GRAPPA MSc Thesis Projects

 

The following projects are Master Thesis Projects that have been defined by GRAPPA faculty members. Other thesis projects may also be available, please contact the relevant faculty members. See also GRAPPA members’ research interests. Please note that this is an evolving list, so come back in the future.

See the list of completed thesis projects.

Projects with a September 2017 start:

Testing a generic primordial black hole population as a dark matter candidate by looking at radio and X-ray sky 

 The first direct detection of a gravitational wave signal, announced by the LIGO collaboration, demonstrated the existence of ∼30M black holes (BHs), prompting the suggestion that these objects are of primordial origin and may account for all of the Dark Matter in the Universe.

The presence of a population of primordial black holes in our Universe is heavily debated in these days in the scientific community, and in particular the possibility that these objects account for all the Dark Matter can be tested and constrained in many different ways, exploiting both cosmological and astronomical data.

If the Dark Matter is actually made of massive primordial black holes, there should be ~10^9 such objects in the Galactic bulge, and — given the large amount of gas in the inner part, close to the Galactic center — we expect them to accrete gas and show up as radio and X-ray sources in the sky 

We derived constraints on this hypothesis by comparing to the known X-ray and radio sources  in the Galactic center region (VLA and X-ray catalog), but those constraints are based on the assumption of a Dirac delta mass function.

The project consists in extending our results to arbitrary mass functions, in order to get a more robust and general constraint on the amount of primordial black holes in our Galaxy, in the 1 – 100 Msun mass range. The result may be an interesting and timely matter of debate in the astroparticle community and may result in a publication in a journal.

The student should have some experience in C/C++ coding: A package aimed at simulating the X-ray and radio emission from a population of PBHs is already present, and needs to be extended to generic mass functions. The student is expected to have some knowledge on the Dark Matter problem in general, and will acquire specific knowledge on the primodial black hole physics, and the physics of accretion of matter onto an isolated black hole.

Contact: Daniele Gaggero, Gianfranco Bertone

What constitutes gamma-ray sky around 1 GeV?

Ando et al. (arXiv:1701.06988) recently analysed the angular power spectrum of the diffuse gamma-ray photons collected with the Fermi-LAT instrument, and found that the blazars, the most dominant gamma-ray source in the GeV sky, cannot explain the measured level of anisotropy by themselves. Especially around 1 GeV, the data suggest need for new population of gamma ray sources. Since the sources have to be rare and bright individually in order to contribute strongly to the angular power, they might have already been detected as Fermi “unassociated” sources. The purpose of this project is to study the properties of these unassociated sources carefully, and see if they can explain the required angular power around 1 GeV. The study will uncover not only the origin of the gamma-ray background but also the nature of this entirely unknown population.

Contact: Shin’ichiro Ando

What makes up the neutrino sky?

A few years ago, IceCube telescope at the South Pole detected high-energy neutrinos (TeV-PeV) from extragalactic sources. These neutrinos come from isotropically from every direction of the sky, and at the moment, there is no way to tell what astrophysical sources produce them. In the near future, however, by using the angular pattern of these neutrinos, one should be able to identify sources, either individually or statistically. Ando et al. (arXiv:1701.02165) pointed out that the use of the angular power spectrum of the IceCube neutrinos collected with current detector configuration was already enough to exclude some major population of the sources such as active galactic nuclei power by supermassive black holes. The project will adopt careful modelling of the source distribution as well as position-dependent exposure maps to give quantitative assessment of what sources can be tested with the current and future neutrino data.

Contact: Shin’ichiro Ando

Visualization of information geometry for new physics searches

Progress in astroparticle physics and searches for particle dark matter is driven by the comparison of theoretical models with experimental data. During this process, forecasting the sensitivity of existing or future experiments for the detection of astrophysical or new physics signals is a ubiquitous task, usually requiring the calculation of detection thresholds and projected upper limits. The concept of Fisher information is a powerful tool to perform such forecasting. Fisher information provides an answer to the question “what is the maximum extractable information from a given observation for a given model?”. Interestingly, the Fisher information matrix gives rise to a metric on the space of model parameters. It hence can be studied with the tools of differential geometry. The volume implied by the Fisher information matrix is here an indicator for the expected information gain that a specific new instrument can provide.

Goal of this project is (1) to apply the abstract concept of “information geometry” to a few examples of new-physics searches, and (2) to develop a new efficient method for the visualization of the Fisher information matrix (visualization of two-dimensional tensor fields). The student should have, or acquire during the project, knowledge in programming (Python, R or Julia), general relativity and cosmology, and basic statistical methods, and should come with an appetite for data visualization.

Contact: Christoph Weniger

The cosmology of dark relics from a Frequentist’s perspective

Dark relics from the Big Bang could appear today as cold, warm or hot dark matter, or as dark radiation. Cosmological observations of the Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations, and, e.g., the number of Milky Way satellite constrain the amount of these dark relics in the Universe. The analysis of data is usually done in a Bayesian framework, which allows to consistently combine the results from several experiments. However, a Bayesian analysis requires the definition of prior probabilities, which introduces a degree of subjectivity in the analysis. This can be avoided in a fully Frequentist approach.

Goal of this project is to set up a Frequentist analysis of cosmological data, and use this to constrain dark relics in the Universe over a large range of masses and velocity dispersions. The student should have, or acquire during the project, knowledge in programming (Python and C++), cosmology, and basic statistical methods. The project will require the manipulation of existing software tools (CLASS, MontePython), and distributed parallel computing.

Contact: Christoph Weniger

Analysis of extended gamma-ray emission with SkyFACT

The study of the gamma-ray emission from the Galaxy plays a major role in nowadays astroparticle physics. The extremely accurate Fermi-LAT maps provide an unique opportunity to shed light on the physics of cosmic-ray propagation in different regions of the Galaxy. Moreover, the existence of an anomalous excess towards the center may be either a case of indirect detection of dark-matter annihilation or the first sign for a dense population of millisecond pulsars in the bulge, and thus represents one of the hottest subjects of investigation.

We developed a new tool (SkyFACT) for the analysis of diffuse gamma-ray data, which is an innovative hybrid between image reconstruction techniques and traditional template analyses, using up to a million model parameters. This tool can be used to study the excess emission in the inner galaxy, as well as other extended emission components along the Galactic disk.

Goal of this project is (1) to explore how SkyFACT can be parallelized on computing clusters to allow a higher analysis resolution, and (2) to study the morphology and emission properties of various extended emission regions along the Galactic disk, in order to gain useful information on the cosmic-ray spectrum in different regions of the Galaxy, and on the origin the anomalous emission from the bulge.

The student should have, or acquire during the project, experience in programming (Python, bash scripting), gamma-ray astrophysics, and basic statistical methods.

Contact: Christoph Weniger, Daniele Gaggero

Searching for X-ray signatures of dark matter

The recent discoveries of an unidentified X-ray line in several different astrophysical sources, which could plausibly be the result of dark matter decay, generated much excitement in the astrophysics community. However, these sources, which include our own Milky Way, the nearby galaxy M31, and a sample of galaxy clusters, host hot gas that emits both continuum and line emission in the X-ray band, which makes separating a dark matter signal from an astrophysical one difficult. One of the most promising targets to search for a potential signal of dark matter are dwarf galaxies, which have masses that are dominated by dark matter and also host very little gas, and therefore have low backgrounds. The detection of an X-ray line in a dwarf galaxy, combined with the more tentative detections in other objects, would strongly suggest a dark matter origin.

The goal of this project is an analysis of X-ray observations of the Draco dwarf galaxy, in order to constrain a potential signal from dark matter decay and test the robustness of any signal against different background models. Over the course of the project, the student would learn both X-ray spectroscopy and techniques for dark matter indirect detection. A good candidate for this project would be enthusiastic about X-ray data analysis and dark matter modeling, but prior knowledge of either is not required.

Contact: Christoph Weniger, Emma Storm

Probing Fundamental Physics with Gravitational Waves

The recent detection of gravitational waves by the LIGO collaboration was a landmark event.  It marks the dawn of a new era of gravitational wave astronomy and precision tests of gravity.  In this thesis, the student will explore what can be learned about the fundamental laws of physics from future gravitational wave observations. In other words, how does physics beyond standard model (of both particle physics and gravity) manifest itself in the gravitational wave signals?
The nature of the project will be exploratory, so the precise research direction will be developed in collaboration with the supervisor and is expected to evolve over time.  The thesis will require a strong background in theoretical physics, especially in quantum field theory and general relativity.

Contact: Daniel Baumann

Data Analysis on XENON1T

The XENON collaboration has started to take data with the XENON1T detector, which will be the world’s most sensitive direct detection dark matter experiment. The Amsterdam group is playing an important role in this experiment. The detector operates at the Gran Sasso underground laboratory and consists of a so-called dual-phase xenon time-projection chamber filled with 3200kg of ultra-pure xenon. Our group has an opening for a motivated MSc student to do data-analysis on this new detector. The work will consist of understanding the signals that come out of the detector and in particular focus on the so-called double scatter events. We are interested in developing methods in order to interpret the response of the detector better and are developing sophisticated statistical tools to do this. This work will include looking at data and developing new algorithms in our Python-based analysis tool. There will also be opportunity to do shifts at the experiment in the underground laboratory in Italy.

Contact: Patrick Decowski

Dark Matter R&D with XAMS

The Amsterdam Dark Matter group has built an R&D xenon detector at Nikhef. The detector is a dual-phase xenon time-projection chamber and contains about 4kg of ultra-pure liquid xenon. We plan to use this detector for the development of new detection techniques (such as utilizing new photosensors) and to improve the general understanding of the response of liquid xenon to various forms of radiation. The results could be directly used in the XENON1T experiment, the world’s most sensitive direct detection dark matter experiment at the Gran Sasso underground laboratory. We have several interesting projects for this facility. We are looking for someone who is interested in working in a laboratory on high-tech equipment, modifying the detector, taking data and analyzing the data him/herself. You will “own” this experiment.

Contact: Patrick Decowski


OLD PROJECTS:

Gamma-ray Observations of Clusters of Galaxies: Dark Matter and Cosmic Rays

Clusters of galaxies are the latest and largest gravitationally bound structures to form in the Universe. About 80% of their mass is in form of dark matter and therefore they are prime targets where to look for gamma-rays from dark matter annihilation or decay. The Perseus cluster of galaxies is particular promising both for dark matter and for searches of diffuse gamma-ray emission from cosmic rays. You will analyse the data of the Fermi – Large Area Telescope NASA satellite for the Perseus cluster, including a detailed astrophysical modelling of the background sources, in search for diffuse gamma-ray emission from dark matter and cosmic rays, and eventually interpret the analysis results in term of theoretical models.

Contact: Shin’ichiro Ando, Fabio Zandanel

Extra-galactic Radio Background from Clusters of Galaxies

The ARCADE-2 collaboration found an excess of background radio emission over known sources and backgrounds across the sky that remains a puzzle today. A possible explanation is that this is due to the combined emission of all unresolved clusters of galaxies in the Universe. This emission could be due to products of dark matter annihilation/decay and/or from cosmic rays accelerated at structure formation shocks. In this project, you are expected to study and model these two possibilities and find under which conditions these could explain the ARCADE-2 excess, making, at the same time, predictions for the current and future generation radio telescopes.

Contact: Shin’ichiro Ando, Fabio Zandanel 

Beyond the standard lore of gamma-ray production from cosmic rays

A major puzzle in nowadays astroparticle physics is the existence of an excess in gamma rays towards the center of our own Galaxy. This unknown excess in the diffuse gamma-ray emission may be a case of indirect detection of dark-matter annihilation, and thus represents one of the hottest subjects of investigation. The dark matter signal, however, could be mimicked by astrophysical processes, such as Inverse Compton (IC) emission from cosmic rays (CRs) accelerated in the Galactic bulge. A major issue in the characterization of this signal is assessing such a contribution. Conventional models of CR production and propagation are not adequate to describe the emission from the inner Galaxy with sufficient accuracy and a significant improvement in our understanding of these processes is required.
The project aims at developing innovative models of anisotropic CR transport in order to understand whether the gamma-ray emission from CRs may have morphological and spectral features compatible with the anomaly. We are looking for students with some expertise in C++ coding, who are willing to expand existing numerical packages in order to develop and test such models.

Contact: Christoph Weniger, Francesca Calore, Daniele Gaggero

Extreme Astronomy – Preparing for CTA, the Next-Generation Gamma-Ray Observatory

The Cherenkov Telescope Array (CTA) is a planned facility for measuring gamma rays from space covering more than four orders of magnitude in energy, up to energies exceeding 100 TeV. CTA employs the imaging atmospheric Cherenkov technique to measure properties of cosmic gamma rays. This technique is based on measuring Cherenkov light emitted during the development of a gamma-ray air shower. CTA will be built at two experimental sites, one in the Northern, one in the Southern hemisphere, and will consist of up to 100 telescopes. It represents a major leap forward in sensitivity and precision for gamma-ray astronomy, and will allow us to explore very-high-energy processes of the extreme Universe at an unprecedented level.

Several master projects are available in the CTA group of UvA and the students will participate in photonic and electronic R&D studies contributing to the starting phase of CTA. These studies will either focus on laboratory-based measurements or simulations of novel kinds of single-photon detectors, referred to as silicon photomultipliers (SiPMs). By means of these simulations the performance of SiPMs used for arrays of Cherenkov telescopes will be assessed and their optimal operational parameters will be evaluated. Within one of the laboratory-based projects different types of SiPMs will be characterized and a measuring system to calibrate the photo-sensors will be designed and operated. In a different project various imaging and non-imaging light sources will be used to study the trigger performance of a CTA prototype camera.

Contact: David Berge

Diffuse supernova neutrino background

Core-collapse supernova explosions emit tremendous amount of neutrinos. These neutrinos form diffuse background radiation in the present Universe. Studying such neutrino background tells us information about supernova mechanisms, neutrino properties, and star formation history. The purpose of this project is to predict the flux of the diffuse neutrino background by taking into account the developments of the field.

Contact: Shin’ichiro Ando

Secret interactions between neutrinos and dark energy

If dark energy interacts with neutrinos in a secret manner, it might modify the pattern of neutrino oscillation. This effect is known to be energy dependent, being enhanced at higher energies. The highest energy neutrinos measured so far are the ones detected with IceCube at South Pole. The IceCube further found that the flavor ratio was consistent with 1:1:1. Here, you are expected to study the implication of this IceCube measurement for such secret neutrino-dark energy interactions, and constrain the energy scale of the interaction.

Contact: Shin’ichiro Ando

Other Projects

Here is a list of MSc research projects that are available at Nikhef.