University Observatory Munich

Faculty of Physics at the Ludwig-Maximilians-University

Bachelor & Master Theses

at the University Observatory

For general questions please contact S. Seitz (stella@usm.lmu.de).
Some Bachelor projects can also be extended in scope and assigned to two students to carry out the work together.

1. Instrumentation and observational projects

Project 1.1 (Bachelor project): Development and measurement of optical components and detectors for new instruments at the Wendelstein observatory (U. Hopp, hopp@usm.lmu.de, F. Grupp, C. Gössl, F. Lang)

Several new instruments and optical measuring devices are being developed for the new 2 m Wendelstein telescope. Optical components such as filters, glass fibres, lenses and electronic detectors (CCDs) have to be measured and tested. Projects in these areas can be assigned according to the student’s interests. They include lab work in Munich, development of small control scripts, as well as analysis and documentation of the measurements.

Project 1.2 (Bachelor project): Characterization of the coronograph at the Wendelstein observatory (U. Hopp, hopp@usm.lmu.de, F. Grupp)

Analyse and document the properties of the telescope regarding imaging and spectroscopy of the sun in white light, in Hα, as well as in spectral observations. A number of student lab manuals may be drafted in the course of this project.

Project 1.3 (Bachelor project): Literature work relating to astronomic instrument construction (U. Hopp, hopp@usm.lmu.de, F. Grupp)

Documentation of new developments in instrument and telescope construction — including adjustment methods and environmental influence — are often only to be found in poorly available conference proceedings. The task is to critically look at and compile comments spread over many different courses. Current projects focus on SPIE contributions to wind loads of telescopic mounts, the cleaning and coating of telescope and instrumentation mirrors, and methods of mirror adjustment (e.g., Hartmann analysis).

Project 1.4 (Bachelor project): Development of instrument control software (C. Gössl, cag@usm.lmu.de)

Prerequisite for this project is sound knowledge of and interest in programming. The construction of the instrumentation for the 2 m Wendelstein observatory telescope makes the development of sub unit control software necessary. Task: Document the physical approach, the software solution as well as the integration of both in the whole system. Example: Automation of test rigs in the observatory labs or effective organisation of standard star data sets of the 40 cm telescope.

Project 1.5 (Bachelor project): Database supported calibration of Wendelstein observations (C. Gössl, cag@usm.lmu.de, F. Lang, U. Hopp, J. Snigula)

The Wendelstein telescopes are used to compile large data sets of objects which are being continuously checked for variability (globular clusters, the galaxy M33, etc.). The analysis of these data sets include their integration into standard flux calibrations as well as into multi-filter analyses. These analyses — at least in the outer regions of the objects — can be made by comparing the observations made with those of other observatories as documented in the databases. The optical observations of the Sloan Digital Sky Survey, as well as the NIR observations of 2MASS will be taken into account, in order to examine the colours of variable AGB stars more exactly.

Project 1.6 (Bachelor project): Evaluation of data of the “all-sky” Wendelstein archive (A. Riffeser, arri@usm.lmu.de, U. Hopp)

A small camera has been operated continuously since 2006 to document the cloud cover above the observatory. The project focuses on the analysis of existing or new data sets, in order to improve the clear night statistics and to support the evaluation of scientific data sets. Various techniques for the analysis of the all-sky images are to be tested.

2. Stars and planets

Project 2.1 (Bachelor project): Analysis of the correlation of the X-ray luminosity and rotation in young stars (Thomas Preibisch, preibisch@usm.lmu.de)

Existing X-ray luminosity data of stars and literature data of rotation periods for several young star clusters are to be correlated. The correlation of X-ray luminosity and rotation can give insight into dynamo processes forming the basis of the X-ray emission.

Project 2.2 (Bachelor project): Parameter studies on infrared interferometric observations of young stars (Thomas Preibisch, preibisch@usm.lmu.de)

With the aid of analytical and/or numerical models of the brightness distribution of young stars with circumstellar disks, the impact of certain parameters, (e.g., the strength of scattering on dust particles) on the observables of infrared interferometric observations, are to be examined.

Project 2.3 (Bachelor project): Multi-wavelength observations of star formation regions (Thomas Preibisch, preibisch@usm.lmu.de)

Students can carry out investigations as part of an ongoing project, e.g., correlation of object lists in different wavelengths ranges (from X-ray to the sub-mm regime). Draft future student lab.

Project 2.4 (Bachelor project): Synthetic spectra of hot stars — impact of different model atoms (J. Puls, uh101aw@usm.lmu.de)

The physical parameters of hot stars are mainly determined by means of comparison of observed and synthetic spectra. Calculation of the latter is done using model atmosphere codes. An essential part of these simulations is the description of the underlying atomic processes (radiation and collisions) in so-called model atoms. The objective is to quantify the impact of different existing model atoms on synthetic spectra, for a representative hot star model grid.

Project 2.5 (Bachelor project): Correlation of X-ray emission and fundamental parameters of hot stars (T. Hoffmann, hoffmann@usm.lmu.de, A. W. A. Pauldrach)

A possible correlation between the intensity of the X-ray emission and fundamental stellar parameters is to be carried out. This entails the simultaneous comparison of a sample of existing observed X-ray and UV spectra of hot stars with model spectra which will need to be calculated. This analysis will help to better understand the dynamic processes that lead to the production of X-ray radiation in these atmospheres.

Project 2.6 (Bachelor project): Calculation of mass loss rates of extremely massive stars in starburst clusters (A. W. A. Pauldrach, uh10107@usm.lmu.de, T. Hoffmann)

Using an easy to use program, mass loss rates for a model grid of extremely massive stars that arise in starburst clusters through collisions and merging processes is to be calculated. The stars can have masses of up to 3000 solar masses. (See http://www.usm.uni-muenchen.de/people/adi/RevBer/HotStars-OForT-Mod.html). The data obtained are necessary to describe the formation of these objects and to check the possibility of formation of supermassive black holes through further merging processes.

Project 2.7 (Bachelor project): Why are Ia (SN Ia) Supernovae calibratable standard candles? (P. Hultzsch, pjnh@usm.lmu.de, A. W. A. Pauldrach, T. Hoffmann)

A Monte Carlo simulation is used to calculate synthetic light curves for SN Ia with different ⁵⁶Ni masses, to determine their basic properties (Cappellaro et al. 1997). By comparing observed with synthetic light curves (from archives, such as “The Online Supernova Spectrum Archive”, http://suspect.nhn.ou.edu/) the ⁵⁶Ni mass generated during the explosion can be estimated and, together with the Phillips-relation, the absolute brightness of the star and thus the cosmological distance can be determined (Phillips 1993, Mazzali et al. 2001).

Project 2.8 (Bachelor project): Extension of existing UV observations of samples of central stars of planetary nebula with FUSE data (C. Kaschinski, corni@usm.lmu.de, A. W. A. Pauldrach, T. Hoffmann)

The objective is to extend observed UV spectra of a selected sample of central stars of planetary nebula with FUSE (Far Ultraviolet Spectroscopic Explorer) data. Data from the MAST archive (http://archive.stsci.edu/) are to be edited and combined with existing UV spectra. Finally, a comparison of these extended observations with existing calculated synthetic spectra (Pauldrach et al. 2004) should lead to new findings.

Project 2.9 (Bachelor project): Colours and extinction of Galactic stars in the Sloan Digital Sky Survey and the Two Micron All Sky Survey (S. Seitz, stella@usm.lmu.de)

Objective: To characterize the properties of Galactic stars, such as temperatures and metallicities, as a function of brightness and position by means of colour-colour diagrams. The impact of foreground extinction (dust) on the colours should be examined. The data will then be compared with synthetic colour-colour diagrams (from the convolution of stellar spectra with filter functions). The photometric data for the stars are available from the SDSS and 2MASS surveys.

3. Galaxies

Project 3.1 (Bachelor project): The Andromeda (M31) catalogue (A. Riffeser, arri@usm.lmu.de)

Within the scope of large-scale M31-observations (Pan-STARRS) we expect to be able to measure and better classify thousands of previously analyzed and catalogued stars. Existing star catalogues will be collected and evaluated. Details about the brightness in different filters and temporal brightness variations of stars will be put into databases. A general catalogue will make possible the retrieval of data about specific types of stars and their exploitation.

Project 3.2 (Master project): Constraining the mass distribution of elliptical galaxies with the gravitational lens effect using Hubble Space Telescope observations (S. Seitz, stella@usm.lmu.de)

Elliptical galaxies have a sufficiently high surface mass density in their centers to gravitationally lens galaxies behind them into multiple images or Einstein rings. These observations can be used to measure the mass distributions of these galaxies. The SDSS-III survey BOSS and Hubble Space Telescope observations provide us with numerous elliptical galaxies up to redshift z = 0.7 causing such lensing effects. Some the of the most spectacular systems will be studied in this master project. The goal is to find out how the total mass is made up by the baryonic (stellar) component and the dark matter component.

Project 3.3 (Bachelor project): Dark Galaxy halos and their Galaxies (A. Burkert, andi@usm.lmu.de)

Every galaxy is surrounded by halos of dark energy, but what is the typical mass of a dark halo for a spiral galaxy or an elliptic galaxy of a given mass? This project will find and summarize the answers to this question from the latest research and publications on gravitational lens effects and other theoretical models.

Project 3.4 (Bachelor project): Black holes in elliptic Galaxies (A. Burkert, andi@usm.lmu.de)

The probability is high that massive elliptic galaxies contain massive black holes. These can form when two spiral galaxies merge. In this project, high resolution computer simulations of interacting galaxies and the properties of the black hole formation will be analysed. The software for this analysis and the simulations are provided.

Project 3.5 (Bachelor project): The evolution of the Milky Way (A. Burkert, andi@usm.lmu.de)

This project aims to compile the properties of the Galaxy as well as different theories of its evolution from the literature. In addition, numerical methods are provided with the aid of which different evolutionary theories can be tested.

Project 3.6 (Bachelor project): Dynamos in galaxies (Harald Lesch, lesch@usm.lmu.de, Hanna Kotarba)

All galaxies are magnetized. Where do galactic magnetic fields come from, how are they maintained and how are they structured? These are the questions we wish to answer. In this project we will develop a model for the amplification of galactic magnetic fields based on analytic calculations.

Project 3.7 (Bachelor project): Propagation of cosmic rays in the Galaxy (Harald Lesch, lesch@usm.lmu.de, Hanna Kotarba)

Cosmic rays represent a small but high-pressure part of the interstellar medium. Through their pressure on the magnetic fields, cosmic rays contribute considerably to the galactic dynamo. In this project we will analyse the properties of Galactic cosmic rays and their impact on gamma-ray emission.

Project 3.8 (Bachelor project): The age of a galaxy (R. Saglia, saglia@mpe.mpg.de)

How do we measure the age of a galaxy? The bachelor thesis should summarize the methods that have been developed to reach this goal and their uncertainties. If there is enough time, one can also derive a spectroscopic age from data available for a selected number of objects.

Project 3.9 (Bachelor/Master project): Dynamical modeling of stellar disks (R. Saglia, saglia@mpe.mpg.de, J. Thomas, jthomas@mpe.mpg.de)

Three-dimensional galaxies are often modeled using the Schwarzschild approach. One computes stellar orbits in a given gravitational potential and superposes them to reproduce the available dataset. The modeling of two-dimensional objects like galaxies with stellar disks poses some yet unsolved questions. How well can one compute the gravitational potential using spherical harmonics? What is the optimal amount of regularization? How well can one describe real galaxies? During the thesis answers to these questions will be tested and implemented.

Project 3.10 (Bachelor project): The masses of supermassive black holes at the centers of galaxies (R. Saglia, saglia@mpe.mpg.de)

How do we measure the masses of supermassive black holes at the centers of galaxies? What are their uncertainties? How much mass is hidden in supermassive black holes? The results of the recent research should be critically summarized and discussed.

4. Cosmology

Project 4.1 (Bachelor project): Distances to supernovae in various cosmological models (J. Weller, weller@usm.lmu.de)

The student will derive the correlation between distance and red shift for different Friedmann Models. Boundary conditions to cosmological parameters will be derived by comparison with supernova data. These analyses are made with the aid of so-called Monte Carlo Markov chains. If there is enough time, the analysis can be extended to models with extra dimensions.

Project 4.2 (Master project): Constraining the mass distributions of clusters of galaxies with the weak gravitational lens effect (S. Seitz, stella@usm.lmu.de)

Clusters of galaxies are massive structures that cause a gravitational lens effect on galaxies in their background. In the central regions where light deflection is strong multiply imaged galaxies and giant gravitational arcs can be produced. In the outskirts of the clusters the light deflection is weaker, but still measurable, since the shapes of background galaxies are distorted. The measurement of these distortions (weak lensing effect) can be turned into mass estimates for the foreground clusters. We invite students with interest in observations, data analysis and skills in probing theoretical models to join our group. Depending on the preference of the students the project can be more theoretically or observationally oriented. Several students can work simultaneously on these projects. Data for this project are available from ESO telescopes, from surveys like Pan-STARRS and in future also from KIDS and DES and they will also be obtained with our new wide field imager on the just-installed 2-m Fraunhofer telescope on Mount Wendelstein.

Project 4.3 (Master project): Constraining the mass distributions of clusters of galaxies with the strong gravitational lens effect (S. Seitz, stella@usm.lmu.de)

Clusters of galaxies are massive structures that cause a gravitational lens effect on galaxies in their background. In the central regions where light deflection is strong multiply imaged galaxies and giant gravitational arcs can be produced. These multiply imaged galaxies and giant arcs can be used to precisely measure the mass distribution in the center of the clusters of galaxies. The results can be compared with predictions of structure formation. We will study a few clusters of galaxies with superb Hubble Space Telescope Imaging data from the CLASH survey.

Project 4.4 (Master project): Unveiling the nature of dark energy: new methods for measuring the shapes of galaxies (S. Seitz, stella@usm.lmu.de, D. Grün, dgruen@usm.lmu.de)

This project is for students with a high level of creativity, curiosity, theoretical interests and computational skills. The EUCLID satellite project was selected by ESA for the Cosmic Vision program in October 2011. EUCLID aims to find the reason for the accelerated expansion of the universe which might be caused by a so-called dark energy or by a deviation of nature’s laws from general relativity. A major goal of the EUCLID mission will be to measure the universe’s density fluctuations and their growth in time using the gravitational lens effect of the density fluctuations on background galaxies. This effect, called “cosmic shear”, is tiny. Its measurement requires to measure shapes of galaxies extremely precisely and to discover and account for artificial distortions coming from, e.g., the optics of the satellite’s camera or from data processing artefacts. Our group has developed some new ideas on shape measurement methods and we are keen on intensifying this work.

Project 4.5 (Bachelor project): The size evolution of galaxies (R. Saglia, saglia@mpe.mpg.de)

The size of a galaxy changes during its life. Goal of the thesis is to summarize the results of the last years of published research. How do we measure the size of a galaxy? What is the rate of change of the size of a galaxy with time? Does it depend of the mass of the galaxy? What are the mechanisms that drive the size change of galaxies?

5. Numerical Astrophysics

Bachelor- und Masterarbeiten auf dem Gebiet der Numerischen Astrophysik in der CAST-Gruppe sind jederzeit möglich. Speziell auf den Gebieten der Planetenentstehung, Sternentstehung, Galaxienentstehung und der Entstehung von großskaligen Strukturen vergeben wir jederzeit aktuelle Themen auf Anfrage bei A. Burkert (burkert@usm.lmu.de), B. Ercolano (ercolano@usm.lmu.de) und K. Dolag (dolag@usm.lmu.de). Mehr Informationen über aktuelle und abgeschlossene Projekte finden sich auf der Homepage der CAST-Gruppe.