Examples of PhD projects available

An overview

There will be several PhD positions open for application with a deadline of November 15, 2023. For details of the application procedure see this page. The positions are available in all the research areas in which the Observatory is active. This page will give a broad overview of possible research projects . However, research in different areas is possible and not all projects that might be offered are listed. The faculty research interests provides more background information.

• Small-scale galaxy-galaxy lensing
  Supervisor: Henk Hoekstra
  Description: How galaxies populate dark matter halos is an area of active study, because it helps to understand galaxy formation and to improve cosmological parameter estimates from large surveys, such as the one carried out by the recently launched Euclid mission. A key quantity for such comparisons is the stellar mass of galaxies, which is typically inferred indirectly through the modelling of stellar populations. A more direct measurement via gravitational lensing would allow us to test the assumptions made, and would lead to more reliable results. In this project, we will exploit Euclid's unique ability to determine the lensing signal on very small scales to extract stellar masses of ensembles of galaxies for the first time. This technique could also help us study the tidal stripping of dark matter halos in dense environments. The work involves advancing small-scale lensing analysis tools (like measuring the shapes of galaxies in dense environments) and applying these to the Euclid data.
  
  
• Constraining models of intrinsic alignments
  Supervisor: Henk Hoekstra
  Description: Gravitational lensing is not the only process that introduces correlations in the shapes of galaxies. Tidal interactions acting on galaxies also align them, compromising a straightforward interpretation of the observed cosmological weak lensing signal, such as the one we aim to measure with the recently launched Euclid mission. This intrinsic alignment signal can usually be measured directly by selecting small samples of galaxies that are close in redshift. While spectroscopic measurements are well-suited for this purpose, further information can be garnered from the Euclid data using photometric samples with more galaxies and well-characterised redshift distributions. The aim of this project is to measure the alignment signal as a function galaxy properties and redshift and use the results to inform models for the alignment signal and to confront predictions from cosmological simulations.
  
  
• Statistical Inference Techniques for Euclid-related science
  Supervisors: Elena Sellentin, Koen Kuijken
  Description: A PhD position will be available for research on cosmology with the Euclid mission to look into statical inference techniques, including building emulators for the Euclid likelihood, non-Gaussian statistics, and field-level analyses. Euclid has only recently been launched and has been designed to study dark matter, dark energy, and galaxy evolution. and will map out the large-scale structure and matter distribution to unprecedented precision, using deep galaxy imaging and gravitational lensing. It will require major advances in measurement techniques, statistical inference methods and cosmological simulations.
  
  
• Retrieving the Secrets of Exoplanet Interiors
  Supervisor: Yamila Miguel
  Description: We are in an unprecedented era for studying giant exoplanets. Over 5,000 exoplanets have been discovered, and numerous chemical species identified in their atmospheres. Current space facilities, such as TESS, Cheops, and JWST, are advancing our understanding, and future projects like Plato, Ariel, and ground-based facilities like ELT are on the horizon. At the same time, our comprehension of the giants within our solar system has evolved significantly. Missions like Cassini and Juno have been transformative, providing radical insights into Jupiter and Saturn's interiors. While the astonishing variety of newly discovered exoplanets reshapes our perspective on our solar system, a profound understanding of our native planets is crucial to grasping the fundamental physics of giant planet dynamics.
  
  In this project, the chosen candidate will develop a retrieval code to delve into the interiors of exoplanets. By combining insights from Solar System studies with the remarkable data obtained from JWST's measurements of exoplanet atmospheres, this project aims to pioneer investigations into the internal structures of planets. Objectives include determining core masses and obtaining precise metallicities, both critical to our understanding of the formation and evolution of giant planets.
  
  This project relies heavily on modelling and theoretical aspects. As such, candidates with strong programming skills are particularly encouraged to apply.
  
  
• Integrated coronagraphs and wavefront sensors for high-contrast imaging instruments
  Supervisor: Sebastiaan Haffert
  Description: Current direct imaging observations of exoplanets are limited to massive young planets, but the next generation of extremely large telescopes will unlock access to older, more temperate planets with masses and radii more like those in our Solar System. And for the first time, these telescopes will allow us to search for life on exoplanets. However, direct detection of temperate exoplanets is challenging due to the extreme contrast ratio between the planet and star that must be overcome. Therefore, it is crucial to push the technology that enables such observations. In this project the applicant will work together with Dr. Sebastiaan Haffert to develop integrated coronagraphs and wavefront sensors for extreme adaptive optics instruments for the Extremely Large Telescope. The new technology will be tested on-sky at world-leading observatories to demonstrate their potential for the ELT.
  
  
• The space weather around exoplanets
  Supervisor: Aline Vidotto
  Description: Stellar magnetic activity, in the form of high-energy radiation and stellar outflows, drives the space weather around exoplanets. High-energy radiation heats planetary atmospheres, which inflate and more likely escape. Stellar outflows cause pressure confinement around otherwise freely escaping atmospheres. How different is the space weather of exoplanets compared to Earth's? Can we detect signatures of exo-space weather? How does a harsher space weather affect close-in exoplanets and their atmospheres/magnetospheres?
  
  To tackle questions like these, we are looking for a motivated PhD student to work on the theme of "space weather" using 3D magneto-hydrodynamics simulations. The PhD candidate will develop novel 3D simulations to interpret and guide observations linked to exo-space weather. Our group has expertise in investigating both the host star (simulating stellar winds and coronal mass ejections) and the exoplanet (simulating atmospheric escape), and different projects during the PhD will look at one or both aspects. To learn more about the research of our group, please see our webpage.