Student Projects





Student projects (Master and PhD) within the framework of numerical astrophysics as carried out by the CAST group (see our research pages) are always available on request.

Please contact
A. Burkert (burkert[at]usm.lmu.de)
B. Ercolano (ercolano[at]usm.lmu.de)
K. Dolag (dolag[at]usm.lmu.de)
for possible projects.

Funding for PhD projects can be obtained by applying to the "International Max Planck Research School on Astrophysics (IMPRS)", the "Cluster of Excellence for Fundamental Physics (Origin and Structure of the Universe)" or the current "DFG Schwerpunktprogramm ISM", or sometimes by 3rd party funding obtained by individual group members.

If you are interested in a Bachelor project, more information and a registration form can be found here.

Currently ongoing PhD projects
The engines of galaxies: towards a better understanding of active galactic nuclei

The engines of galaxies: towards a better understanding of active galactic nuclei

Almost every galaxy hosts a supermassive black hole. This black hole is located in the center of the galaxy and is fueled by in-falling gas, either from the galaxy itself or due to mergers with other galaxies or smaller substructures. Whether gas is accreted or not depends strongly on its properties such as the temperature or angular momentum. Only a fraction of the accreted matter leads to mass growth of the black hole, while the remaining energy is emitted by the black hole (AGN feedback) in the form of radiation and mechanical outflows (jets). In large cosmological simulations the gas properties and different types of AGN feedback are often neglected. To include such effects I develop sub-grid models and use the Magneticum Pathfinder Simulations at first to test the models and then to implement them in larger simulations. These simulations can be useful for making predictions i.e. for scaling relations between black holes and their host galaxies or to understand the clustering of AGN depending on their properties and environment. This can be used i.e. to estimate cluster masses from observables or to calibrate X-ray and SZ observables.
Lisa Steinborn
Origin and Properties of Giant Clumps in z=2 Disk Galaxies

Origin and Properties of Giant Clumps in z=2 Disk Galaxies

High resolution observations of disk galaxies at high-redshift e.g. with ESO's VLT reveal distinct differences when compared to present-day disk galaxies. Their structure is irregular with highly turbulent motions and high gas fractions of 30-80%. Stars form with enormous rates of a factor of 10-100 higher than in the Milky Way. The star formation is concentrated in a few gigantic clumps of molecular gas, about 1000 times larger than present day molecular clouds, and as big as dwarf galaxies. Numerical simulations of gravitationally unstable gas-rich disks show that fragmentation naturally leads to contracting and self-rotating clumps. However clear observational evidence for spinning clumps is still missing, which might either be caused by limited resolution or an alternative formation scenario. In order to gain a better understanding, we run idealized high resolution simulations of isolated gas-rich disks with the adaptive mesh refinement code RAMSES to follow the fragmentation process of gravitational instabilities from the beginning and the evolution up to a few orbital times. We also mock beam smearing effects to compare our results with observations.
Manuel Behrendt

Self-regulated star formation in and evolution of galactic disks, including as infall from the cosmic web

We use hydrodynamical methods to examine the influence the accretion of extragalactic hydrogen has on star formation rates and structure formation in disk galaxies with a spiral density perturbation. We also take into account radiative processes and stellar feedback. Our long term goal is to execute simulations with both maximum physical completeness and unprecedented resolutions.
Max Brunner
Massive Star Feedback

Impact of massive stars on the surrounding medium

The aim of this project is to shed light on the impact of massive stars on the interstellar medium (ISM) in their surroundings. A good example of a region revealing such interactions between stars and the ISM is the Orion/Eridanus Superbubble (OES), a cavity blown by stellar winds and supernova explosions. This region has the advantage of being well observed. Its interaction with the local bubble, the dilute region in the ISM in which our sun is located, makes this zone even more interesting. We have developed a population synthesis code using modern stellar models to calculate the output of mass and energy from groups of massive stars, so-called OB associations. The spread of the ejecta into the ISM is followed with hydrodynamical simulations. The observational constraints on the 26Al distribution provide information on the time scales of the interaction process, since 26Al is a radioactive trace element that decays approximately a million years after being ejected from the stars. Thus, the spread of 26Al in different hydro models will help to understand the peculiar shape (distribution of density, shocks, evolution of star birth regions) of the OES.
Katharina Fierlinger
ESO image of NGC 7252

The Outer Structure of Elliptical Galaxies and their Dark Matter Halos

The outer haloes of elliptical galaxies have been studied by observations of planetary nebulae as tracers for the LOSVD for several years to adress the questions of the nature of the Dark Matter halo they are embedded in and the mechanisms that drive the formation of elliptical galaxies, revealing a huge variety of different profiles, some flattening to nearly constant values, some increasing again in the outer part and some decreasing fastly, showing nearly no evidence of a dark matter halo. We try to explain the nature of the different profiles by studying different evolution scenarios for elliptical galaxies from simulations.
Rhea-Silvia Remus


Finished PhD projects
Massive Star Feedback

Massive star feedback and triggered star formation

Over their lifetime massive stars strongly affect the surrounding cloud. Strong stellar winds and ionizing radiation create HII regions, generate bubbles and pillar-like structures. The compression of material by the wind and the radiation shocks eventually leads to gravitational collapse and subsequent star formation. To study the effects of massive star feedback on the surrounding cloud, we perform numerical simulations using smooth particle hydrodynamics (SPH) and perform a detailed comparison of the results with multi-wavelength observations of the Carina nebula which is the most nearby southern region with an important population of massive stars.
The objectives are:
  • to determine the relative importance of ionizing feedback and stellar winds from high mass stars.
  • to understand the effects of massive star feedback on the star formation process, i.e. to determine whether star formation is inhibited or rather triggered by stellar feedback.
  • to assess the importance of the second generation of stars in comparison to the first one in a star forming region.
Image: A pillar of gas in the Carina Nebula. Radiation and fast winds from the stars sculpt the pillar and cause new star formation within it (Credit: NASA, ESA, and the Hubble SM4 ERO Team).
Judith Ngoumou, 2014
Star Formation near the GC

Simulating Star formation near the Galactic Centre Black Hole

In this work we try to understand the formation of the discs of stars near the Galactic Centre in our Milky Way, as observed by the infrared group at the MPE (Genzel et al. 2003, Paumard et al. 2006, Bartko et al. 2009). For this we simulate the infall of molecular clouds onto the central black hole using the smoothed particle hydrodynamics (SPH) code GADGET2. During the encounter the clouds engulf the black hole in part, leading to gas streaming around the black hole with opposite angular momentum. This gas collides and settles into an eccentric accretion disc around the black hole which eventually becomes unstable and fragments into the observed stellar disc.
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Christian Alig, 2013
Magnetic Fields in Protogalaxies

Magnetic Fields in Protogalaxies

We are studying the amplitude and structure of the magnetic field during formation and evolution of galaxies. Our goal is to get a starting understanding, if and how a magnetic seed field, that might have been created through battery effects in the early times of the universe and is of the scale attogauss, could have evolved and amplified to the microgauss levels one can observe in galaxies today. Additionally we are looking into the effects that the addition of the magnetic energy density has on properties of those systems, like star formation rates and metallicities. Starting at high redshift and including star formation and feedback, we are performing non-radiative simulations with the SPH code Gadget3. We are also working on finding new ways to further develop the cosmological MHD implementation, by studying the effects of different kernels, dissipative terms and error corrections in SPMHD.
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Alexander Beck, 2013
Carina Nebula

Deriving a clump mass function of the Carina Nebula

The Young Stars & Star Formation group (Head: Prof. Thomas Peibisch) is currently involved in a large multi-wavelength project to study the young stellar populations in the Carina Nebula. This site of very recent and ongoing massive star formation allows a detailed look at the interaction of the winds and radiation of the numerous very massive young stars with the surrounding molecular clouds. With near-infrared, X-ray, and sub-mm observations we will investigate how the feedback from the massive stars disperses remnant clouds at some locations and triggers new generations of stars in other locations. I am using sub-mm data which trace the cold dust to derive a clump mass function of the Carina Nebula. Our aims are to investigate the cloud morphology and the effects of massive stellar feedback on the molecular cloud.
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Stephanie Pekruhl
Physics of Galaxy Clusters

Studying the physics of galaxy clusters by simulations and X-ray observations

Clusters of galaxies are optimal targets to study the large--scale structure of the Universe as well as the complex physical processes on the smaller scales. It is therefore vital to unveil cluster intrinsic structure, precisely estimate their total gravitating mass, and accurately calibrate scaling relations between observable quantities. A promising approach to achieve a more detailed picture of such complicated objects is found in the comparison between hydrodynamical numerical simulations of galaxy clusters and X--ray observations.
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Veronica Biffi, 2012
Supernova-driven Wind

Supernova-driven Galactic Winds

Galactic winds are common features within Lyman-alpha emitting galaxies at redshifts z>2. It however remains unclear what mechanisms are responsible to launch this type of outflow. The underlying project is based on hydrodynamic grid simulations with NIRVANA to investigate the conditions for a supernovae-driven galactic wind, and will also include a detailed parameter studies.
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Wolfgang von Glasow, 2012
Survival of Galaxies in Cluster Simulations

Studying the survival of galaxies in hydrodynamical simulations of clusters

The project aims at investigating galaxy cluster formation and evolution by means of numerical simulations performed with a modified version of the TreeSPH code GADGET-3. This new version of the code employs adaptive softening to describe the gravitational interaction between the simulation particles; having this quantity variable in space and time, as opposed to having it fixed at the beginning of the simulation, allows to increase the spatial resolution in overdense regions whilst keeping particle-particle noise under control in less dense environments. Simulations involving gravitational as well as gas dynamics are likely to considerably benefit from the adoption of this scheme: the adaptive behaviour of the resolution scale should allow to follow the collapse of dark matter and particularly gas down to scales which are currently unachievable in standard simulations at comparable mass resolution, thus providing a more reliable representation of the behaviour of galaxy-like substructures.
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Francesca Iannuzzi, 2012
Cold Filament Formation

Formation of cold filaments and interstellar turbulence

I study the formation of cold filaments in the ISM with hydrodynamical simulations of wind-blown superbubbles from OB associations using the RAMSES code. I am also interested in the drivers and properties of interstellar turbulence. The picture shows a zoom-in on one of the formed filaments in the simulation. Axes are in parsecs, shown is logarithm of hydrogen number density.
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Eva Ntormousi, 2012
Nonthermal Emission in Galaxy Clusters

On the non-thermal emission in galaxy clusters

We investigate the transient phenomenon of radio haloes - Mpc sized, diffuse radio sources found exclusively in a fraction of merging galaxy clusters. The non-thermal spectrum suggests that in the intra cluster medium Cosmic Ray electrons interact with magnetic fields to emit Synchrotron radiation. Using the cosmological MHD SPH code Gadget3 we investigate Secondary and, for the first time, Reacceleration models as sources for the short lived cosmic ray electrons.
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Julius Donnert, 2011
Downsizing

Origin of the anti-hierarchical growth of black holes in the universe

In our current picture of galaxy formation, it is commonly accepted that every spheroidal galaxy hosts a supermassive black hole (SMBH) in its center. Moreover, SMBHs are found to be tightly correlated to properties of their host galaxies, as luminosity, bulge mass, velocity dispersion. This suggests a co-evolution of galaxies and black holes. However, detailed physical processes are still not well understood. One puzzling question, which we assess in this study, is to understand the observed downsizing trend in black hole growth. Investigating the number density evolution of AGN, observations show that luminous AGN peak at higher redshifts than less luminous ones (see colored dashed lines and grey shaded areas in the left image), implying that massive black holes form already very early in the universe, whereas less massive objects predominantly seem to form at later times. However, in order to explain the observed downsizing within a hierarchical structure formation model, accretion mechanisms onto the black holes and their corresponding efficiences will be of crucial importance. Thus in order to investigate this problem, we use a semi-analytic model, where we find additional modifications to be important ingredients in order to match the observations. This is illustrated by the solid, colored lines in the panel on the left-hand side showing a reasonably good agreement with the observations.
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Michaela Hirschmann, 2011
Survival of Galaxies in Cluster Simulations

Magnetic field evolution in spiral galaxies

Magnetic fields are believed to be importanant in many astrophysical processes like star formation, cosmic ray confinement and jet formation. However, despite their importance, the origin and evolution of magnetic fields in galaxies is still not well understood. Magnetic field evolution is tightly coupled to galactic evolution. In the standard cold dark matter clustering models, galaxies evolve through several major and minor mergers of galaxies and galactic subunits. Thus, galactic interactions should be a crucial part of magnetic field evolution, which is why we investigate interacting galaxies including magnetic fields using N-body/SPH simulations. Our studies show that magnetic fields are efficiently amplified up to equipartition between magnetic and turbulent pressure during galactic collisions. Moreover, magnetic fields seem to be important for the propagation of shocks in the interstellar medium. Therby, the Mach numbers of the shocks are higher for stronger magnetic fields, suggesting that the shocks are supprted by magnetic pressure. Artificial radio maps of our simulated systems are in good agreement with observations.
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Hanna Kotarba, 2011
SPMHD for Cosmological Simulations

Smoothed particle magneto-hydro-dynamics for cosmological applications

We study novel implementations of MHD in SPH, constraining and understanding the effects of non divergentless magnetic field. We apply this methods in non-radiative cosmological simulations that allow us to study the large scale effects of magnetic fields and we found limits in detectability for current instrumental capabilities.
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Federico Stasyszyn, 2011
KHI and DE

Hydrodynamical Instabilities and the Trace of Dark Energy within the CMB

Part I: The first part concentrates on the numerical description of the Kelvin-Helmholtz instability (KHI), based on the two most widely used approaches, 'Smooth particle Hydrodynamics' (SPH) and grid based codes. Re-derving the analytical linear viscous KHI growth rate we study the evolution in detail and compare the simulated amplitudes with the analytical expectation.
Part II: The second part analyzes the influence of Dark Energy on cosmic structures, which results in non-Gaussian contributions known as secondary anisotropies. In particular, the Rees-Sciama effect (which includes the nonlinear evolution of structures) plays a crucial role. The effect of different DE models, such as quintessence can be studied analytically with the three point correlation function, or the bispectrum.
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Veronika Junk, 2010


Finished Diploma/Master projects

Modelling Warm Dark Matter in Cosmological Simulations

The standard ΛCDM model of cosmology postulates that the formation of structures in the universe is driven by a largely unknown component of dark matter. It is one of the most important projects of modern physics to find out what dark matter is. Cosmological simu- lations are an important tool to predict the effects of different dark matter models, and to constrain properties of dark matter by the comparison with observations of our universe. We attempt to simulate different warm dark matter scenarios in cosmological ”zoom-in” simula- tions (which allow the investigation of a single object in high resolution), and comsological boxes (which exhibit low resolution, but good statistics). However, N-Body simulations of warm dark matter suffer from the artificial fragmentation of filaments into small, spurious halos. We decide to address this problem by considering new numerical approaches. As a first approach we test Adaptive Gravitational Softening, but find that it does not help out, as it does not follow the anisotropic distortions of the dark matter sheet. Therefore, we develop the new numerical technique Anisotropic Softening which is based on the potential of ellipsoids that can deform and rotate along all three axes individually. The deformations of the ellipsoid are defined by the Geodesic Deviation Equation, a numerical technique that follows the dis- tortions of an infinitesimal volume element around each particle (Vogelsberger et al., 2008). With Anisotropic Softening we manage to match mass- and force-resolution precisely also in situations of highly anisotropic collapse, and thereby avoid any artificial fragmentation while keeping the force resolution high. As a last step we present warm dark matter simulations in a full cosmological environment that do not suffer from any fragmentation.
Jens Stücker, 2015

Black Holes in the Magneticum Pathfinder Simulations

Over the last years it has been generally accepted that black holes are essential to understand the formation and evolution of galaxies. But the detailed connection between the growth and evolution of black holes and their host galaxies as well as the observed, fundamental scaling relations between them are currently only poorly understood. In my thesis the Magneticum Pathfinder simulations are analysed quantitatively and qualitatively. Resolving galaxies and AGN feedback in cosmological simulations allows challenging the understanding of galaxy formation and its connection to black hole physics. In my thesis the reliability of the current black hole model is demonstrated by comparing the simulation with observations, i.e. the relation between the black hole mass and the stellar mass, the M-sigma-relation, the stellar mass functions or the luminosity functions at various redshifts. The simulations in general are very successful in reproducing these relations. Thus it is possible to investigate in detail how black holes grow, how their luminosity evolves over cosmic time and what their environment looks like. I could show that galaxy mergers play an important role for the black hole growth and thus for the appearance of AGN, which is depicted in the figure. The red dot represents the black hole, whereas cold gas is blue, hot gas is red and stars are white. The graphs below show the mass growth and the light curve of the black hole. The peak in the luminosity appears during a merger. I also found that fainter AGN can be triggered by mergers or smooth gas accretion. Furthermore I studied AGN feedback and black hole accretion in more detail. Thus the simulation could be improved by implementing a radiative efficiency of the AGN feedback, which depends on the black hole mass. I also showed that we have to improve the accretion model. In the simulations the Bondi model is used. The Bondi accretion rate is multiplied by a boost factor. Since the choice of this factor has a significant effect on the black hole growth we have to further understand the origin of this parameter.
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Lisa Bachmann, 2014

On anisotropic thermal conduction in cluster cooling flows

Observations show that thermal conduction in cooling flows of galaxy clusters is strongly suppressed in some regions. This suppression is due to the restrictive motion of charged particles in a cluster's magnetic field. In this work we derive a numerical scheme to implemented anisotropic thermal conduction in the SPH code GADGET3, enhancing the existing isotropic formulation (Jubelgas et al. 2004). We present several approaches to handle this task and discuss the outcome using test cases as well as cluster simulations.
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Alexander Arth, 2013

The thesis applies modern programming techniques to simulations of star-forming molecular clouds. It is composed of three parts: first, methods to efficiently set up, export, start, and analyze runs of a Smoothed Particle Hydrodynamics (SPH) simulation, using the Espresso simulator. Second, simulations of the radial density distribution of isothermal star-forming filaments using a custom one-dimensional grid simulator with cylindrical symmetry. And third, an assessment of the F# programming language, Common Language Infrastructure (CLI) and the functional programming paradigm in general for use in physical applications.
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Georg Michna, 2013

Self-regulated Star Formation in Galactic Disks, Influenced by the Accretion of Cosmic Gas

Developing and testing numerical methods to examine the appearance of a self-regulated equilibrium state in spiral disk galaxies, where the star formation rate follows the accretion rate of extragalactic gas.
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Max Brunner, 2012
Giant Clumps in High-Redshift Disk Galaxies

Giant Clumps in High-Redshift Disk Galaxies

(i) Developing the required observations and theory. (ii) Setup of stable/unstable gas disks, embedded in a spherical dark matter halo, by using the grid-code RAMSES. (iii) Analyzing of the disk transformation and the developed clumps.
Manuel Behrendt, 2011


Finished Bachelor projects
Turbulence in SPH

Turbulence in SPH

The thesis at hand has been prompted by recent publications about the "natural" limitations of smoothed particle hydrodynamics (SPH) with regard to the simulation of turbulence. These findings center around unwanted side effects of artificial viscosity, which needs to be introduced into the otherwise perfectly Lagrangian scheme to implement dissipation. Most prominent in that regard is the paper by Bauer and Springel (2012) about deficits in the subsonic turbulent regime, which dissuades further use of SPH codes in the regime and suggests the use of moving-mesh codes like Arepo. Although a well-considered answer to that specific paper already exists in form of Price (2012), the idea had been shown to assess our current SPH code Gadget-3 equipped with state-of-the-art schemes and compare it to matching Arepo runs. To that end we performed various turbulent simulations with both Gadget-3 and Arepo. Besides the results and analysis of these simulations, this thesis contains a concise introduction to hydrodynamics as well as to the principles of the theory of turbulence, complemented by the basic concepts of smoothed particle hydrodynamics simulations. The thesis also features an extensive appendix with most of the source code.
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Pascal Förster, 2014
Simulating Stephan's Quintet

N-Body/SPMHD Simulation of Stephan's Quintet

Based on previous studies we perform further N-Body- and SPMHD-Simulations with the code /GADGET/ on the history of Stephan's Quintet. We hereby tested different models concerning the angles of the galaxy discs and adapted masses of the original galaxies. We found well formed characteristical tails in the south-east in both models. It becomes apparent that the correction of the angles does have an influence on the outcome and especially on the detailed development of the tails. Additionaly we used the code Splotch to generate movies and appealing visualisiations of the performed simulations that illustrate the initial conditions as well as the activities during the interactions between the galaxies.
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Michael Hartmann, 2013
The Galactic
  Centre cloud G2 and scattering processes in the young stellar ring

The Galactic Centre cloud G2 and scattering processes in the young stellar ring

The origin and nature of the Galactic Centre cloud G2 is still a matter of investigation. Of special interest here was the so-called 'Compact Source Scenario' assuming a low-mass star as source for the observed cloud which could have been scattered by massive stars of the young stellar ring to its highly eccentric orbit around the black hole. In this bachelor thesis I focused on the question of the likelihood for a low-mass star originating from the young disk to be scattered on a G2-like orbit. For this, I made a rough analytical approach on the delivery rates on highly eccentric orbits by one single scattering event. As a comparison I run several N-body simulations which imitate the evolution of the orbits in the young stellar ring during its estimated lifetime of 6 Myr.
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Miriam Keppler, 2013
G2 cloud evolution

Investigation of the gas cloud G2 in the Galactic Centre

Recently, a gas cloud has been discovered with approximately three times the mass of the earth in the Galactic Centre. It is on a highly eccentric orbit around the supermassive black hole. The cloud named G2 reaches the pericentre radius of 36 light hours in summer 2013. Because of the gravitational force of the black hole the cloud is tidally disrupted. In my bachelor thesis I created a simulation using C++ for a simple scenario, where the gravitation dominates. Every other influence is neglected. Several simulations have been done before and the conclusion was that because of the disruption G2 formed most likely in 1995. But there is no mass that could form a cloud. So I started the simulation in 1944, in the apocentre, because there is a good enviroment for forming such a cloud. My simulations show that there is a possibility that G2 was formed in 1944. In that case the initial radius of the cloud and its mass are much smaller than assumed.
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Norbert Konrad, 2013
Spiral galaxies in cosmological simulations

Spiral galaxies in cosmological simulations

In recent studies of galaxy formation in cosmological simulations a angular momentum problem occurred leading to more compact disks compared to observations. Hence in this bachelor thesis we investigated some properties of disk galaxies, produced by the hydrodynamical cosmological simulation Magneticum, like morphology or rotation curves and compared our results with present studies and observations. Furthermore we studied how a extended gas disk formed at z=1.4. In conclusion we use a self developed method to characterize gas disks inside dark matter halos to investigate occurrence and position of disks within the simulated box.
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Felix Schulze, 2012
Angular momentum profiles of dark matter halos

Angular momentum profiles of dark matter halos

According to the standard theory of the formation of galactic discs within extended dark matter halos the angular momentum distribution (AMD) of the gas component initially mirros that of the dark material. Therefore in this picture the angular momentum profile of a galactic disc can be extracted from the profile of its halo host, once the latter is known. In this work we study the angular momentum profiles of a sample of dark matter halos drawn from the hydrodynamical cosmological simulation Magneticum. We investigate in detail the cumulative mass distribution of angular momentum and statistical properties of the AMDs of dark halos. Furthermore we analyse the AMDs of halos from various non-cosmological simulations. Finally we characterize the spatial distribution of angular momentum inside halos and compare several parameters of the AMDs of dark halos and galactic discs.
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Torben Erik Simm, 2012
Evolution of BHs in the centers of galaxies

Evolution of black holes in the centers of galaxies

In this bachelor thesis the evolution of black holes in the centre of galaxies was investigated especially concerning the temporal development of their accretion rates and their masses for different redshift intervals between z=6.8 and z=0.0 depending on the used simulation. It managed to point out a characteristic evolution of the black holes by the consideration of simulated findings. In order to test the conclusions drawn by analysing simulated findings, comparisons of observational and simulated data concerning the accretion rates and masses as well as concerning the luminosity function were done.
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Lucas Sommer, 2012
Cold streams in high-z galaxies

Cold streams in high-z galaxies

Halos at redshift z > 2 are thought to be fed by streams of cold gas, which leads to a high starformation rate at these redshifts. Hence, in this work we investigate several physical properties of halos with about 1012 solar masses from a hydrodynamical cosmological simulation at redshfit z = 2.33 and study how these properties evolve with time. In particular we focus on the different behavior of the hot and cold gas components.
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Adelheid Teklu, 2012
S-Stars in the Galactic Centre

On the Formation of the S-Stars in the Galactic Centre

In my bachelor thesis I tested a theory about the origin of the S-Stars around the central supermassive black hole (SMBH) in the center of our Milky Way: Infalling gas clouds gravitationally influence a test star situated in a distance of about 0.1 to 0.5 parsec from the SMBH with the result that it's orbit is bound much closer to the black hole than before. For this tests I wrote numerical simulation programs to simulate these 3-body-scenarios over a wide range for parameters like infall direction of the cloud, its speed and the orientation of the test star orbit in relation to the cloud.
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Christian Franik, 2011
Dynamics of the Milky Way - Andromeda System

Dynamics of the Milky Way - Andromeda System

In my bachelor thesis I should calculate the time of the possible collision between the Milky Way and the Andromeda-Galaxy. Therefore I created a program using Fortran, that computed the velocity and the position of the two big galaxys only under the influence of the gravitation force between them. I used the Leapfrog-method, which is more exact than the Euler algorithm, because it calculates position and velocity at different time-steps. The result was that the possible merger of Milky Way and Andromeda starts in 2 - 3 billion years. In the picture you can see the time until the two galaxies begin zu merge. The red line is the velocity of Milky Way and the green one that of Andromeda. The two horizontal lines represent the actual difference of the velocities of Milky Way and Andromeda. So the collision takes place in about 2 Gyr.
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Sheila Hieber, 2011
Massflow in cosmic filaments

Massflow in cosmic filaments

In my bachelor thesis I studied the flow of gas and dark matter in cosmic filaments. The initial point was a simulated protocluster at z = 2, performed by the GADGET 2 code. The first step was to approximate the curved filaments with cylinders. In a next step I calculated the parallel und perpendicular component of velocity and massflow. In cosmic filaments matter is first accreted to the central region of the filament where it then streams to the central galaxy cluster. The flow of the gas component is strongly dependent on temperature.
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Klaus Jakabos, 2011
Filamentary Bubbles

Filamentary structure of wind blown superbubbles

In my thesis I studied the fractal character of a simulation of two wind-blown superbubbles colliding in the interstellar medium. Molecular hydrogen is blown away from two new born stars. At the meeting point the gas shows a more and more fragmental shape. The fractal dimension was calculated via the box counting method for different thresholds of hydrogen density as well as for different time steps after star formation. Plots of different timesteps and hydrogen thresholds as well as corresponding results for the fractal dimension are shown. The fractal dimension as a function of the density threshold can also be seen.
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Birgitta Müller, 2011
The influence of central supermassive black holes on major
  merger remnants

The influence of central supermassive black holes on major merger remnants


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David Schlachtenberger, 2011