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deutsche Version

Master’s thesis projects
at the University Observatory

For general questions please contact A. Riffeser (arri@usm.lmu.de).

1. Instrumentation and observational projects

U. Hopp (hopp@usm.lmu.de), C. Gössl (cag@usm.lmu.de), A. Riffeser (arri@usm.lmu.de), F. Grupp (fug@usm.lmu.de), A. Hess (achim@usm.lmu.de), F. Lang-Bardl (flang@usm.lmu.de)

Project 1.1: Development of instrument control systems with Beckhoff SPS for large telescope systems (M. Häuser mhaeuser@usm.lmu.de, A. Hess achim@usm.lmu.de)

Diese Masterarbeit setzt Interesse an elektronischen Steuerungen und Sensorik voraus. Vorkenntnisse in Elektronik (u. U. entsprechende Master- oder Bachelorvorlesungen) und SPS-Technologien im besonderen sind von Vorteil. Im Rahmen des Baus des MICADO-Instruments für das 39-m-EELT-Teleskop in Chile sind diverse Mechanismen und elektronische Steuerungskomponenten zu entwickeln, bauen und zu testen. Mechanismen und Sensorik müssen in einem Test-Kroystat (~80 K) an der USM getestet und von Beckhoff-SPS gesteuert werden. Die Arbeit umfasst die Konzipierung, Durchführung und Dokumentation von Tests diverser Hardware bei Raumtemperatur und bei ~80 K in unserem Kryostaten. Ergebnisse müssen aufbereitet werden um im Rahmen des MICADO-Projekts von anderen internationalen Konsortiumspartnern verwendet zu werden. Als Steuerungselektronik werden Beckhoff-SPS eingesetzt. Zusätzlich kann je nach genauem Thema ein rein astrophysikalisches Beobachtungs- und/oder Datenauswertungsprojekt in Zusammenarbeit mit dem Wendelstein-Observatorium absolviert werden.

2. Stars and planets

T. Preibisch (preibisch@usm.lmu.de), J. Puls (uh101aw@usm.lmu.de), A. W. A. Pauldrach (uh10107@usm.lmu.de), T. Hoffmann (hoffmann@usm.lmu.de)

Project 2.1: Multi-wavelength observations of star formation regions (T. 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).

Project 2.2: Model atmospheres and synthetic spectra for Wolf-Rayet stars (J. Puls uh101aw@usm.lmu.de)

The model atmosphere code “Fastwind”, developed by our group, is one of the world’s most widely used codes for calculating the optical/IR spectra from massive stars of spectral type O and B. The project presented here aims at stepwise extending the code so that the spectra of so-called Wolf-Rayet stars can be synthesized. The main difference of the atmospheres of these Wolf-Rayet (WR) stars in comparison to those of “normal” stars is a significantly higher wind density (practically all optical lines are formed mainly in the wind) and a different chemical composition: in most cases, the helium and nitrogen abundances (products of the CNO cycle) are greatly increased, whilst the hydrogen abundance is dramatically reduced (until zero). The work presented here requires a strong interest in the implementation of numerical methods.

Project 2.3: 3-D radiative transfer in stellar winds of hot stars (J. Puls uh101aw@usm.lmu.de)

In recent years, substantial progress in the theoretical description of stellar winds from hot stars has been achieved, particularly with regard to the influence of fast rotation and magnetic fields. These theoretical predictions must now be tested by means of observed spectra, which requires a departure from the spherically-symmetric geometry used in current diagnostic methods. Accounting for future developments and already existing computing resources, a treatment in 3-dimensional Cartesian geometry is beneficial. This master’s project shall enable the spectrum synthesis of wind lines, based on such a geometry and a so-called two-level atom, whilst two different methods (short or long characteristics) shall be compared. The achieved accuracies can be determined, for special cases, by comparison with already existing 1-D spherically symmetric calculations. This project constitutes a first building block for models and spectrum synthesis calculations in three-dimensional expanding atmospheres, and a future coupling with hydrodynamic models.

Project 2.4: Period-luminosity relation of long-period variable stars in M31 (J.Snigula snigula@usm.lmu.de, A. Riffeser arri@usm.lmu.de)

Pulsating variable stars are known to follow a relation between the duration of the pulsation, the period, and their mean luminosity. These so-called period-luminosity relations are one of the central tools to get reliable distances of nearby galaxies. Based on theoretical and observational arguments, there has been a long discussion if these relations depends on galactic properties like, e.g., the metallicity of the parent generation of the pulsating stars. Long-period variable stars have, compared with short-period variable stars like Cepheids or RR-Lyrae, been studied only sparsely. Only in the last years a period-luminosity relation was published based on the OGLE data, for the Magellanic clouds (which are very close by and metal poor). The goal of this Master’s thesis project would be to check the long-period variable stars found in the Pandromeda survey of the metal-rich M31 galaxy, and to build using photometry obtained from publicly available data the period-luminosity relation for these stars. Finally these results should be compared with the published results for the Magellanic clouds.

3. Galaxies

H. Lesch (lesch@usm.lmu.de), R. Saglia (saglia@usm.lmu.de), J. Thomas (jthomas@mpe.mpg.de), OPINAS Group (http://www.mpe.mpg.de/1761897/Master-_und_Doktorarbeiten)

Project 3.1: Dynamical modeling of stellar disks (R. Saglia saglia@usm.lmu.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 project answers to these questions will be tested and implemented.

Project 3.2: Dark Matter in dwarf elliptical galaxies (R. Saglia saglia@usm.lmu.de)

Giant elliptical galaxies are embedded in massive dark matter halos. Not much is known, however, about the dark matter halos of dwarf ellipticals, because their low velocity kinematics are difficult to measure. Thanks to our new high-resolution two-dimensional spectrograph VIRUS-W we were able to obtain high quality spectra for a number of dwarf ellipticals in the Virgo cluster. Goal of the Master’s thesis project is the reduction and analysis of these data, their dynamical modeling and the determination of the dark matter density in these objects.

4. Cosmology, large-scale structure, and gravitational lensing

J. Weller (weller@usm.lmu.de), R. Saglia (saglia@usm.lmu.de), J. Mohr (jmohr@usm.lmu.de), S. Seitz (stella@usm.lmu.de), A. Riffeser (arri@usm.lmu.de), OPINAS Group (http://www.mpe.mpg.de/1761897/Master-_und_Doktorarbeiten)

Project 4.1: Comparing simulated and observed red-sequence clusters (S. Seitz stella@usm.lmu.de, K. Dolag dolag@usm.lmu.de)

The majority of galaxies in clusters are “red” galaxies (S0 or elliptical galaxies), i.e., galaxies with no ongoing star formation. This makes them form a “red sequence” in color-magnitude space. In multi-band photometric surveys (e.g., Dark Energy Survey DES) one sucessfully identifies clusters of galaxies by their red-sequence galaxy population, and estimates the (photometric) redshifts for clusters using the colors of their red galaxies. The number of red galaxies of each cluster is used to define its “richness” (a quantity strongly related to the total mass of the cluster). For many purposes in cosmology one would like to relate the observationally identified “red sequence clusters” to clusters numerically simulated within the framework of structure formation. For example, one would like to know how cluster mass and cluster richness scales, what the scatter is, and how much dark matter is associated with individual red galaxies (as a function of the luminosity and position within the cluster). The goal of this project is to apply the observers’ cluster-finding technique to simulated clusters and to derive a catalog with cluster richness, their red-sequence member galaxies, and dark matter halo masses of individual member galaxies. These findings can then be compared to results from observations or can be used to predict the outcome of ongoing and future observations.

Project 4.2: Cluster mass reconstruction with the weak gravitational lensing effect (S. Seitz stella@usm.lmu.de, T. Varga vargatn@usm.lmu.de)

By their (dark and luminous) matter components clusters of galaxies distort light bundles traversing them. This so called weak gravitational lensing effect alters the shapes of background galaxies and aligns their major axes preferentially tangentially to the foreground clusters centers. One can invert the relevant relations to derive mass maps for galaxy clusters, to measure their projected profiles and “total” masses. We offer projects on this topic, where either data from our own Wendelstein 2-m telescope are taken or where public data, or data from the Dark Energy Survey DES, are used.

Project 4.3: Analyzing the strong lensing effect in HST-clusters (S. Seitz stella@usm.lmu.de, A. Monna amonna@usm.lmu.de)

Towards centers of clusters of galaxies the projected matter density can become large enough that objects in the background of such clusters of galaxies are mapped into multiple images and giant gravitational arcs. The analysis of this so-called strong gravitational lens effect yields the most precise astrophysical mass measurements at cosmological distances. In addition one can constrain the amount of dark matter (i.e., the size of dark matter halos) associated with galaxy cluster members. In this way one can measure the cluster subhalo mass function and the amount of dark matter stripped when galaxies fall into clusters and pass their high density cores.

5. Computational and theoretical astrophysics

A. Burkert (burkert@usm.lmu.de), B. Ercolano (ercolano@usm.lmu.de), K. Dolag (dolag@usm.lmu.de), B. Moster (moster@usm.lmu.de)

Bachelor’s and Master’s thesis projects in the field of computational and theoretical astrophysics can generally be offered from the following areas:

  • Structure of the turbulent interstellar medium (ISM) and the formation of molecular clouds
  • Formation of planets, stars, and stellar clusters
  • Stars and their influence on the surrounding interstellar matter
  • Radiative transfer
  • Formation and evolution of galaxies in a cosmological context (local galaxies to high redshifts, galaxy clusters, cosmic web, black holes, self-regulating star formation)
  • Galactic dynamics
  • Active galactic nuclei (AGN)
  • Origin and nature of the gas cloud G2 near the Galactic center
  • Structure and formation of dark-matter halos
  • Magnetic fields and their role on small to cosmic scales
  • Application and development of simulation software on parallel CPUs and GPUs (graphics processors); our hydrodynamic codes are particle- (SPH/N-body) or grid-based, or based on moving-mesh or meshless methods
  • Software for three-dimensional data visualization

Specific subjects are usually selected from the context of current research projects. More information on ongoing and completed projects can be found on the home page of the CAST group.

Last updated 2017 August 01 16:54 by Webmaster (webmaster@usm.uni-muenchen.de)