Opportunities for Master Students

Two projects for master students (MPhys) are available for the academic year of 2016-2017.

1) Origin of ultra-high-energy cosmic rays
2) High-Energy Gamma Rays as Probes of Intergalactic Magnetic Fields

Good knowledge of C++/Python is required. Details can be found here.

A short summary of the projects can be found below.

Origin of ultra-high-energy cosmic rays

The origin, nature, and mechanisms of acceleration of the most energetic particles in the universe, the ultra-high-energy cosmic rays (UHECRs), are unknown. During their propagation from their source to Earth, they can interact with the cosmic microwave background and the extragalactic background light, and also be deflected by intervening magnetic fields (both galactic and extragalactic).

Many models have been proposed to explain how cosmic rays are accelerated to such high energies, and common candidates for sources are active galactic nuclei, tidal disruption events, and magnetars, among others.

In this project the student will use catalogues of astrophysical sources to simulate the propagation of UHECRs from possible sources to Earth, considering all relevant energy loss processes as well as deflections in magnetic fields. By analysing several models and comparing the results of simulations with measurements it will be possible to obtain model-dependent constraints on the sources of UHECRs.

High-Energy Gamma Rays as Probes of Intergalactic Magnetic Fields

Magnetic fields are observed in several scales, from planets to clusters of galaxies. The origin of cosmic magnetic fields in the universe is an open problem in cosmology. There are two classes of models to explain the cosmological magnetogenesis: primordial and astrophysical mechanisms. The existence of non-zero magnetic fields permeating the whole universe, henceforth called intergalactic magnetic fields (IGMFs), may be deemed a signature of the former process, thus suggesting the existence of a ubiquitous field since early times.

High energy gamma rays can probe the universe up to relatively high redshifts as they are electrically neutral and their arrival directions can be approximately traced back to their source. The interaction of the high energy gamma rays with ambient photons from the cosmic microwave background and the extragalactic light can produce electromagnetic cascades, whose short-lived charged component is affected by intervening magnetic fields, allowing us to study these fields.

The goal of this project is to constrain IGMFs using observations of blazars by gamma ray telescopes, and confronting these data with simulations. By finding the best fit model, it will be possible to derive lower bounds on the strength and coherence length of IGMFs.

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