Starshades sind - an Lotusblumen erinnernde - Strukturen die auf einem zweiten Satelliten in großer Entfernung zu einem einen Planeten beobachtenden Raumfahrzeug geflogen werden und mittels Beugung das Licht der "Sonne" des beobachteten Planeten abschatten. In der Arbeit soll der Stand der Technik zu Starshades zusammengefasst und die grundlegenden physikalischen Abhängigkeiten dargestellt und grafisch veranschaulicht werden.

The radio telescope at the University Observatory is used in the astro-master's practical course to measure the rotation of the Milky Way from the Doppler shift of the 21cm hydrogen line. The new telescope mount should increase the target alignment to 0.1 degrees and recover HI clouds reproducibly. For a large number of measurementsg it shall be be tested if the resolution can be increased by deconvolution of a Gaussian broadening. can be increased. Good Python knowledge is desirable.

With the upcoming Square Kilometre Array (SKA) and its precursor telescopes, radio astronomy is undergoing a renaissance. New algorithms, data reduction methods and survey modes are actively developed to handle the EB-scale raw data streams produced and to utilise the full potential of these new instruments. As part of a large collaboration, our group at LMU is developing commensal line intensity mapping and interferometric imaging using scanning observations. Such interferometric scanning or on-the-fly (OTF) observations are increasing the survey speed by removing the settle-and-slew overhead while also enabling commensal single-dish intensity mapping, providing a dramatic improvement in data acquisition efficiency. However, the scanning motion of the antennae pointing relative to the delay centre introduces smearing effects that need to be corrected in the imaging process. In particular, the smearing of the primary beam (PB) response introduces flux-density errors in the interferometric images. This project aims to model the smeared PB by measuring the flux-density variation of thousands of sources detected in our pilot MeerKAT OTF observations. The developed PB models and software will be incorporated into our OTF imaging pipeline, which we will use to reduce 100+ hours of MeerKAT OTF data observed in the upcoming year by our collaboration.

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).

Exoplanet research is a very active scientific area and a new generation of telescopes is currently being developed in order to study several of their aspects and add more discoveries. The aim of this project is to provide an overview over telescopes that are already in the planning stage and then give an outlook of the future development of astronomical observations.

Since the first discovery of an exoplanet in orbit around another main-sequence star in the year 2000, there has been a fast-growing number of exoplanet discoveries. Detected by several number of methods, their properties are quite diverse. Since the number of known exoplanets is now in the thousands it is now possible to make statistical assessments of their occurrence rate for given stellar types and the planet’s orbital periods. The aim of this project is to collect all of the current data, present each detection method and then discuss the results and their possible differences based on the detection method.

The Rossiter-McLaughlin effect (RME) has been known for decades and was initially proposed for the study of eclipsing binaries. Using this effect, the primary star’s rotation axis can be determined and this effect could first be applied to planet transits only a few years ago. The Wendelstein facility will soon be able to observe and measure this effect as one of very few observatories by using the FOCES instrument. The aim of this project is to describe the RME by compiling the according literature and then give an overview of the current results and their interesting implications for planet formation.

Super-Earths, rocky planets with radii of more than twice of Earth’s, are unknown in our own Solar system and are a distinct population of planets. The aim of this project is to describe this population, including the detection methods used for their discovery, and then provide an overview of their occurrence rate. Then, the results of their – rapidly increasing – research should be compiled.

Planetesimals are thought to form in gaseous disks surrounding young stars, but the details are poorly understood. An interesting possibility is that planetesimals actually only form from scratch under special circumstances, and most stars simply capture interstellar ones in their gaseous disk, which then trigger the formation of further planetesimals from the solid material in the disk. This project would be to estimate the number of such objects which are captured in the disk of a forming star. Depending on the interest of the student, this could be either calculated using an analytical model of the time-dependent gravitational potential well of the young star, or done numerically by analyzing the gravitational potential of the gas in a simulation.

Small grains of solid material in space (dust) could be spun up as a result of torques arising from the asymmetric grain structure and/or the anisotropic radiation field. It has been argued that the grains may spin so fast that they are ripped apart by centrifugal force. For this project, the student will study the associated literature to develop an understanding of the size distribution and lifetime of the grains that make up the interplanetary dust cloud. They could then combine this information with existing models of the grain disruption to determine whether centrifugal disruption plays a role in shaping the dust population in our solar system.

In dense ISM regions, dust grains accrete a surface layer (mantle) of ice. The thickness of this mantle is regulated by a balance between accretion from the surrounding gas, and removal as a result of transient heating following the passage of high-energy charged particles (cosmic rays) through the dust grain. We have recently shown that the balance of these two processes depends on the size of the grain, and the aim now is to explore the mantle growth in different interstellar environments. We are looking for a student to study the mantle growth in various environments with the assistance of an existing code, and to determine how the mantle thickness varies depending on the dust size distribution.

Dense gas in star-forming regions is heated predominantly by cosmic rays. A significant part of the heating is due to secondary electrons – the electrons which are produced when a primary cosmic-ray particle knocks an electron off of a molecule in the gas. We have recently calculated the energy spectrum of such electrons. These electrons lose their energy in a variety of ways, some of which heat the gas, and some the dust. We are looking for a student who will use available models for different energy loss processes to calculate what fraction of the energy goes to gas heating.

Available data allow us to construct a model of the density distribution of a filament of dense gas, located in a nearby star-forming region. These data also include measurements of the emission from two different rotational levels of ammonia molecules, which could be used to determine the gas temperature. We are looking for a student to use the model of the gas density, combined with a simple model of the spatial variability of the gas temperature, and compare this to the measured ammonia emission. This work would help us to test a recent theory that young stars act as sources of cosmic rays which may heat the nearby gas.

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.

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.

How do we measure the age of a galaxy? The Bachelor’s thesis project 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.

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.

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.

Astronomers noticed more than 100 years ago that the galaxy populations within dense galaxy clusters are different from those in the surrounding low-density field, but the underlying reasons remain unclear. Hierarchical structure formation leads dense clusters to form rather late in the Universe and to continue the accretion of surrounding material, including star forming spiral galaxies where through a range of processes they are transformed into ellipticals or S0s. Studies over the past decades have clarified the range of physical processes that are likely contributing to this transformation, and these include ram pressure stripping, mean field tidal stripping and galaxy merging, among others. We are using a new Sunyaev-Zel’dovich effect selected sample of galaxy clusters from SPT that extends to redshift z ~ 2 together with data from the DES, Spitzer, and Herschel to study these galaxy population transitions as a function of cosmic time. The goal of this project is to use the multi-band optical and IR photometry to identify cluster galaxies and study the transition in color and star formation rates as a function of radius from the cluster center as well as a function of cosmic time and cluster mass. Our dataset is uniquely suited for this study, because we have a well understood sample of clusters extending over a broad redshift range and a uniform photometric imaging dataset in the optical and IR over large areas of the sky.

Among the many facets under investigation of the galaxy formation and evolution puzzle, two old and still unanswered questions remain at the core of our incomplete picture:

1. How do galaxies grow their stellar mass over cosmic time?

   Answering this question has proven difficult mainly because of the uncertainties in estimating the on-going star formation for large, representative galaxy samples. The easily accessible ultra-violet (UV) restframe emission, in principle a direct probe of the young short-lived massive stellar populations, is in fact measuring only the small fraction of that emission that has not been absorbed by the interstellar dust. It thus needs to be corrected by factors that, depending on the intrinsic galaxy properties, can vary by orders of magnitude.

2. Why does star formation cease at a certain point during the galaxy life?

   In the last decade many studies have agreed in assigning a relevant role to nuclear activity (AGNs, due to massive black hole growth) in affecting the galaxy star formation histories (SFHs). In particular, once a major burst of star formation has eventually exhausted the gas inside the galaxy immediately available for star formation, the so-called “radio-mode feedback” is often invoked as preventing the gas in the outer galaxy halo from cooling and starting star formation again.

   Deep radio surveys, conducted in association with multi-wavelength observations, allow us to probe at the same time dust-unbiased star formation and nuclear activity, and hence have become a fundamental tool in the last decade for studying galaxy evolution. This master project will focus on already available JVLA radio continuum data in the deepest extra galactic fields in order to obtain a dust-unbiased view of star formation over cosmic time and a first-order estimate of radio-AGN feedback to be compared to theoretical model expectations at different redshifts and halo masses.

The observed bimodal distribution of local Universe galaxies in star formation properties (from optical color-magnitude and stellar mass-star formation rate diagrams) is due to the process of star formation quenching, making once star forming spiral galaxies to non/little star forming elliptical/S0 galaxies. There are many possible processes responsible for this observed star formation quenching, among which ram-pressure stripping is the dominant mechanism in dense galaxy cluster environment. The hot (10⁷ . . . 10⁸ K) and dense (n_e ~ 10⁻⁴ . . . 10⁻² cm⁻³) intracluster medium can strip cold gas from the spiral galaxy disk, which eventually truncates star formation as the galaxy moves though the cluster environment. We have acquired ultraviolet data for a sample of galaxies undergoing ram-pressure stripping (with tentacles of star formation along the stripped tails with the galaxy disk resembling a jellyfish) where the ongoing truncation of star formation can be directly studied comparing with emission line diagnostic maps made from MUSE IFU data. This project involves studying the star formation progression in a galaxy undergoing ram-pressure stripping with indications of truncation along the galaxy disk. There are opportunities to collaborate with a larger team involved in multiwavelength analysis of jellyfish galaxies.

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.

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?

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., the 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.

One of the leading methods for studying the cosmic acceleration, measuring neutrino masses and directly measuring the growth rate of cosmic structures is through studies of the redshift and mass distribution of uniformly selected samples of galaxy clusters. A key element of these studies is constraining the masses of the galaxy clusters using information from weak gravitational lensing.

The goal of this project is to use the available weak gravitational lensing mass information from the Dark Energy Survey within samples of galaxy clusters selected from the South Pole Telescope Sunyaev-Zel’dovich effect survey or the RASS (and soon from eROSITA!) X-ray survey to study the cosmic acceleration, neutrino masses, and the growth rate of cosmic structures.

• Understand the impact of surrounding large-scale structure and miscentering on the weak-lensing mass estimates of galaxy clusters. Application to real cluster sample with DES shear catalogs to constrain masses.
• Understand the impact of contaminating impacts due to X-ray and radio AGN on the selection and cosmological analysis of galaxy cluster samples.
• Measure correlations among cluster observables in the X-ray, SZE, and optical and study their impact on cosmological analyses.

• Bachelor’s and Master’s thesis projects

• Bachelor’s thesis projects of the Physical Cosmology Research Group

• Bachelor’s and Master’s thesis projects

• Master’s thesis projects of the Physical Cosmology Research Group

Gamma-ray observations allow us to study the most extreme cosmic sources in the Universe. These violent environments, which are not reproducible at Earth-based laboratories, provide opportunities to study processes at the frontier of known physics. Our group tackles a wide range of questions related to astrophysics and fundamental physics, such as probing cosmic-ray acceleration processes and the search for the nature of Dark Matter.

Over 15 years of operations, Fermi-LAT is the preeminent instrument for studying the high-energy universe in the MeV to GeV energy range. It provides a rich data set ripe for discovery of new sources and science. MAGIC is one of the current generation Imaging Atmospheric Telescopes with high sensitivity for extended sources in the Galactic Plane. The prototype of Large Size Telescope (LST) for the Cerenkov Telescope Array (CTA) has completed construction and has started partial scientific operations. Over the next four years, three additional LSTs will be built, providing unprecedented sensitivity to the gamma-ray universe. The combination of three datasets allows for highest sensitivity in studying the extreme environments within our Galaxy.

We seek Master’s students to perform their thesis work with the primary focus on the analysis of Fermi-LAT, MAGIC, and/or LST-1 data on Galactic sources such as Supernova Remnants and Galactic PeVatrons. Although not required, experience in Python and C++ is highly desired.