudes observable from the Southern Hemisphere.
Our source sample was originally identified through methanol masers in
the Galactic plane, which exclusively trace high-mass star-forming
regions. (Sub)millimetre continuum and molecular line observations were
carried out with SEST/SIMBA, JCMT/SCUBA and the ATNF/Mopra mm-wave
telescope and have allowed us to identify massive (>20 Msolar) and
luminous (>10^3Lsolar) clumps in each star-forming region. We have also
constrained the SED with additional archives IR data, the physical
conditions (Td, L, M) and the chemical composition of each massive
clump. Several types of objects were characterised based on the ratio
Lsubmm/Lbol, the dust temperature and the molecular line properties,
ranging from class 0-like YSO clusters (Lsub/Lbol>1%, Td=30 K) to hot
molecular cores (Lsub/Lbol=0.1%, Td=40-200 K). Preliminary high-angular
resolution observations for a subset of the sample with the ATCA at 3
mm, the VLA at 15, 22 and 43 GHz and Gemini in MIR have revealed that
several (proto)stellar objects are embedded in the massive clumps:
massive protostars, hot cores and hyper compact HII regions. We have
thus identified protoclusters of massive YSOs, which are the precursors
of the OB associations. This sample of Southern Hemisphere star-forming
regions will be extremely valuable for the scientific preparation of
ALMA and HSO observations.
A spin-powered pulsar-like white dwarf in the close binary AE Aquarii
Main Colloquium
Dr. Nazar Ikhsanov
ORATED
Pulkovo Observatory & Korea Astronomy and Space Science Institute
AE Aquarii is a close binary system which emits detectable radiation in
all parts of the spectrum (from radio up to gamma-rays). The system
components are a main sequence red dwarf and a fast rotating white
dwarf. The appearance of the system does not allow us to assign it to
any of presently known classes of close binaries. In particular, it is
well established that the mass transfer in this system operates via the
Roche lobe overflow mechanism, but the material transferred from the
normal companion is neither accreted onto the surface of the white dwarf
nor stored in a disk around its magnetosphere. Moreover, the energy
budget of the system is dominated by the spin-down power of the white
dwarf, which exceeds the bolometric luminosity of the system by a factor
of a few. Finally, the system shows flaring activity whose properties
are absolutely unique among all classes of flaring astrophysical
objects. In my talk I overview the basic properties of the system and
discuss the models suggested for their interpretation.
MRI and SRI in accretion disks and for laboratory experiments
Main Colloquium
Prof. Günther Rüdiger
ORATED
Astrophysikalisches Institut Potsdam
The magnetorotational instability (MRI) and the stratorotational
instability (SRI) are the main candidates for the generation of
turbulence in accretion disks. Also the Hall effect can destabilize
differential rotation by an own instability reducing the critical
magnetic Reynolds number in Kepler disks by one order of magnitude. For
cold material, however, the combination of vertical density gradients
and radial differential rotation in Taylor-Couette experiments leads to
the excitation of global and spiral modes. New simulations for both the
instabilities are presented together with calculations about the
possible first experimental realization of the MRI.
Reionization imprints on the CMB - From WMAP to future projects
Special Colloquium
Dr. Carlo Burigana
ORATED
INAF/IASF, Sezione di Bologna
One of the most relevant discoveries of WMAP is the detection of a high
redshift reionization through its imprints on CMB anisotropy T and TE
mode angular power spectra. The CMB offers a particular view of the
reionization process, being sensitive to the integrated history of the
ionized medium. On the other hand, the accurate analysis of the CMB
spectrum and anisotropies provides significant constraints also on the
details of reionization since different reionization mechanisms predict
different signatures in the CMB, both in temperature and polarization
anisotropies at different angular scales and in spectral distortions at
high and low frequencies. The Planck capability to distinguish among
different scenarios and constrain the physical properties of specific
models through its sensitivity to T, TE, and E mode angular power
spectra is discussed. Perspectives open by future high sensitivity
experiments on the CMB polarization anisotropy and spectrum are also
presented. Finally, the information contained in the CMB is compared
with that expected by future accurate ground observations at radio
frequencies, in particular by SKA and LOFAR.
CW THz generation using a 2-colour laser and THz applications at
Leeds
Special Colloquium
Dr. Mira Naftaly
ORATED
University of Leeds, UK
A simple scheme for generating continuous-wave (CW) terahertz (THz)
radiation from a two-colour laser has been developed in Leeds. A
Ti-sapphire laser is forced to oscillate on two modes by placing a
Fabry-Perot etalon in the laser cavity. THz radiation corresponding to
the difference frequency of the modes is generated by photomixing in a
biased photoconverter. The THz frequency is determined by the free
spectral range of the etalon and can be varied by changing its plate
separation. The design and performance of the CW THz system will be
described in detail. The second part of the talk will describe other
work on THz applications in Leeds, and will present results on THz
transmission and reflection spectroscopy in a variety of materials.
Properties of HI selected Galaxies
Special Colloquium
Dr. Diego Garcia-Appadoo
ORATED
Cardiff University
I will present an overview of galaxies detected in the HIPASS survey,
the first all HI sky survey at 21 cm. Together with SDSS data we’ve
discovered some fascinating objects including the 1st ”Dark Galaxy”.
New Results from the SCUBA Local Universe Galaxy Survey, (SLUGS)
Special Colloquium
Dr. Catherine Vlahakis
ORATED
Cardiff University
New Results from the SCUBA Local Universe Galaxy Survey (SLUGS) the
optically-selected sample. An investigation of dust in nearby ”normal”
galaxies, free from dust temperature selection effects.
Spitzer Space Telescope observations of nearby star-forming clouds
Special Colloquium
Prof. Ewine van Dishoeck
ORATED
Leiden Observatory
TBA
Optical Detection and lensing analysis of clusters of galaxies
Informal Colloquium
Patrick Hudelot
ORATED
Observatoire de Toulouse
Clusters of galaxies are the most massive gravitationnaly bound objects
in the universe. Therefore they are important tools for cosmology,
providing information on the large scale dark matter distribution and
the evolution of the universe. I will first present my work on
gravitationnal lensing, and in particular new tools to measure the shape
of galaxies and reconstruct the mass distribution in clusters using
lensing constrains. This new software has been used on the HST/WFPC
mosaic of Cl0024 and Abell 2218. I will then present a collaboration
with Cambridge on cluster detection. CFH12K and MEGACAM optical images
and AMI SZ maps will be used to detect clusters and analyse them. The
optical method we chose (red cluster sequence) will be explained.
Finally I will briefly present an update on the CFHT Legacy Survey.
Tracing the Velocity Fields of Dense Cores
Special Colloquium
Dr. Nikolaus Volgenau
ORATED
Universität Köln
Although the theory of low mass star formation that had developed over
the past several decades is quantitatively rigorous, it can only explain
a fraction of real star-forming events. The motivation for our work is
the hypothesis that turbulence is fundamental to the star formation
process. We present evidence, from observations of dense cores in the
Perseus cloud made with the BIMA interferometer and the FCRAO 14m
antenna, that turbulent motions persist within the characteristic core
radius (0.1 pc) identified in lower resolution studies. In general, the
range of velocities traced by our molecular line emission maps, as well
as the complexity of the fields, increases with resolution. No core
resembles a quiescent condensation undergoing simple systematic
rotation. In addition, a statistical analysis of the variations in line
properties as a function of spatial separation indicates a hierarchy of
turbulent gas motions.
Die Suche nach hochdispergierten Radio-Pulsaren in Richtung des Galaktischen Zentrums
Special Colloquium
Prof. Dr. Bernd Klein
ORATED
MPIfR
Obwohl bis zum heutigen Tage mehr als 1500 Radio-Pulsare in unserer
Galaxie entdeckt wurden, konnte bislang nicht ein einziger Pulsar im
direkten Umfeld des Galaktischen Zentrums gefunden werden. Dies ist um
so mehr erstaunlich, da die statistische Pulsar-Verteilung nicht nur
eine deutliche Zunahme der Pulsare zum Zentrum unserer Galaxie zeigt,
sondern dieser Himmelsbereich auch schon mehrfach in verschiedenen
Pulsar- Suchen intensiv beobachtet wurde. Das Defizit von Pulsaren im
Galaktischen Zentrum wird heute allgemein durch Selektionseffekte bei
der Suche erklärt, die aufgrund von Inhomogenitäten und der erhöhten
Dichte des Interstellaren Mediums im Zentrumsbereich hervorgerufen
werden. Diese Einflüsse bewirken eine frequenzabhängige
Phasenverschiebung (Dispersion) sowie eine Pulsverbreiterung durch
Mehrwegeausbreitung (Scattering) der zeitvarianten Strahlung von
Pulsaren. Während die Dispersion durch geeignete Massnahmen bei der
Beobachtung nahezu vollständig beseitigt werden kann, ist die
Pulsverbreiterung durch Scattering, die einen negativen Einfluss auf die
Suchempfindlichkeit hat, nur mit Beobachtungen bei höheren Frequenzen zu
mindern. Weil die Strahlung von Pulsaren jedoch zu höheren Frequenzen
steil abfällt, kann die optimale Beobachtungs- frequenz nur ein
Kompromiss der beiden gegensätzlichen Forderungen sein. Der Vortrag
berichtet ueber die erste Suche nach Zentrumspulsaren bei der für
Pulsar-Beobachtungen ungewöhnlich hohen Frequenz von 5 GHz mit dem
100-Meter Radioteleskop und analysiert die Ergebnisse vor dem Hintergund
theoretischer Überlegungen über die Detektierbarkeit von Pulsaren im
Galaktischen Zentrum.
Star Clusters as Probes of Galaxy Evolution
Main Colloquium
Dr. Soeren Larsen
ORATED
ADDRESS: ESO, Garching
The last decade has seen an explosion in our knowledge of extragalactic
star clusters. Observationally, major progress has been made on two
fronts: First, HST and large ground-based telescopes have made it
possible to routinely obtain imaging and spectroscopy for globular
clusters (GCs) in galaxies well beyond the Virgo galaxy cluster. We now
know that most extragalactic GCs are broadly similar to those in the
Milky Way: they are mostly old (>10 Gyr), and GC systems often display
bimodal metallicity distributions. Secondly, young luminous “super” star
clusters have been detected in large numbers in starburst and merger
galaxies, but also in some apparently undisturbed spiral galaxies. These
clusters have properties which make them look similar to young versions
of the ancient globulars in our own and most other galaxies. I will
discuss what the study of extragalactic star clusters may tell us about
the evolution of their parent galaxies, and in particular point to a few
pitfalls to watch out for when using GCs to constrain galaxy evolution
scenarios.
The Submillimeter Sky seen through SHARC's eyes
Special Colloquium
Attila Kovacs
ORATED
Caltech, Pasadena, USA
Dust emission is a simple and robust tracer of a galaxy’s gas content,
and star formation activity – in principle, that is. In practice, the
interpretation of dust data is often tricky, especially if it relies
entirely on data from past and present infrared satellites. This is no
small problem as it ultimately limits how well we can understand the
ever growing infrared galaxy populations churned out by these space
missions. Submillimeter data can refine the picture substantially. It
debunks some common myths about infrared galaxies, and perhaps provide
new insights also. I will present data on a few select populations,
ranging from the garden-variety infrared galaxy to hyper-luminous
monsters, and spanning the universe from out local neighbourhood out to
high redshifts.
Applications of Astrochemistry
Main Colloquium
Prof. Tom Millar
ORATED
University of Manchester, UK
In the last 30 yars molecules of increasing chemical complexity have
been detected in molecular clouds. Many of the 120 or so molecules
detected in space can be used as probes of interstellar physics and give
information on temperature, density, velocity and ionization fraction.
In this talk, I shall introduce the physical and chemical processes
which drive molecule formation and illustrate them with two particular
examples - deuterium fractionation in cold cores and two-dimensional
models of protoplanetary disks.
The need for the smallest & the largest - The brown dwarf's weather
Special Colloquium
Dr. Christiane Helling
ORATED
University of Leiden, NL
Brown dwarfs bridge the physical gap between planets and stars.
Presently, the borders of the theoretical modelling in both areas is
explored to uncover the principle chemical and physical mechanisms
responsible, for example, for the particular metal deficiency of brown
dwarf atmospheres or for an ambiguous spectral classification scheme.
Spectral analysis provides strong hints that the weather-like formation
of dust in the highly convective atmospheric environment of a brown
dwarf’s atmosphere does play a major role in understanding these
objects.
After a short introduction to the object class of brown dwarfs and some
of the present challenges, I will demonstrate the necessity of
adequately modelling microphysical processes like dust formation and
turbulence in the macroscopic environment of a brown dwarf atmosphere. I
will present the results of a model for the microphysics of dust
formation including nucleation, growth/evaporation and drift
(gravitational settling) for typical brown dwarf atmospheres. Here, the
1D large scale atmospheric dust stratification is determined by the
interaction of convective overshoot and gravitational settling. The
small scale dust structures are determined by a multi-dimensional
turbulent fluid field which origins from interacting convective cells.
Remarkably, 2D small scale dust structure will develop into large scale,
cloud- and weather-like features.
Huygens at Titan
Special Colloquium
Dr. Michael K. Bird
ORATED
Radioastronomisches Institut, Universität Bonn
The ESA Huygens Probe entered and descended for nearly 2.5 hours through
the atmosphere of Saturn’s moon Titan on 14 January 2005. Huygens
survived impact on the surface and continued its telemetry broadcast to
the NASA Cassini spacecraft, which flew past Titan at an altitude of
60,000 km, for an additional 1.2 hours. Preliminary results from the six
scientific investigations on Huygens include atmospheric height profiles
of temperature and pressure, new assessments of surface composition, and
particularly spectacular views of the surface under Titan’s veil of
haze, as captured by the Huygens imaging system. A review of the initial
in situ observations, as well as an update on the Doppler Wind
Experiment, which was carried out by an international team directed from
the Radio Astronomy Institute of the University of Bonn, are presented.
The QU Imaging Experiment (QUIET) - a technical update
Special Colloquium
Dr. Todd Gaier
ORATED
Jet Propusion Laboratory, Pasadena, CA, USA
TBA
Protostellar "Baby Booms" in Perseus and Orion
Special Colloquium
Dr. Miriam Rengel
ORATED
Thueringer Landessternwarte Tautenburg
The earliest evolutionary phase of star formation, in which a deeply
embedded protostar is known to exist, is the so-called Class 0 stage.
Because protostars in this phase are difficult to detect, constraining
their physical properties is a challenging task. I will present a study
of the thermal emission from the dust of the circumstellar envelopes of
Class 0 sources in order to investigate the physical structure and
properties of these objects. SCUBA imaging at 450 and 850 mum of the
thermal dust emission of envelopes of Class 0 sources in Perseus and
Orion, a model of the envelope, the implementation of techniques like
the blackbody fitting and the radiative transfer approach, and an
evolutionary model for protostars provide a way to model and to
interpret the structure of Class 0 sources, and to estimate their
physical properties in an evolutionary context. This investigation leads
to a more thorough understanding of the Class 0 stage and hence to a
progress in the study of the determination of the initial conditions of
the star formation process.
Planet-forming disks: Recent results from (sub)millimeter interferometer
and the Spitzer Space Telescope
Main Colloquium
Dr. Michiel Hogerheijde
ORATED
Sterrewacht Leiden, The Netherlands
With the detection of more than 100 planets around other stars we now
know that planetary systems are a common outcome of the star formation
process. However, these detected planetary systems show a large variety
of properties, and one can wonder what processes control the
planet-formation process in the disks that surround newly formed stars.
I will present recent observations from interferometer arrays operating
at millimeter and submillimeter wavelengths, that shed light on the
structure and origin of these protoplanetary disks. I will also show
recent data from the Spitzer Space Telescope that provide additional
clues on the content of these disks. I will conclude with an outlook of
what we hope to learn over the next years when powerful new
observational facilities become available.
Observations of the Polarization of the Cosmic Background with the Cosmic Background Imager
Special Colloquium
Prof. Anthony Readhead
ORATED
California Institute of Technology, Pasadena, CA, U.S.A.
Observations of the polarized cosmic background with the Cosmic
Background Imager reveal the polarized spectrum with high significance,
and show that the phase of the acoustic peaks is shifte by 180 degrees
relative to the peaks in total intensity, as expected on the acoustic
wave theory; thereby providing the first evidence for motion on the
scale of galaxy clusters in the primordial density irregularities.