Bachelor thesis with Prof. Mertsch in 2018

 

Acceleration of cosmic rays at galactic wind termination shocks

Supervisor: Philipp Mertsch

Context:
The earth is constantly bombarded by a flux of charged particle from outer space, called cosmic rays, some with energies up to 10^{20} eV. Most cosmic rays are thought to be accelerated by the blast waves left behind by supernova explosions. However, at the highest energies these sources cannot reach the required energies. Instead, giant shock waves surrounding our Galaxy could be the site of acceleration to extremely high energies.

Goals:
In this project you will analytically or numerically compute the spectrum of cosmic rays accelerated at galactic wind termination shocks and find ways of testing the model by comparing with observations.

Requirements:
Familiarity with solving basic partial differential equations and an interest to learn about high-energy astrophysics!

Dark matter limits and cosmic-ray anisotropic diffusion

Supervisor: Andrea Vittino

Context:
Cosmic rays can be produced by standard astrophysical sources or by the annihilation or decay of dark matter. Most dark matter searches rely on the assumption that cosmic-ray transport in the Galaxy is isotropic with respect to the direction of the Galactic magnetic field. However, this might be an over-simplification, as several theoretical and experimental arguments seem to point towards anisotropic diffusion. Taking this anisotropy into account could potentially have an impact on dark matter searches.

Goals:
You will be able to use a numerical code for cosmic ray transport to propagate the particles from dark matter annihilation or decay. By comparing to measurements from the AMS-02 experiment on the International Space Station you will be able to find dark matter (!) or constrain its properties.

Requirements:
Some familiarity with C++ and python would be good.

Galactic loops and inflationary gravitational waves

Supervisor: Philipp Mertsch

Context:
A key prediction of cosmological inflation is the generation of gravitational waves that can be measured as a polarisation pattern in the cosmic microwave background. The detection is complicated by the foreground of microwaves produced in the Galaxy. A good understanding of the polarisation patterns and their spectrum is needed to make further progress.

Goals:
You will model and characterise the various structures that contribute to the microwave emission of the Galaxy: supernova remnants, radio loops, filamentary structures etc. This can be done numerically or (in some approximation) analytically. Eventually, one would want to quantify the effect on the cosmological observables.

Requirements:
Some general experience with coding would be good.

Cosmic ray anisotropies and interstellar turbulence

Supervisor: Andrea Vittino

Context:
The distribution of the arrival directions of cosmic rays (high-energy charged particle from outer space) shows lots of structure that can help in better understanding their transport across the Galaxy as well as the underlying properties of the turbulent interstellar medium.

Goals:
You will numerically track particles through turbulent magnetic fields and predict their arrival directions. This can be used to predict gamma-ray emission around postulated sources of high-energy cosmic rays or to model the puzzling structure in their arrival directions.

Requirements:
Some familiarity with C++ and python would be good.