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Department of Astrophysics

Available Master & Bachelor projects

Galaxy Formation

Diversity in the low mass galaxy population

Observations show that low-mass galaxies fall into several broad morphological classes such as ultra-diffuse galaxies, dwarf elliptical galaxies, compact elliptical galaxies, and others. Current numerical models struggle in reproducing this diversity in the low mass galaxy population. The goal of this project is to more robustly quantify this problem and to explore improvements to the modeling to solve this challenge. To this end, we will analyze low-mass galaxies in suites of state-of-the-art cosmological simulations and compare the predicted morphologies, especially their sizes and rotation curves, faithfully with observational data of nearby low-mass galaxies.

Contact: Prof. Robert Feldmann


Disk galaxy formation

When and how galaxies form stable, thin disks is still not fully understood. A recent model proposes that disk formation is closely linked to the depth of the gravitational potential in the center of galaxies. First, we will test this model prediction and explore its limitations using a large suite of cosmological simulations. Secondly, we will analyze the properties of both the gas and stellar disks in more detail and compare them to available observational data. Finally, we will make predictions for when the first disk galaxies are expected to form in the Universe.

Contact: Prof. Robert Feldmann


Inferring galaxy properties with Machine Learning

Galaxy properties, such as their masses or star formation rates, are usually observationally inferred from the magnitudes and colors of galaxies. However, interstellar dust can strongly affect these measurements. In many cases, the impact of dust is modeled in a highly simplified and idealized manner which could in principle lead to significant biases in the inferred galaxy properties. In this project, we will use galaxies from a cosmological simulation which have been processed with radiative transfer to quantify these biases and to test how well we can recover intrinsic galaxy properties. As second part, we will train a deep neural network on the simulations to predict intrinsic quantities from mock images and apply it to a real observational data set.

Contact: Prof. Robert Feldmann
 

Holes in atomic gas disks

Gas disks of galaxies often show distinct holes which may be created by stellar feedback, turbulence in the interstellar medium, and other processes. The goal of this project is to study holes in the atomic gas disks of simulated galaxies, to quantify their properties, and to determine how they formed. In addition, we will develop a machine learning based classifier to automatically distinguish the different physical origins of holes in atomic gas disks.

Contact: Dr. Jindra Gensior, Prof. Robert Feldmann

Large-scale structure of the Universe, relativistic N-body simulations

My group works with N-body simulations of cosmic structure formation, ray tracing and statistical analysis of simulation data. We can offer projects with the aim to extract statistical features from the distribution of matter in the Universe. Examples include

- A project to develop improvements to the two-point correlation function estimator for large, high-quality data sets

- A project to study the effect of relativistic frame-dragging on the statistics of gravitational weak-lensing tangential shear

Contact: Prof. Julian Adamek

Planet formation and evolution, planetary interiors, extra-solar planets

Giant planet formation and evolution

Giant planets play a key role in the formation and dynamical evolution of planetary systems.  Their origin, however, is still poorly understood. In this project we will use numerical simulations to model the formation and evolution of giant planets with the aim to provide predictions on their compositions and final masses of the planets. We will explore the formation of the outer planets in the solar system as well as of giant exoplanets. 

Contact: Ravit Helled


Exoplanet characterization

Planets orbiting other stars are detected at a rapid pace. When both the mass and the radius of a planet are measured, the average density of the planet can be determined. In order to understand what exoplanets are made of, structure models are required. In this project we will characterise exoplanets using interior models, to put limits on their bulk compositions and internal structure, and when possible, link it to their formation and evolution histories. 

Contact: Ravit Helled  


Giant Impacts of clumps

Protoplanetary disks that are massive enough can fragment leading to the formation of clumps that could evolve to become giant planets. Simulations suggest that several clumps form in such disks. The interactions between these clumps and their potential collisions that can lead to both mergers and fragmentation are poorly known. In this project we plan to simulate the collisions between gaseous clumps using SPH simulations and determine their fate for a large range of initial and impact conditions.
Contact: Ravit Helled & Joachim Stadel

Theoretical Astrophysics and Cosmology

Cosmological Observables in the Tetrad Formalism

Cosmological observables such as galaxy clustering, cosmic microwave background anisotropies are measured in the local rest frame of the observers. The tetrad formalism provides a natural way to describe the local observations. The linear order perturbation computations can be performed in the tetrad formalism, connecting the local observables to the cosmological observables in a gauge invariant way.

Contact: Prof. Jaiyul Yoo

 

Pulsar Timing Signatures from Ultra-Light Dark Matter

Recently, international collaborations of pulsar timing array reported  evidence for stochastic gravitational wave background. These signals, however, can also come from dark matter in our own Galaxy. The nature of dark matter is poorly understood, and rapidly oscillating light scalar fields as a dark matter candidate can result in rapidly oscillating gravitational potential that can mimic the signals in the pulsar timing array. Here we explore their contributions to PTA signals and ways to distinguish from stochastic gravitational wave background.

Contact: Prof. Jaiyul Yoo