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Faculty of Physics at the Ludwig-Maximilians-University

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Fields of research for PhD projects


 

Extragalactic Astronomy and Cosmology
The USM-MPE extragalactic research group is a joint effort of the University Observatory of Munich (USM) and the Max-Planck Institute for Extraterrestical Physics. The group is located both at the USM (see `Extragalactic Astronomy') and at MPE ). Senior group members are Prof. R. Bender, Prof. J. Weller, Prof. O. Gerhard, Dr. U. Hopp, P.D. R.P. Saglia, Dr. S. Seitz.

The research of the group focusses on dark energy and dark matter in the Universe, on local and distant galaxies, and planets. The aims of our current science projects are:

  • to constrain the nature of dark matter, by searching for MACHOS with pixellensing towards M31, and by analysing cluster and galaxy dark matter halo profiles with strong and weak lensing in combination with dynamical and photometric information for nearby galaxies;
  • to derive constraints on the nature of dark energy, by measuring the power spectra of galaxies and clusters of galaxies at various redshifts, the number density of clusters as a function of mass and redshift, and the redshift dependence of the gravitational lens effect;
  • to understand the structure and dynamics of local and distant galaxies, their stellar populations, their formation and evolution;
  • to build a model of the Milky Way which can be used as a template for galaxy formation;
  • to quantify the role of black holes and dark matter in galaxies;
  • to search for extrasolar planets using the transit method in wide field surveys and understand their properties (mass, density, atmosphere).
We pursue these science questions with a combination of optical and near-infrared observations, theory, numerical modelling, and data interpretation. The group is one of the principal partners in the Pan-STARRS survey which images 3/4 of the sky with unprecedented depth. It is also an important partner in several large international collaborations (e.g., the NUKER team, the PN.S project).

The observational data necessary for our scientific programs come from running own telescope (Wendelstein), partnership in the Hobby-Eberly-Telescope and
Pan-STARRS, SDSS-III-BOSS and DES projects, from guaranteed time received for providing instruments to ESO ( FORS , SPIFFI , OmegaCAM , KMOS), and from participation in public surveys (KIDS, expected to start in 2011).
Furthermore we are members of the CLASH 524-orbit-HST-Multi-Cycle Treasury Program team and the ESO VLT-large spectroscpy program on CLASH-clusters.
Last but not least, we obtain time from applications to the ESO telescopes and the german-spanish Calar-Alto Observatory. In addition we use our Wendelstein observatory in the Alps for pixellensing and other monitoring projects. We expect first light for the new 2m telescope on the Wendelstein observatory in 2011. The instrumentation for this telescopes is partly finished (optical imaging camera, optical IFU spectrograph), further instruments are built.

The numerical modelling uses state-of-the-art numerical methods run on PC clusters. Some of these methods are developed or implemented within our group for specific projects. Recent examples are Schwarzschild's orbit superposition method used for measuring black hole masses, and the NMAGIC adaptive N-body code for modelling galaxy dynamics.

In addition, the USM-MPE extragalactic research group is designing and building imaging and spectroscopy instruments for 1-10m class telescopes, together with national and international partners. We built, e.g., the FORS instruments for the VLT, and LRS (Low Resolution Spectrograph) for the 10m Hobby-Eberly-Telescope in Texas (which we share with the Universities of Texas, Penn State University, Standford and Göttingen). We currently wait for our newly built 1-square degree imager OmegaCam to start operations on the 2.6m VLT-survey telescope (VST) in Chile. Right now we are in the final phase of building the multi-IFU-infrared spectrograph (KMOS@VLT), which is planned to become operational in 2011. In addition we are partners of an international consortium building a giant optical IFU spectrograph (VIRUS@HET).

Finally, we also develop data reduction and analysis software. We are member of ASTROWISE, a european team (USM, Paris, Groeningen, Leiden and Naples) providing data analysis software for the OmegaCAM and any wide field data. This software is essential for all wide field imaging surveys carried out within the ESO community in the future. For the VIRUS project we are developing the pipeline for the automatic reduction of the integral field spectra. We are also members of the EUCLID-satellite team. Our focus here is the design of the optics and combining EUCLID data with ground based data.

We offer PhD projects within our group in any of the above science areas and in instrumentation as well.

Some examples of PhD Projects:

  • Dynamical modelling of galaxies, dark matter and black holes
  • Imprints of Dark Energy in Galaxy Powerspectra
  • Weak lensing and photometric cluster search
  • Weak and strong lensing by galaxies and clusters of galaxies using HST, Panstarrs and DES data
  • Photometric cluster identification
  • Photomeric properties of galaxies (galaxy evolution, based on photometric redshift data)
  • Stellar content and structure of the Milky Way
  • New instruments.
  • Distinguishing models of cosmic acceleration with galaxy clusters with application to realistic cluster data sets.
  • Relastic modelling of modified gravity theories of cosmic acceleration.
  • The nonlinear power spectrum in non-standard models of cosmic acceleration.

For more details see this page.

Our homepages provide detailed information on currently available PhD projects. See, e.g. the weblinks OPINAS and PhD projects.

     
 
 

Difference image movie of a 30 x 30 arcsec2 area in the bulge of M31 from our WECAPP pixellensing project. Long period variables and other variable stars show up as varying black and white spots. Towards the end of the movie a microlens event is visible in the center of the field.

 

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Structure Formation and Cosmology
The research group on Cosmology and Structure Formation is pursuing studies in cosmology and the formation and evolution of large scale structures in the universe. Our work is at the interface of observation and theory, where we seek to bring together new observational constraints with state of the art hydrodynamical simulations of structure formation. We are pursuing cosmological topics such as the nature of the cosmic acceleration and the characteristics of the initial density perturbations. Our ongoing structure formation studies focus on the properties and evolution of the large scale structure, including clusters of galaxies, the most massive collapsed structures in the universe. Senior group members are Prof. J. Mohr, Dr. G. Bazin.

Opportunities exist for those who might be interested in the South Pole Telescope Sunyaev-Zel'dovich Effect survey for galaxy clusters. Here in Munich we are centrally involved in the optical and X-ray followup of these systems, which are very cleanly selected, high mass systems extending to redshifts z>1. These are truly unique and rare systems and are therefore well suited for cosmology if we can successfully characterize their masses using weak lensing, velocity dispersions and X-ray observations. The SPT sample contains about 280 systems presently and will end with approximately 500 massive clusters with accurate individual cluster mass estimates, providing an unparalleled sample for studies of cosmology, non-Gaussianity and the evolution of large scale structure.

There are also opportunities to become involved in the Dark Energy Survey, which is a 5000 deg2, deep multiband optical survey of the southern sky that will begin in Fall 2011. Our group is focused on cluster science, large scale structure and weak lensing studies. In addition, we are involved in the development of the data management system for processing, calibrating and archiving these data. This familiarity with the data gives members of our group advantages in pursuing any analyses that push the data to their limits.

We are working to develop the science case and novel analysis techniques for the eROSITA all sky X-ray survey (PI Dr. Peter Predehl, MPE). This survey will begin in 2013 and will deliver a sample of 105 galaxy clusters and 106 AGN that, in combination with the multi-wavelength optical surveys like the Dark Energy Survey and Pan-STARRS1, should provide the ideal sample for cosmological studies using galaxy clusters and for structure formation and evolution studies using both clusters and AGN.

Finally, there are opportunities to get involved with hydrodynamical simulations of large scale structure. Our group, in collaboration with Dr. Klaus Dolag at USM, is also focused on delivering a next generation hydrodynamical simulation that will reach a volume of 1 cubic gigaparsec with sufficient resolution to follow the formation and evolution of galaxies. These simulations will be central to a wide range of forefront studies, and we expect to pursue some of these studies in combination with data from SPT, DES and eROSITA.

We offer PhD projects within our group in any of the above science areas.

Some examples of PhD Projects:

  • The evolution and nature of density fluctuations out to redshifts
    beyond z=1 using the SPT cluster sample.
  • Clustering and evolution of galaxies using large photometric
    redshift samples from the DES and spectroscopic extensions
    of these surveys that will deliver large samples of spec-z's.
  • Evolution of the galaxy population and the intracluster medium
    within massive clusters from the time of the formation of the
    first such systems to the present.
  • The underlying causes of the cosmic acceleration using techniques
    that include the evolution of galaxy cluster populations and the
    clustering of both galaxy clusters and galaxies.
  • Development of novel algorithms for the improved processing and
    calibration of photometric and spectroscopic optical data.
  Galaxy clusters contain dark matter and baryons in the form of stars, galaxies and a diffuse high temperature X-ray emitting plasma.
 
 

Galaxy clusters are the most massive collapsed structures in the universe, and when they form all material in their vicinity is dragged in.

The mix of baryonic and dark matter in clusters reflects the mix in the Universe as a whole, allowing us to measure the dark matter density of the Universe.

 

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Computational Astrophysics
The research of the computational astrophysics group at the USM is focussed on dynamical processes in galaxies, related to galaxy formation and evolution, the evolution of the interstellar medium and star and planet formation. Senior group members are Prof. A. Burkert, Dr. K. Dolag.

Using different numerical methods and codes, coupled with special hardware connected to local PC clusters for fast computations we explore the complex non-linear evolution of gas in galaxies and its condensation into dense molecular clouds and stars. We explore the collapse of protostellar clumps and cores, the formation of protostellar disks and their condensation into planets. On larger scales we investigate galaxy-galaxy interactions including dark matter, stars and gas and study the morphological transitions of galaxies and the origin of their spheroidal components.

PhD Projects in this group available on

  • Origin of very old, massive elliptical galaxies.
  • The cosmological angular momentum problem.
  • The origin of turbulence in the interstellar medium.
  • Formation of clumpy, turbulent molecular clouds.
  • Formation of stellar clusters and disruption of molecular clouds.
  • Origin and evolution of stellar disks around massive black holes
    in the centers of galaxies.
  • Evolution of protoplanetary disks and their condensation into
    brown dwarfs and massive planets.

     

    A model for the Antennae Galaxies.

More infos are available at www.usm.uni-muenchen.de/CAST/
 

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Expanding Atmospheres of Hot Stars, Gaseous Nebulae, and Planetary Atmospheres
Hot Stars cover sub-groups of objects in different parts of the HR diagram and at different evolutionary stages. The most important sub-groups are massive O/B Stars, Central Stars of Planetary Nebulae, and Supernovae. All these objects have in common that they are characterized by high radiation energy densities and expanding atmospheres. Due to these properties, the state of the outermost parts of these objects is characterized by non-equilibrium thermodynamics and radiation hydrodynamics.

The USM Hot Star group is experienced in the corresponding theory, especially of radiative transfer (1d and 3d) and of stellar atmospheres, and accordingly  in model simulations and the computation of realistic synthetic spectra for these astrophysically important objects. Senior group members are Prof. A.W.A. Pauldrach, P.D. J. Puls, P.D. K. Butler, Dr. A. Kutepov.

Specific topics address the relevance of Hot Stars for current astronomical research:

  • The present cosmological question of the reionization of the universe requires quantitative predictions about the influence of very massive, extremely metal-poor Population III stars on their galactic and intergalactic environment. The objective is to deduce the ionization efficiency of a Top-heavy IMF via realistic spectral energy distributions of these very massive stars.
  • Due to the impact of massive stars on their environment the underlying physics for the spectral appearance of starburst galaxies are rooted in the atmospheric expansion of massive O stars which dominate the UV wavelength range in star-forming galaxies. Therefore, the UV-spectral features of massive O stars can be used as tracers of age and chemical composition of starburst galaxies even at high redshift
  • Distant SNe Ia appear fainter than standard candles in an empty Friedmann model of the universe. This surprising result requires investigating the role of Supernovae of Type Ia as distance indicators with respect to diagnostic issues of their spectra

PhD Projects in this group available on

  • Diagnostics of UV and optical spectra of O type stars
  • Synthetic spectra of the x-ray range of O type stars
  • Synthetic spectra for SN Ia at late phases
  • IR-spectroscopy of massive stars
  • Clumping in hot star winds - constraints from a multi-wavelength analysis

The main focus of the working group thus is to develop diagnostic techniques in order to extract the complete physical stellar information from the spectra at all wavelength ranges.

 
 
Observations

Theory

Applications

Diagnostics

 

IR - Optical - UV - EUV - X-ray wavelengths

 
Left: Eta Carinae.
Below: Calculated and observed UV spectrum for zeta Puppis. The observed spectrum shows the Copernicus and IUE high-resolution observations, and the calculated spectrum represents a state-of-the-art model.
 

More details about the USM Hot Star group and further information on the projects can be found here: http://www.usm.uni-muenchen.de/people/adi/wind.html.

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Plasma-Astrophysics
The Plasma-Physic group at the USM is involved in the research of the macroscopic dynamics of astrophysical plasmas. Senior group member is Prof. H. Lesch.

99% of the visible Universe is in the plasma state. Thus, the understanding of the dynamics of cosmic multi-particle systems under the influence of electromagnetic forces, is of outstanding importance.

Phenomena of special interest to our group are:

  • High-energy particle acceleration processes in the context of (proto)-stellar flares, pulsars, extragalactic jets and cosmic rays,
  • Plasma heating in, e.g., (proto)stellar coronae, galactic high-velocity clouds and the interstellar medium,
  • The generation, reconfiguration, filamentation and energy conversion of magnetic fields in (proto)galaxies, accretion disks, active galactic nuclei.

Our analytical and numerical investigations are carried out on the grounds of the (multi)fluid- as well as the kinetic plasma theory.

PhD issue:

  • TeV Emission from Active Galactic Nuclei
In the Centaurus A x-ray jet high-energy particles are continuously accelerated on kpc length scales up to Lorentz factors of some 107.

More details about the USM Plasma-Physics group can be found at:
www.usm.uni-muenchen.de/people/lesch/deumas.html
 

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Young Stars and Star Formation
The Young Stars & Star Formation group at the USM is involved in the research of individual young stars and whole star forming regions at optical, infrared, X-ray, and sub-mm wavelengths. Senior group member is Prof. Th. Preibisch.

Topics of special interest to our group are:

  • Infrared Interferometry.
  • X-ray Studies of Young Stars.
  • Stellar Populations and Triggered Star Formation in OB Associations.

PhD projects can be offered in the following fields:

  • Stellar Feedback and Triggered Star Formation in OB Associations:
    The interaction of the strong winds and the ionizing radiation from massive stars can destroy surrounding clouds, but, in the right circumstances, it can also trigger secondary star formation by compressing the clouds and driving them into collapse. The group is actively involved in an international cooperation that performs a comprehensive multi-wavelength study of the massive young clusters in the Carina Nebula. Deep surveys in the X-ray, near-infrared, and sub-mm bands are currently performed. One possible PhD project would be to contribute to the analysis and interpretation of these new data.
  • Infrared Interferometry of Young Stars:
    Infrared Long-Baseline Interferometers such as the ESO Very Large Telescope Interferometer can provide very high angular resolution of down to the milli-arcsecond scale. This allows, for the first time, to study the inner circumstellar regions of young stellar objects with spatial resolution below 1 AU and provides new and unique insight into the structure of protoplanetary disks, accretion and outflow processes, and on the multiplicity of the young stars.
 
The image summarizes results on the multiplicity of the Orion Trapezium stars revealed by infrared interferometry.

More details about the USM
Young Stars & Star Formation group can be found at: www.usm.uni-muenchen.de/ys/
 

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Last updated October 2010 by A.W.A. Pauldrach uh10107@usm.lmu.de