Abstract
Understanding why galaxies look the way they do is one of the outstanding problems
of modern cosmology. The prime scientific objective of our proposal is to use
gravitational lensing as a tool to investigate the distribution of matter in galaxies,
particularly the 85% that is dark matter. Lensing is equally sensitive to both luminous
and dark matter and no other technique gives information of comparable usefulness
about underlying properties of distant galaxies. We will try and quantify the radial
distribution of dark matter and its granularity, to compare with the results of our best
N-body simulations. We will find out about the baryonic matter in galaxies by their
effect on the light passing through them from the lensed object. Our measurements
will also give a state-of-the-art determination of the Hubble constant through
measuring time delays and using the knowledge we gain about the lens galaxy mass
distributions. Finally, we will look to the future and investigate how new
infrastructures can be tuned to suit our astrophysical needs.
The team we have put together has the diverse range of skills required to achieve our
scientific objectives, and it has evolved from a successful TMR network (CERES)
and numerous ad hoc collaborations. We bring together top theoretical groups with
the most experienced radio and optical observers of gravitational lenses. Our team
also has vast experience in the training of young researchers. Cosmology and the
study of the high-redshift universe attracts some of the best young minds to science,
and the multi-disciplinary nature of our programme will provide a training
environment in which these minds can be developed to their full potential. We are
operating in a highly competitive area where Europe has traditionally played a leading
role. To maintain, or even enhance that position we need to make the most of the
competitive advantages that the HRM activity provides.
1. The Project
1.1 The Research Topic
Understanding how the Universe evolved from almost complete uniformity to the
present state in which there is a rich assortment of planets, stars, galaxies and clusters
of galaxies is one of the most exciting quests of modern science. It grabs the attention
of the public at large and has a strong positive influence in attracting young people
into the physical sciences. Enormous progress has been made; studies of the Cosmic
Microwave Background (CMB), most recently by WMAP, show the tiny fluctuations
in temperature marking the early density perturbations that must eventually grow into
the present day galaxies and clusters. The power spectrum of these fluctuations is in
remarkable agreement with theoretical predictions. Together with results from Type
Ia supernovae, large-scale structure studies and gravitational lensing, the CMB results
lead to a “consensus” cosmological model in which the Universe is spatially flat and
its behaviour is dominated by Dark Matter (DM) and Dark Energy. However, despite
this remarkable progress on the physics of the early Universe, there are still large gaps
in our understanding of the details of the intermediate steps between initial
fluctuations and evolved structures, particularly galaxies. The formation of galaxies is
driven by dark matter but most of what we know about the properties of galaxies is
deduced from studying light, and not matter, and may thus be heavily biased.
Gravitational lensing, the theme of this proposal, on the other hand, tells us exactly
what we want to know, because it traces the total mass (both dark and luminous).
Historically gravitational lensing has been a very strong field of European research.
The prime scientific objective for ANGLES is to use gravitational lensing as a tool to
understand the distribution of matter in galaxies, particularly the 85% of all matter
that is dark, exploiting the fact that gravitational bending is the same whether the
matter doing the bending is of the familiar baryonic variety or dark matter. No other
technique gives information of comparable quality about the properties of distant
galaxies. The network we are proposing springs from a previous TMR network
(CERES) and the well-established CLASS collaboration. It brings together these and
other groups, all of whom are world-experts on diverse aspects of gravitational
lensing and have a strong interest in the mass distributions and dynamics of galaxies.
The aim is to make a coherent attack on this key area of modern astrophysics. We
make some of the most sophisticated N-body simulations of structure formation in a
dark matter dominated universe. We use theoretical methods, both analytical and
numerical, for the reconstruction of mass distributions from lensing observations. And
we make state-of-the-art radio and optical observations. Both the quality of the
observational input and the tools for theoretical analysis are at a stage when a
coordinated approach is required in order to make the breakthroughs we seek. High
redshift astrophysics is becoming a mature subject where the important problems are
now quite well defined; teams using data from the major infrastructures and the latest
theoretical techniques are increasingly the order of the day, and we need such teams
here in Europe to compete effectively on the world scene. We also look to the future
and include as part of our overall project, design studies aimed at shaping the
technology required to produce a major step forward both in the quantity and quality
of observational data. We want Europe to remain at the forefront of this fundamental
area of science.
The well-defined astrophysical focus, but diverse range of disciplines in the proposed
network, will provide a stimulating environment in which young researchers can
acquire skills in theoretical analysis, numerical techniques, radio and optical image
processing and instrumentation technology. We want to offer them the opportunity,
both to become excellent researchers, and to broaden their experience so that they are
in a better position to contribute to a flourishing European Research Area. It is our
assessment that galaxies and galaxy formation is going to be a major preoccupation of
the world astrophysical community for many years to come and we have no doubt that
the demand for well-trained scientists in this area will continue to be buoyant.
1.2. Project objectives
Our project is centred on using gravitational lensing to learn about the matter
distributions of galaxies ranging in redshifts from near zero to of order unity. Multiple
gravitational images of a distant background object are produced on those rare
occasions when there is almost perfect alignment between an intervening galaxy and
the distant object. Radiation is deflected in the gravitational field of the galaxy usually
resulting in two or four magnified and distorted images of the background object. The
magnifications, distortions and relative positions of the images give unique
information about the distribution of matter in the galaxy doing the lensing. In
addition, the interstellar medium within the lensing galaxy also often leaves its mark
on the radiation that has passed through, telling us about the prevailing conditions in
these lensing galaxies. A further bonus of the lensing process is that the light paths for
the images are not the same. If the background object is variable we can measure a
time delay and hence determine the Hubble constant.
We focus on four main project objectives:
1. Matter distributions in galaxies. Density perturbations in the early Universe
grew through gravitational instability giving rise to the beautiful assortment of
galaxy types we observe today. Modern N-body simulations, assuming a cold
dark matter (CDM) Universe, can be used to predict the evolution of the dark
matter fluctuations and can reproduce the observed large-scale clustering
properties of galaxies. However, predicting the remarkable regularities seen in
the galaxy population is another matter. Locally we see spiral and elliptical
galaxies and the latter lie on the Fundamental Plane in a space defined by
velocity dispersion, surface brightness and effective radius. There is a tight
relation between velocity dispersion and central black hole mass. No accepted
explanations exist for any of these systematics. One problem is that the galaxy
light we observe comes from stars that have condensed in the hidden fabric of
dark matter haloes, but the light does not trace these exactly since the baryonic
matter is strongly interacting. We believe that by using lensing to measure the
properties of the dark matter haloes in a range of galaxies and comparing these
with the predictions of state-of-the-art N-body CDM simulations we can lay a
firm foundation for further studies. We are particularly interested in looking
for evidence of hierarchical sub-structure in the dark matter haloes of galaxies,
a generic prediction of CDM models, for which there is no evidence in visible
light. If lensing reveals the predicted sub-structure, we will have confirmed
validity of a fundamental theoretical framework and provided a firm
observational/theoretical foundation for the next step which is to attempt to
understand the origin of the observed morphologies of galaxies.
There are several interrelated sub-projects that we will undertake, each of
interest in its own right, but all also directed towards our main objective. They
are:

To map lens systems whose images have complex internal structure.
The distortions of the intrinsically complex structures introduced by
lensing depend strongly upon the mass distribution in the lens, and can be
revealed by high-resolution radio maps. Various theoretical modelling
techniques (see below) will be used to deduce the (smooth) radial mass
profiles of the lenses. Additionally evidence will be sought for effects of
any mass substructure of the type predicted by most CDM simulations.
These sub-structures could manifest themselves, for example as images of
radio jets that cannot be transformed into each other by using matrices
derived from mass models with a simple radial dependence. Vital to the
success of this quest is to produce the best possible simulations with a
resolution to predict reliably the sub-structure expected within galaxy DM
haloes. The groups in Cambridge, Potsdam and Shanghai are all leading
exponents of this art. An objective of the proposal is to make the best
simulations and, for the first time, use these to predict the ranges of lensing

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effects such halos would produce. The recent evidence (Jing, 2002, ApJ,
574, 538) indicates that the haloes are triaxial and the observational
consequences of this need to be explored.
To develop new techniques that make optimum use of radio data and
optical pictures. Wucknitz (Potsdam) has developed a much-enhanced
version of the LENSCLEAN algorithm which makes explicit use of the
fact that there are multiple images and simultaneously produces an
optimum map of the lensed images and a reconstruction of the unlensed
object. In an outer loop, different model mass distributions can be tried and
the one that produces the minimum residual visibilities chosen. There are
further enhancements to be made and data on more lens systems to be
collected (see above) and analysed with this technique. Bradač (MPIfR)
has successfully used an alternative method for the same kind of task. One
of the advantages of these new methods is that they produce robust error
estimates. Optical pictures, too, often contain vital information on the mass
distributions. One of our other objectives is to extend some of the
underlying philosophy of LENSCLEAN to optical deconvolution.
To use microlensing to explore the make-up of DM haloes. Galaxies
contain stars (and compact dark objects) that, due to their motions, change
their geometry with time and produce observable, short-timescale,
microlensing effects on already macrolensed images. The astrophysical
importance is that the microlensing light curves contain unique
information about the mass function of the stellar-mass compact objects
doing the lensing and which make up part of the dark halo. In this way the
nature of the dark matter is being probed. It is proving a powerful
technique in our Galaxy. The aim is to obtain radio and optical
microlensing light curves and compare with numerical simulations.
To measure lens galaxy velocity dispersions. The first evidence for dark
matter came from measuring rotation curves and velocity dispersions for
galaxies. Lensing is the only other way to obtain such information. Our
aim is to combine the techniques and use large optical telescopes to obtain
spatially resolved velocity dispersions for lensing galaxies. The
complementary information gained from both techniques will be used to
address open questions about galaxy dynamics.
2. The Hubble Constant. After more than 30 years of promise (Refsdal, 1964),
we believe that lensing is about to prove the method of choice for measuring
the Hubble constant (H0). The lens method is geometrical, depending on wellunderstood physics, somewhat unlike the traditional distance ladder methods.
We emphasise that recently reported values from CMB data from WMAP fold
in many assumptions (e.g. the equation of state for dark energy.) Thus, if we
can make an accurate determination of H0, this will contribute directly to the
determination of other cosmological parameters from CMB and other
methods. Time delays and good mass distributions are required to give H0, and
it is usually knowledge of the latter that is the limiting factor. The coherent
programme outlined above will give us more accurate lens mass distributions
and is therefore essential to the success of this project. We will focus our
attention on a handful of the most suitable systems. The sub-projects in this
area are:



To measure and refine time delays using both radio and optical
monitoring. The VLA and MERLIN will be used for the radio work.
Optical monitoring will be with the NOT and the Liverpool Telescope.
Monitoring also gives microlensing light curves.
To quantify the contributions of random and systematic errors to H 0
error budget.
To refine mass models for time-delay lens systems. Various ANGLES
deconvolution techniques, radio and optical, will be used to extract the
best possible constraints.
3. The Baryonic matter in Galaxies. Cold Dark Matter haloes only manifest
themselves through gravity but the baryonic matter strongly interacts with the
radiation on its way through the lensing galaxy often revealing information
about its Inter-Stellar Medium (ISM) unobtainable in any other way. The
intrinsic properties of the emission from the background object are unknown
but we can look for differences in the images that result from propagation
effects. It is important that these effects are disentangled from microlensing
effects, a subject for which there is ANGLES expertise (Wucknitz et al.,
2003). One of our objectives is to measure the dust extinction curves in lens
galaxies. Knowledge of extinction curves, particularly how they may evolve
with redshift and galaxy type, are vital to the interpretation of galaxy
properties (e.g. the distance indicators like type 1a supernovae.) Radio
emission is also affected as it travels through the lens ISM. We see Faraday
rotations/depolarisations, free-free absorption and multi-path scattering. Also
there are some systems that have radio and molecular absorption lines. The
sub-projects are:



To undertake multi-colour imaging and broadband spectroscopy.
Several systems will be targeted to compare the colours of the images
and deduce extinction curves.
To look for radio propagation effects. Observations over a range of
frequencies will be used to look for differences in image properties
which are the tell-tail signs of scattering, absorption and Faraday
depolarisation. We have the ambition to map the rotation measure
round the B0218+357 Einstein ring to tell us about the magnetic field
configuration in the lensing galaxy.
To use absorption line studies to tell us about the state of neutral,
molecular and ionised gas. Absorption lines can also be used to study
gas kinematics in the lens.
4. Looking to the future. Our ability to perform good science depends on having
the correct infrastructure and instrumentation. An objective for ANGLES is to
invest effort into an optical/infrared spectrograph that will be uniquely suited
to lensing studies. We also want to add to the limited pool of known lens
systems and investigate ways in which future searches might cover a wider
range of parameter space and produce a much bigger yield of lenses. The subprojects are:

To build a spectrograph for the VLT that will cover
simultaneously the wavelength range 300 to 1900 nm. This will be



ideal for extinction studies and to probe the scale of lensing substructure using the method outlined by Moustakas & Metcalf (2003,
MNRAS, 339, 607).
To continue optical searches for new lens systems.
To investigate how VLBI methods can be used for lens surveys.
The improved sensitivity of the EVN and the availability of high-speed
computing can be exploited to make new very large lens surveys on
angular scales that have not been probed before. We will make proofof-concept observations.
To plan how ALMA can be best used for lensing studies.
At the completion of the project we expect:
1. To have determined the most accurate value for the Hubble constant.
2. To have shown if there is the expected CDM sub-structure in the dark haloes
of galaxies.
3. To have developed optimised software for the deconvolution of radio and
optical observations of lens systems.
4. To have the best available N-body simulations of structure formation.
5. To have commissioned a versatile spectrograph of novel design for the VLT.
1.3. Scientific Originality of the Project
We live in a flat Universe in which the energy density is divided approximately in the
ratio 1:6:13 between baryonic matter, dark matter and dark energy respectively. It is
believed that the early Universe underwent a period of “inflation” which determined
the properties of the fluctuations that led to the formation of all the structure we see in
the Universe today. That this consensus exists amongst cosmologists is indeed
remarkable progress. But there is no shortage of big questions left to address; what is
the nature of the dark matter, how in detail did the rich variety of galaxies we see
today actually form and, most mysterious of all, what is the nature of dark energy?
ANGLES will concentrate on galaxy formation. Since dark matter and its distribution
is the key to the process and since it (probably) only betrays itself though its
gravitational influence, gravitational lensing is the appropriate tool for its study. In
ANGLES we bring together many of the leading groups working on gravitational
lensing. We think our proposal is particularly timely because we have newly
identified several radio-loud lens systems in which it will be possible to map in fine
detail, using VLBI, the distortions in the lensed images produced by irregularities in
the dark matter distributions on the scales predicted by large-scale structure formation
theories.
The current state-of-the-art is that there are around 80 examples of lensing by galaxies
known. Members of ANGLES have been responsible for the two most successful lens
surveys, one radio (CLASS) and one optical (Hamburg), having found 22 and 12
lenses respectively. To advance the state-of-the-art we will continue with optical
surveys, look for smaller separation (<0.3”) systems through the existing CLASS data
and explore new VLBI techniques designed to make really big surveys in the future.
The astrophysical usefulness of lens systems varies greatly depending on how many
images are present, whether or not the images are point-like and if the redshifts of the
lens and lensed object have been determined. The best have been used for H0
determinations (e.g. Fassnacht et al. 2002, ApJ, 581, 823), have had their radial mass
profiles constrained (e.g. Munoz et al. 2001, ApJ, 558, 657 ) and some have been used
to infer the possible existence of CDM-type sub-structure in the DM haloes of the lens
(e.g. Bradac et al., 2002, A&A, 388, 373). Radio-loud systems are often particularly
useful because it is possible to map with ~1 mas resolution the distortions of the
images introduced by the lens mass distribution. A further example of evidence for
sub-structure is cited by Metcalf (2002, ApJ, 580, 696). In CLASS1152+199 there
appears to be a bend in one jet image in but not in the other, something he thinks is
produced by sub-structure. Though Metcalf uses our CLASS observations, we are not
wholly convinced by the result. One of the prime drivers for ANGLES is to provide
the better quality VLBI observations that are required and more of them.
Complementary to the observations is the theoretical work on N-body simulations of
actual galaxy haloes. We will use the largest sets of simulation data (Jing & Suto,
2002, ApJ, 574, 538) to study the lensing effects of sub-structure and the tri-axilarity
in halo mass distributions. Another way in which the state-of-the-art can be advanced
is to embed a stellar mass distribution in a DM halo and study the lensing effects and
its dynamical properties.
Radial mass profiles are usually quantified in terms of power law models or
sometimes cusp models (Munoz et al, 2002). There are three systems in which the
multiple lines of sight through the lens provided by a complex lensed object have
provided well-constrained mass distributions. In all three the distribution turns out to
be close to isothermal and is not well fitted by the cusp models favoured by numerical
simulations. A surprising result, pointed out by Kochanek (2003, ApJ, 583, 49) is
that, when isothermal models are adopted, for most lens systems with measured time
delays, the resulting values given for H0 are low compared with the value of 728
km/s/Mpc given by the best traditional determination, that from the Hubble Key
Project (Freedman et al., 2002, ApJ. 553, 47). Kochanek suggests that either lens
mass profiles are non-isothermal, or the Hubble key project value is too high. This
makes it clear that there is important work to be done; either radial mass profiles
constrain the Hubble constant, or visa versa. We note that one of the most recent and
robust lens determinations applying LENSCLEAN B0218+357 gives a close-toisothermal profile and a Hubble constant of 784 km/s/Mpc (Wucknitz et al., 2003).
Formally this accuracy already surpasses that of the Hubble Key Project. We know
how to improve our constraints on this object and on others. Apart from the usual
reasons for wanting an accurate value of the Hubble constant we emphasize that all
CMB analyses assume one. If the errors on the assumed value are reduced, then the
accuracy of the other cosmological parameters determined is improved. By measuring
H0 we might even, indirectly, be able to help constrain the equation of state for Dark
Energy!
There are several other radio-loud lens systems suitable for radial profile
determinations since they are known to have images with complicated radio
structures. The highest quality radio observations possible need to be made.
Inferences about the mass models can either be made from the maps using
conventional modelling codes (e.g. Keeton, astro-ph/0102340) or more novel
approaches (e.g. Evans & Witt, 2003, astro-ph/0212013). Very promising are the new
combined modelling and deconvolution methods like LENSCLEAN (Wucknitz, 2003,
submitted to MNRAS). ANGLES will devote the time and effort required to obtain
the best observations of the most promising targets and will continue to lead the way
with the development of mass modelling techniques. The JBO 182 CPU Beowulf
cluster will provide some of the computing power required for deconvolution.
Gravitational lenses are potentially excellent tools for the study of the ISM in the
lensing galaxies; there is always a background object with two or more lines of sight
to it through the lens. Members of the ANGLES team have been responsible for the
determination of two of the three extinction curves determined for galaxies external to
our own (e.g. Motta et al., 2002, ApJ. 574, 719; Wucknitz et al., A&A, in press). Our
proposed programme means that we should be able to improve significantly on the
existing results and extend them to more galaxies. There are reports in the literature of
interesting radio propagation effects such as Faraday rotations, free-free absorption,
multi-path scattering and line absorption, but their potential to give useful
astrophysics has hardly been touched. Four systems are of particular interest,
B0218+357 which shows examples of all the above effects (Biggs et al., 2001,
MNRAS, 322, 821), B0128+437 with four images one of which is heavily affected by
scattering/absorption, B2114+022 in which the effects are so strong that it is not clear
if the system has two or four images and B1830-21 with a lens ISM giving strong
neutral and molecular absorption lines. ANGLES study all these effects, with
emphasis on using absorption in the lens to get kinematic information about the
lensing galaxy.
Particularly for measurements of optical extinction (see above) and for redshift
measurements of lens and lensed objects there is a great advantage in being able to
obtain simultaneous optical and infrared spectra. With current spectrographs this is
not possible. The innovative spectrograph (see Section B1.4.) for the VLT to which
we hope to contribute, will do just what is required. When completed, we intend to
exploit this instrument’s new capabilities to the full.
The original aspects of the project are:
 The use of LENSCLEAN and the development of other algorithms designed
for lens de-convolution and mass modelling and their application to Hubble
constant determinations.
 The first systematic use of VLBI observations to look for evidence of CDM
sub-structure.
 The new ESO VLT optical/infrared spectrograph.
 The exploration of VLBI as the way to make the next generation of radio lens
searches.
 The close coordination between observers and theorists.
1.4. Research Method
To make rapid progress towards achieving the objectives outlined above, we need to
bring a coordinated and multi-disciplinary approach to the subject. We require a range
of theoretical expertise in numerical simulations of structure formation, in both
numerical and analytical lens mass modelling, in techniques of image deconvolution
and in understanding galaxy dynamics. Observationally we need experts in finding
lens systems and in making state-of-the-art radio and optical observations. Having
found lens systems, we need to exploit to the full the observational opportunities to
best address our astrophysical goals.
There is always a symbiosis between observation and theory but often the
theoreticians are not fully aware of what the observers can give them (and how to
interpret the results presented to them by observers) and the observers are often not
sure what the theoreticians really need to test their models. At its simplest level
ANGLES aims to bring some of the leading observers and theoreticians closer
together, so that the optimum use can be made of the available person-power. The
necessity of a closer link between observation and theory is something we wish to
instil in the young researchers who will work in the network. The philosophy in
putting together the network has been to build upon existing collaborations in order to
create a balanced team overall. We include two teams from outside the EU that can
make unique contributions to the network.
The methodological approach is to define a number of tasks each of which will be coordinated by a named individual (or a pair of individuals). The tasks form the
foundations upon which our astrophysical investigations will be built. Projects
focussed directly on obtaining astrophysics from existing data will continue in parallel
with the work on the tasks. The main tasks (and leaders) are:
1. Radio imaging. The task will be to make the best radio images possible of
those lens systems that have extended radio structure in their images. Usually
VLBI observations will be required but sometimes the lower resolution and
greater surface brightness sensitivity of MERLIN (or even the VLA) will be
appropriate. (R.W. Porcas)
2. Optical/IR imaging. The task is to obtain high-resolution optical/IR images
of lens systems with the aims of measuring image flux density ratios, looking
for the effects of dust extinction arising in the lens, to measure the relative
positions of lens and lensed images for model constraints and determine the
optical luminosity and colours of the lens galaxy. This will complement
existing, and perhaps new, HST data. The telescopes of choice are the NOT
and, for the fainter systems, Keck, Gemini or VLT for southern systems. (J.
Hjorth)
3. HST imaging. For some applications HST is a necessity. We have been
awarded 36 orbits of ACS I-band observations to measure the positions of the
images of 0218+357 relative to the lens. This is required for mass models,
hence for H 0 . We are obtaining complementary ground-based imaging to
identify, and measure photometric redshifts for, galaxies close to the line of
sight in order to quantify the shear. Part of the task is to analyse the HST and
ground-based data. Additionally, we are part of the CASTLEs cycle 13
proposal (see above) and analysis and interpretation of these data will be part
of the task. (N. Jackson)
4. Deconvolution. Radio and optical data are hard won and deserve to be
processed to make optimum use of the information they contain. Sophisticated
techniques like LENSCLEAN are beginning to do this for radio data. The task
is to apply these techniques to existing data, develop the techniques further
and extend the concepts to optical data. (O. Wucknitz)
5. Optical spectroscopy. Fundamental to virtually all investigations are the
redshifts of the lens and lensed object. There are still a few missing redshifts
to be worked on. The other focus of this task is to obtain velocity dispersions
for lensing galaxies. The combination of kinematic and lensing information is
useful for the study of galaxy dynamics. (C. Fassnacht)
6. The spectrograph of the future. Traditionally spectrographs work over
relatively narrow bands and never have optical and infrared been observed
simultaneously. Particularly when wide coverage is essential for lens systems,
wavelength coverage fragmented in time is a problem. We expect that ESO
will commission a spectrograph for the VLT to be built in Copenhagen, which
will cover the wavelength range 300 to 1900 nm simultaneously. The device
will be particularly good for extinction studies in lensing galaxies. The task
will be to participate in the construction work and to use it for lens studies. (P.
K. Rasmussen)
7. Radio monitoring. The aim of the radio monitoring is to measure time delays
and to look for variability due to microlensing. The VLA is the instrument of
choice for radio monitoring, but MERLIN can obtain longer runs of data. A
prime target will be B0218+357 since it is the best system for H0
determination and is the subject of a multi-pronged campaign. There is a large
MERLIN monitoring dataset primarily looking for microlensing events. Part
of this task will be to complete the analysis of these data. (A.D. Biggs)
8. Optical monitoring. The drivers behind optical monitoring are very similar to
those for radio monitoring. Microlensing applications, however, assume an
increased importance since it is more common than at radio wavelengths and
has already evolved into a powerful tool with which to study the structure of
the lensed AGN, the point being that the degree of lensing depends on the size
of the object being lensed. The NOT has been very successful in past
campaigns and the New Liverpool Robotic Telescope will soon be in
operation and be ideal for this purpose. We will use both and have access to
both. (J. Munoz)
9. VLBI lens searches. There are <100 galaxy-scale lens systems known. In
CLASS ~16,000 sources were observed individually which is near the limit of
that technique. To make an order of magnitude advance, we need to make
simultaneous observations of many radio sources. The sensitivity of the EVN,
combined with new JIVE hardware at the correlator, makes this a realistic
possibility. The high resolution of VLBI will enable us to find significant
numbers of lens systems with separation <0.3”. We will explore possible
modes of operation, initially in simulation mode, and later to make pilot
observations. (M. Garrett)
10. Optical lens searches. Optically bright, lensed QSOs are targets of choice for
monitoring purposes and for optical spectroscopy comparing multiple lines of
sight. A prime source for such objects is the Hamburg/ESO survey for bright
quasars which has already found 12 lenses. Within the next two years, at least
a doubling of that number is expected from an ongoing high-throughput
survey conducted with the Magellan telescope. (L. Wisotzki)
11. Mass modelling. Much of the ANGLES effort is directed at using
observational data to tell us about the matter distribution in galaxies. The task
is to explore the full range of models. Boxiness and diskiness in early-type
galaxies and barredness and spirality in late-type galaxies have not been
properly explored. Such morphological features will have important effects on
the predicted image positions and flux ratios (P. Schneider, W. Evans).
12. N-body simulations. The task is to use the best possible numerical
simulations of DM haloes to predict their lensing effects. Up to now crude,
semi-analytical, approximations have been assumed for the substructure in
DM when comparing expectations with observations. Are these
approximations valid? We will produce an atlas of possible lens image
configurations using the state-of-the-art simulations and see if the observed
lens systems display the expected symptoms. A spin-off of these simulations is
that we will be able to tune any future lens searches we undertake to search
more efficiently for the expected lens configurations and image separations.
(Y.P.Jing)
13. Microlensing simulations. We will make a set of microlensing simulations
(with varying fractions of smoothly distributed matter) for the quadruple
lenses to study if the observed "flux ratio anomaly" can be explained by
microlensing of a compact plus a smooth (dark) matter component. How much
saddle point images are demagnified will be studied, with the goal to
determine the dark matter fraction in galaxies statistically. (J.Wambsganss)
14. Galaxy dynamics. The task is to develop a model of the Milky Way that
predicts the microlensing optical depth to the Bulge and the Magellanic
Clouds, as well as the fractions of exotic microlensing phenomena. This will
require re-analysing some of the events to check their microlensing nature, as
well as building a comprehensive barred model of the inner Milky Way. (W.
Evans, S. Mao)
1.5 The Work plan
The main project objectives have been presented in Section B1.2 and the tasks are
listed above in Section B1.4. The division into tasks may make the project look
fragmented but the high degree of integration is illustrated in the following charts.
The relationship between the objectives and the tasks is shown in Figure 1. Most of
the tasks involve effort from several different groups (a group being those researchers
based at a single node). The relationship between tasks and groups is shown in Figure
2. An astrophysical-based overview of the project can be gained from examination of
Figure 3. The projected time-lines are shown in Figure 4.
Assuming the proposal is successful, detailed planning work will start at a meeting of
the major players in the network, including group PIs and team leaders. This meeting
would be held before the formal start of the network and at it the work plan would be
consolidated and details, like the exact composition of the task teams and their remits,
fleshed out. The first six months of the network will include the majority of
recruitment of both early-stage and experienced researchers, following the procedures
outlined in Section B2.3. Training of the recruited early-stage researchers will then be
an ongoing and pivotal matter within the network (Figure 4). Recruitment of
experienced researchers will continue for the remaining six months of the year.
The work undertaken within ANGLES will be focussed on milestones (Figure 4),
many of which coincide with the mid-term evaluation of the network in year 2, and
with the final report on the network in year 4. Construction of the VLT spectrometer,
and hence its existence as a task within ANGLES, is conditional on the EU funding
this project. Some of the Hubble Space Telescope work is conditional on a
(submitted) large observing time proposal being accepted.
We have defined milestones by which the network's progress can be judged. Boxed
numbers in Figure 4 indicate the milestones. In task order, the milestones will be:


1, Recruit and appoint ESRs: we will recruit Early Stage Researchers to fill
all ANGLES positions within the first 6 months of the network, using the
recruitment strategy described in Section B2.3.
2, Recruit and appoint ERs: recruitment of Experienced Researchers to fill
the available ANGLES postdoc positions will occur within the first 12 months
of the network.

3,4,5,6, Network-wide activities: by the end of year 1/month 12, we will have
held an ESR/ER “Getting to know you” meeting, the first annual network
meeting and a specialist workshop (see Section B2.1). The annual meetings
themselves will act as milestones in the network's activities, at which progress
in all spheres of network activity can be assessed.

7, Radio imaging: obtain and reduce global VLBI observations for four
gravitational lens systems with extended lensed images. Any one system
would give us improved smooth mass models, information on substructure and
on radio propagation effects in lens galaxies.

8, Optical/IR imaging: obtain four extinction curves for lens galaxies by the
mid-term point.

9, HST imaging: reduce the HST ACS observations of B0218+357 and
determine a position for the lens galaxy, thereby obtaining an improved
measurement of the Hubble constant. A proposal for further HST
ACS/WFPC/NICMOS observations of 66 other lens systems has been
submitted, and if time is granted then further milestones would be set.

10, Deconvolution: develop a new optimal technique to extract maximum
information from optical images of lens systems (i.e. positions and fluxes of
images and lensing galaxies). Perform deconvolution of 1830-21 and
0218+357.

11,12, Optical spectroscopy: obtain velocity dispersions for four lens
galaxies by mid-term. Further, obtain redshifts in new lens systems discovered
in the Hamburg survey by month 48/year 4.

13, VLT spectrograph: if the VLT spectrograph project is funded, we expect
construction to be completed by the end of year 3 and observations to
commence with the instrument in (month 48/year 4).

14, Radio monitoring: perform the final reduction and publication of the inhand MERLIN Key Project lens monitoring data. Reduce the existing four
epochs of VLBI monitoring data on 1600+434. Monitor known lenses such as
0218+357 with the aim of improving the time-delay measurement (month
48/year 4).

15, Optical monitoring: extract microlensing light curves for four lenses
(month 48/year 4)

16,17, New radio lens searches: complete a design study for future lens
surveys using VLBI techniques (month 36/year 3), and conduct pilot
observations (month 48/year 4).

18, Optical lens searches: complete the Hamburg optical lens search (month
36/year 3).

19, Mass modelling: examine substructure lensing in extended-image
systems. Extract radial mass profiles from lenses with extended images,
including 0218+357 and 1830-21. Investigate the effect of modelling errors in
efforts to measure H0 (month 48/year 4).

20, N-body simulations: produce predictions of cluster arc statistics from
simulations (month 12/year 1). Further, predict CDM halo lensing signatures
(month 36/year 3).

21, Microlensing simulations: perform microlensing simulations to study the
flux ratio anomalies in bright image pairs of quadruple lenses and achieve
quantitative results on the fraction of dark matter in the lens galaxies (month
48/year 4).

22, Galaxy dynamics: build a comprehensive barred model of the Milky Way
(month 48/year 4)
2. TRAINING AND TRANSFER OF KNOWLEDGE
ACTIVITIES
The training of young researchers is – along with pushing forward the frontier of the
astrophysical knowledge -- the highest priority of the proposed network. Although the
field of gravitational lensing is relatively well defined, the actual skills needed in the
different sub-fields are quite diverse. To take one example: for a Hubble constant
determination, VLBI observations, HST imaging, state-of-the-art deconvolution and
mass modelling are all necessary. A prime goal of the network is to facilitate the
transfer to and between the young researchers of skills from more than one
specialisation. The result will be researchers who have a more rounded education than
those who can study only at one site. Specific, network-wide, training initiatives are
outlined below. In addition to these, working within a network will allow early-stage
researchers (consistent with family commitments) to make extended visits to one or
more of the other nodes within the network, in order to get hands-on experience of
complementary techniques. Similarly, experienced researchers (postdocs) will be
encouraged to visit other nodes, primarily to disseminate knowledge, but also to
collaborate directly with the network members there. The necessity to work in multinational and multi-disciplinary teams is becoming a fact of modern research life.
Developing the required team-working skills does not come through working within a
single research organisation.
Research tasks for young researchers:
1. At JBO there will be two students and a postdoc. One student will work on the
accumulation of high-quality VLA, MERLIN and VLBI data (supervisor Browne and
working closely with Porcas at MPIfR). The other student will work mainly on the
analysis of OGLE Galactic microlensing data under the supervision of Mao and in
close collaboration with Evans and the Cambridge postdoc who will be an
experienced microlens expert. The aim will be use the knowledge gained about the
mass function and dynamics of our Galaxy as a starting point for the understanding of
galaxy dynamics in general. The JBO experienced researcher will be appointed for
three years and should have a good knowledge of lens modelling and the techniques
of radio interferometry to be able to assist the student. He.she will help the coordinator with some of the scientific organization tasks.
2. At the MPIfR node there will be a student and a postdoc for two years. The student
will be supervised by Porcas and the project will focus primarily on high frequency
VLBI including astrometry and polarization. (The JBO student doing VLBI will work
at lower frequencies and concentrate on mapping low surface brightness structure).
The function of the postdoc will be to explore novel ways of using the VLBI data for
mass model constraints.
3. At Cambridge there will be a postdoc for two years. He/she will play a major role
in coordinating research effort between JBO and Cambridge. He/she should have
experience in microlensing and/or galaxy modelling and will be engaged in
interpreting observational data and building models for both strong lensing and
microlensing. He/she will pay regular visits to JBO and Cambridge will host regular
month long visits from the JBO students.
4. At UKBH.NBI there will be one student. The first part of the student project will
be to contribute to the work on the ESO spectrograph and then to exploit it for
observations. Before the spectrograph is completed it is anticipated that the student
will work on optical/infrared imaging of lens systems to extract extinction curves and
to make preparations for studying some of these systems with the VLT spectrograph
and possibly think about the first ALMA lens observations.
5. At the JIVE node there will be a student who will work on radio propagation
effects and a postdoc for two years who will work on VLBI imaging and future VLBI
surveys.
6. At the Potsdam node there will be a student and a postdoc for two years. The
student will on new de-convolution methods for optical data and the postdoc on
microlensing simulations.
7. At the Spanish node (UVEG) there will be a student and a postdoc for 2 years. The
PhD project for the student will be based on the topic "Lens Monitoring" and focused
on time delay determinations and microlensing studies. The student will be supervised
by Jose A. Munoz with the collaboration of Evencio Mediavilla at the IAC for the
observational tasks (we plan to use the NOT and the Liverpool telescopes) and Luis
Goicoechea at the Universidad de Cantabria for microlensing theory support. The
postdoc will be assigned to the UVEG to work with Jose A. Munoz on mass
modelling of gravitational lenses.
The institutions and local research teams involved in ANGLES are world class, or
even world leaders, in their respective fields of gravitational lens research. The
personnel are very experienced at training young researchers. (As an example, two of
the lecture series at the prestigious 33rd Saas-Fee Lectures this year are among the
proposers of this network, namely from MPIfR and Potsdam.) The resources needed
for doing excellent research are diverse. Observers need access to telescopes and win
observing time. The continuous success of the ANGLES observers in getting
observing on the world’s premier telescopes in the world (HST, VLT, MERLIN,
VLA, EVN, VLBA, Keck VLTI) is the best guarantee that sufficient resources for the
training of the researchers will be forthcoming. The research infrastructure needed for
the more theoretically oriented groups is mainly access to fast computers. In this area
the ANGLES is at present well-resourced. More details of specific resources and the
experience of the individual network teams are given in Section B3.1.
A small unit consisting of an academic (supervisor), an experienced researcher and
one or two students is one of the most effective yet devised for both research and
knowledge transfer. The mixture of early-stage and experienced researchers has been
chosen with this approach to training firmly in mind, while taking into account the
particular needs of the research programme. Many of the ANGLES research goals can
easily be broken into PhD thesis projects (see above). On the other hand, experienced
researchers are needed to undertake some of the more complex tasks. These
experienced researchers will be located at, or near to, the same institute as an early
stage researcher. Early-stage researchers will make up approximately two thirds of the
requested person-power
Each researcher will have a senior scientist as a supervisor/advisor. A Career
Development Plan will be agreed between the researcher and the advisor within
approximately two months of taking up the position. In order to be actively involved
in drawing up the plan it is important that the researcher has a good overview of the
whole of the network activities and research programme before this happens. We are
proposing two specific measures to ensure this (see Section B2.3): the first is to invite
a short-list of candidates to an initial informal network workshop as an integral part of
the recruitment process, the second is for the young researchers collectively, as soon
as possible after appointment as possible, to attend a self-organized meeting of their
own (see below). The Career Development Plan will be updated annually and
collected centrally by the coordinator at the time of the compilation of the network
Annual Report.
We plan a number of measures in order to make sure the training and networking
goals are met:
1. It is essential that a good working relationship between all concerned be
established early in the life of the network, particularly between the young
researchers. To facilitate this, soon after most of the appointments are complete,
the researchers will be asked to organize for themselves a few-day meeting where
the prime purpose will be to get to know each other and discuss their respective
roles in the network. They will be required to produce a report on their activities.
This innovation worked successfully for CERES.
2. Introductory courses and tutorials in the network will be offered in the first two
years and will, where possible, be organized in association with our regular
network meetings. (These will be in addition to the regular courses run as part of
the standard PhD training programmes of the main institutes.) Each course will
last about week and we expect them to be attended by all early-stage and
experienced researchers. The latter, as part of their training, will be expected give
some of the tutorials in their respective fields of expertise. We have in mind:







Using
MERLIN/EVN/VLBI for gravitational
(MPIfR/JIVE)
How to measure the Hubble constant – a case study
(JBO)
Lens mass modelling
(MPIfR/Potsdam/Cambridge)
Microlensing
(Potsdam)
Optical
imaging/spectroscopy
of
lens
(UKBH.NBI/UVEG/Davis)
Galaxy formation and dynamics
(JBO/Cambridge)
N-body simulations
(Shanghai/Cambridge)
lens
work.
systems
3. We will hold annual network meetings to deal with administrative matters, plan
the science and to present our scientific results. All researchers employed by the
network will be expected to give talks on their results. Before such meeting a
special one-day session will be held with the early-stage researchers where they
will rehearse their meeting contributions in front of a small subset of more senior
network members. The talks will be then discussed in content and in form.
Detailed feedback will be given on how to improve the presentations.
4. In addition to the full network meetings, specialist workshops will be held, as and
when they are adjudged to be timely. We anticipate holding a total of three or four
and the experienced researchers will be expected to play an active role in the
organization.
5. Participants of the ANGLES network, especially the trainees, will encouraged to
participate in all national or international conferences of relevance.
6. Where possible, the conduct of specific projects will delegated to the groups doing
the work. Hence some of these management duties associated with individual
tasks can be delegated to the experienced researchers, and occasionally to the
early-stage researchers, so that they may gain experience in complementary skills,
likeproject management
The network will set-up a web page (at the moment, the site www.ANGLES.org is
still available) where all the relevant science results will be displayed to the world.
There will also be internal space for exchange of information and data within the
network before it is ready to disseminate to the community at large. The site will have
an archive of presentations produced for some of the introductory courses and
tutorials. We will also include more general and popular material. There is already a
lot of expertise on popularising our science in the group (see, e.g., web site of the
MPIfR group, or Scientific American article on gravitational lensing 11/2001 by
Potsdam PI)
The gender balance in the physical sciences in general is not good. At senior level in
Europe gravitational lensing the balance is certainly poor. In our defence we point out
that overall most of the groups involved in ANGLES have a higher representation of
women than average, albeit at more junior levels. Our respective institutes enforce an
equal opportunities employment policy and we are all committed to their goals. We
recognise the importance of fostering a relaxed non-threatening environment in which
all young researchers, both male and female, will find it easy to develop their
respective abilities.
We anticipate that on average, most of the training for the early-stage scientists will
be individual, i.e. local to the "home" institution, or on specific visits to other network
nodes. Up to 20% will be achieved in network-wide training phases, like the
workshops and introductory course and tutorials, listed above.