Examples of PhD projects available

An overview

There will be several PhD positions open for application with a deadline of December 1, 2022. 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.

  • PhD positions on Euclid-related science
    Several positions are available for research on cosmology with the Euclid mission, a new space telescope which is designed to study dark matter, dark energy, and galaxy evolution. Euclid is most likely to be launched in 2023, 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. At least 3 positions are available in Leiden, in the context of the national 'Dark Universe Science Collaboration':
    • cosmology from weak lensing and large-scale structure, using Euclid data and FLAMINGO cosmological simulations (with Kuijken, Hoekstra, Schaye)
    • statistical inference techniques for Euclid: including building emulators for the Euclid likelihood, non-Gaussian statistics, and field-level analyses (with Sellentin, Kuijken)
    • Testing modified gravity theories with Euclid: including developing accurate predictions for the large-scale structure in different theories, using bespoke cosmological simulations (with Silvestri, Schaller)
    • The relation between galaxies and their dark matter halos: simulations of structure formation predict how galaxies populate dark matter halos and how their shapes are aligned. Improving our understanding of these relations is important for the cosmological analysis of Euclid data and to correctly account for intrinsic alignments (with Chisari, Hoekstra)
    • small-scale weak lensing: determining the stellar masses of galaxies and measuring the density profiles of satellite galaxies using Euclid data. This work involves developing the analysis tools and the interpretation of predictions from simulations. (Hoekstra)

    PhD students in DUSC are part of a national network of Euclid-related research, with regular meetings, co-supervision and exchange of ideas.

  • The next generation of interior models for giant planets
    Supervisor: Yamila Miguel
    Summary: The key to understanding the solar system formation history lies in the distribution and abundance of the heavy elements in the interiors of the giant planets. In these exciting times, with exceptionally accurate gravity data provided by the Juno mission and Cassini Grand Finale, we have a unique opportunity to study the interiors of giant planets with unprecedented detail. In the classical view, giant planets are composed of a small core surrounded by a homogeneous, convective gaseous (2-layer) envelope. In contrast, recent Juno data suggests differently (Miguel et al., 2022), resulting in a paradigm shift in our view of the interiors of the giant planets. An inhomogeneous interior with compositional gradients may inhibit convection. Consequently, the temperature and the amount and distribution of heavy elements in the interior will change. Interior models that fit current data do not consider this physical regime, and they are time-consuming, making statistical analysis difficult. We desperately need to implement these new findings in the next generation of models to get robust estimations of the interiors of the giant planets.

    In this project, the PhD student will go beyond the state-of-the-art with new interior models for Jupiter and Saturn with non-homogenous interiors and using Neural Networks, providing the community with open source tools to study the interiors of the giant planets with unprecedented details.

  • Understanding the origin of wide separation directly imaged gas giant exoplanets
    Supervisors: Matt Kenworthy, Yamila Miguel
    Recently our group has been successful in detecting directly imaged gas giant exoplanets around young stars that are similar in mass to the Sun through the Young Suns Exoplanet Survey (YSES). We have detected two planets with masses of 14 and 6 Jupiter masses around YSES 1, and a third planet of 6 Jupiter masses orbiting at about 110au from another solar type star, YSES 2. The YSES survey is not yet complete, but we have been awarded the telescope time to finish this survey and also start an expanded survey called Wide Separation Planets in Time (WiSPiT), where we expect to detect more exoplanets such as these. All these planets are at unusually wide distances from their parent star, from 110 to 320au, far away from where we expect planets to form. We are starting a project with one PhD and one postdoctoral position to work on the observational and theoretical origins of this new population of gas giant exoplanets. Both will work together on the project.

    The PhD position will focus on the observational aspect of the project: (1) completing the YSES survey to determine the occurrence rates of large separation exoplanets, (2) following up the orbital determination of the YSES exoplanets to determine their orbital pericenters and eccentricities, (3) running the WiSPiT survey observations and data analysis, interspersed with telescope proposal writing for ESO telescopes and JWST followup.

  • The tilting rate of the MW disk
    Supervisor: Anthony Brown
    Hierarchical structure formation models for the MW predict that the dark matter halo tumbles at a typical rate of a few tens of μas/yr, which suggests that the MW disk orientation may also vary in time. Modelling by Earp et al. (2019) showed that the tilting rate of the disc is well correlated with the gas inflow rate, and that the warp provides a good indication of the direction of the tilt. Interactions with satellite galaxies such as the LMC may lead to a rotation of the angular momentum vector of the disk population. It has been estimated (Perryman et al 2014) that the time varying MW disk orientation should be measurable in the Gaia data, provided the reference frame defined through quasars observed by Gaia is inertial to sufficient accuracy. This project is aimed at researching how to make this measurement in practice from the Gaia data. A successful measurement of the time variation of the MW disk angular momentum vector would provide insights into the accretion history and dynamical state of the MW as well as the ongoing interactions with massive satellite galaxies such as the LMC and the Sagittarius dwarf galaxy. It is not guaranteed that the time variation of the MW disk orientation can be measured, one of the problems being that it may not be possible to define 'the disk' uniquely in terms of a fundamental plane. However, even an estimate of the upper limit on the orientation variation would lead to insights into the questions above and in addition provide valuable information on how the measurement is affected by systematic errors in the Gaia astrometry and reference frame. This in turn would provide guidance on the future requirements on high accuracy astrometry and reference frames.

    This PhD project is part of the MWGaiaDN MSCA Doctoral Network. The network consists of 10 academic partners across Europe at which 12 PhD students will be active in the network researching a range of topics with Gaia and other data.

  • Stellar Dynamics of Galactic Nuclei
    Supervisor: Dr Elena M. Rossi

    Galactic nuclei - the stars, gas and compact objects in the inner few parsec at the center of a galaxy, are fascinating objects: they are the densest stellar systems in the Universe and they contain at their center a Massive Black Hole (MBHs) that dominates the dynamics in the innermost central region. A notable example is the Centre of our own Milky Way, which can impact the behavior and evolution of the whole galaxy. Galactic Nuclei are the site for a large diversity of phenomena involving stars and compact objects that are visible in both electromagnetic and gravitational waves. This is primarily a theoretical position, looking for a talented or aspiring dynamicist, where analytical and some computational skills will be developed and applied. The PhD candidate will build theoretical models to both interpret and predict observables that can allow us to examine the difficult to directly observe environment around a MBH, and to ultimately understand the assembly history of both MBH and galactic nuclei.

  • Numerical Simulations of Tidal Disruption Events and their Interpretation in Data
    Supervisor: Dr Elena M. Rossi

    A Tidal Disruption Events (TDE) is the disruption of a star by the tidal field of a Massive Black Hole (MBH) at the center of a galaxy. It is a theoretical position where especially computational skills will be developed and applied. TDEs are observed as flares that last for months and sign post an otherwise quiescent and therefore invisible MBH. They are especially frequent around the elusive Intermediate Mass Black Holes (IMBHs < 1 million solar masses), which make them extremely promising as IMBH finders. The knowledge of the IMBH population is ultimately important to understand the origin of MBHs in the Universe. In order to extract the MBH properties a deep understanding of the dynamical and radiative properties of TDE is needed, which can only be reached with state of the art simulations on supercomputers. The PhD candidate will run a suit of hydrodynamical simulations with radiative transfer to understand and characterise TDE observables for a large range of source parameters. Ideally the results of these simulations will form a data modeling library that the PhD candidate will apply to ZTF data to discover and caracterise IMBHs,

  • Adaptive Correction of Optical Wave Phase and Amplitude distortions
    Supervisor: Niek Doelman
    Optical waves propagating through atmospheric turbulence experience random fluctuations on both the amplitude and phase of the electric field. For long, outdoor propagation ranges this may lead to significant beam spread, beam wander and irradiance fluctuations at a receiving telescope.

    Adaptive correction of both wave phase and amplitude distortions can be a powerful approach to reduce the detrimental impact of atmospheric turbulence on the optical beam. This correction is based on real-time measurements of the wave distortion. In its classical form, Adaptive Optics - as currently implemented at large-aperture astronomical telescopes - aims at correcting the wavefront phase-only.

    The main challenge in this research project is to correct for wave phase and amplitude errors. This would lead for instance to reduced fading in Free Space Optical Communication channels. Alternatively in the direct imaging of exo-planets, it would enable to reach higher contrast levels.

    The research study includes: real-time sensing of wavefield distortions, tomography of atmospheric turbulence profiles and multiple-deformable mirror configurations. Outdoor field tests for the verification of the adaptive correction strategies are foreseen.

    This research is part of the NWO-funded Perspective program Optical Wireless Superhighways. In this program new concepts and technologies for broadband and secure data communication are developed. A total of 15 PhD researchers, distributed over 9 research groups from 5 Dutch universities are joining forces with 16 knowledge institutes and industries to explore these opportunities at all length scales: ranging from ultra-long links between satellites, to short links within indoor rooms.

  • Wavefront correction for high-contrast imaging of exoplanets using Microwave Kinetic Inductance Detectors
    Supervisors: Pieter de Visser (SRON) and Matthew Kenworthy (Leiden Observatory)

    Microwave Kinetic Inductance Detectors (MKIDs) are superconducting single photon detectors, which can detect each individual photon and determine its energy. The energy information allows to take a spectrum without dispersive optics and to distinguish wanted signal from dark excitations. Therefore, these detectors can have truly zero dark current, in contrast to commonly used semiconductor cameras. These properties make them a strong detector candidate for the characterization of Earth-like exoplanets, which are very faint, and to answer the question whether these planets host life.

    This instrumentation project particularly focusses on the demonstration of an MKID camera as a wavefront sensor for the biggest telescope that is now built on the ground, the ELT, for which the current wavefront correction technology is not accurate and fast enough to achieve the desired contrast between exoplanets and their host stars. You will work on an experimental wavefront sensing- and correction demonstration, using MKIDs, which will involve optical design and simulations and novel algorithm development, to make optimal use of the single photon colour and arrival time information of the MKIDs.

    You will work at both SRON, the Netherlands Institute for Space Research and Leiden Observatory (which are neighbours), and combine the detector development at SRON with the astronomical instrumentation at the Observatory. You will work closely together with another PhD student who will focus on the detector development.

  • Understanding the fuelling of AGNs
    Supervisor: Prof. Serena Viti
    High-resolution observations of molecular gas have shown to be essential for our understanding of how active galactic nuclei (AGNs) are fuelled. These observations have revealed that the large amounts of energy, released during the feeding process, can regulate gas accretion through the launching of molecular outflows in different types of active galaxies: these outflows are a manifestation of AGN feedback. Thanks to a multi-cycle ALMA campaign, we have collected a set of CO transitions observed at different spatial resolutions in the circumnuclear disk of one of the closest composite galaxies, NGC 1068. This thesis project will focus on the studies of the CO line profiles and ratios in order to understand the kinematics of the gas surrounding the AGN. In particular, there will be an observational component consisting of the analysis of the CO datasets in order to correlate the changing profiles and ratios with the kinematics of the region, and a second component which will deal with the construction of a dynamical model of the outflow+AGN coupled with our chemical models. An extension to other AGN-dominated galaxies is also envisaged. This PhD project is part of MOPPEX which is a 5 years project funded by an Advanced Research Grant from the EU.

  • Observational Characterisation of Exoplanet Atmospheres
    Supervisor: Ignas Snellen

    Over recent years, enormous advances have been reached in the characterisation of extrasolar planets. While we learn about atmospheric physics and the climatological circumstances of these exotic worlds, we also hope to comprehend their formation and evolution through their chemical and isotope ingredients. In our group we are particularly focusing on ground-based high-dispersion spectroscopic observations. The PhD student will work on the forefront of this field, using state-of-the-art instrumentation such as CRIRES+ and ERIS.

  • A high resolution X-ray spectroscopy perspective on supermassive black hole feedback
    Supervisors: A. Simionescu and L. Gu

    This project investigates how the most massive black holes in the Universe stir the matter and metals around them over distances millions of times larger than their own size. Working at both SRON, the Netherlands Institute for Space Research, and Leiden Observatory (which are neighbours), you will have preferential access to some of the first data obtained from the X-ray Imaging and Spectroscopy Mission (XRISM), expected to be launched in mid-2023. The high-resolution X-ray spectra obtained by XRISM will provide unprecedented constraints on the dynamics and chemical composition of the hot (10-100 million K) atmospheres surrounding the most massive central galaxies in groups and clusters. You will collaborate with an established group of experts both in-house and worldwide to obtain a fresh look on how supermassive black holes are intimately connected to the fates of their host galaxies, and how chemical elements are spread and distributed across the cosmic web.