This page lists the currently available PhD projects to begin in 2025.

Applications needed to be submitted by November 4th. By mid-December we will invite candidates for a presentation and interviews to be held on 6 and 7 February 2025. 

API staff may be contacted with questions about projects, but please do not email unsolicited application materials to API staff. More information about the recruitment process can be found here. 

To apply for currently open positions please go to page  https://api.uva.nl/vacancies/vacancies-api.html

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Hunting for elusive companions of classical OeBe stars

Supervisor: Julia Bodensteiner (j.bodensteiner@uva.nl)

Massive stars are cosmic engines: they trigger star formation, they drive the chemical evolution of their local surroundings and their entire host galaxies, and given that a majority of them live their lives in close binary systems, their compact remnants can be sources of gravitational waves. Yet, their evolution still remains poorly understood. One of the biggest gaps in our understanding concerns the Be phenomenon: about 20% of the galactic B-type stars are so-called classical Be stars, that is stars which exhibit strong emission in hydrogen spectral lines originating in a gaseous circumstellar disk. Be stars are generally observed to be rapidly rotating, potentially near to their critical break-up velocities. The origin of their rapid rotation, however, remains widely debated. One possible formation channel of classical Be stars is angular momentum gain due to previous mass transfer in a binary system. If Be stars truly form through mass transfer, many of them should be in binary systems with an envelope-stripped companion or a compact object. Given the difficulties of detecting such systems directly, only a handful of Be binaries are known. In this observational project, we use data from a multi-technique survey – including spectroscopy, interferometry and astrometry – of a large sample of massive Be stars that will allow us to detect new Be binaries, characterize their companions and thereby provide important insights on their formation mechanism. The student will be embedded in a large international network of researchers, including experts on the different observing techniques as well as theoreticians specialized in stellar atmospheres, stellar kinematics, and the evolution of single and binary stars.

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Connecting the local environments of fast radio burst sources to their activity and burst properties

Supervisor: Ziggy Pleunis (z.pleunis@uva.nl)

Fast radio bursts (FRBs) are impulses of radio waves that last for only a fraction of a second and that are detectable over extragalactic distances. The origin of FRBs remains elusive, though various types of highly magnetized compact objects, e.g. magnetars, are favoured candidate sources. A small fraction of FRBs has been observed to repeat and the most hyperactive of repeating FRB sources produce up to hundreds of detectable bursts per hour. One key to understanding the origin of FRBs is to study their local environments in detail, which is possible because the FRB signal holds a record of all the burst's interactions with the magnetized plasma it encountered on its way. Free electrons disperse the radio waves and inhomogeneities in the free electron distribution along the way can cause multi-path propagation that lead to scatter-broadening and scintillation of the signal. Magnetic fields furthermore cause Faraday rotation of the polarized light. Especially the lines-of-sight towards repeating FRB sources can be studied in detail as the timeseries of dispersion, scattering and scintillation allow a better decomposition of the structures local to the source and other structures along the way. In this PhD project, the aim is to revolutionize our understanding of how the local environments of FRBs are connected to their activity and burst properties. This will both help us understand the nature of FRBs and make them better astrophysical tools to study the Universe at large. We will make use of world-class data from the CHIME/FRB experiment and its "Outriggers" upgrade and the LOFAR 2.0 telescope. Depending on the student's interests, there are opportunities to contribute to telescope commissioning, multi-wavelength follow-up observations and to develop skills in astrophysical modeling. The PhD student will become an expert in radio astronomy, astrophysical transients, the interstellar medium and data analysis techniques and will be embedded in the AstroFlash (https://astroflash-frb.github.io/) research group.

While prior experience in radio astronomy is not required, having a solid background in astronomy, programming and data analysis is highly valued.

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Outflows and feedback from supermassive black holes using machine learning techniques.

Supervisors: Elisa Costantini (SRON/UvA) (e.costantini@sron.nl) 

Supermassive black holes accretion and ejection mechanisms are the subject of intense study, due to their importance in the black holes origin and sustenance as well as their role in the growth and evolution of galaxies in the Universe. This project aims at the study of supermassive black holes ejection mechanisms using timing and spectroscopy techniques applied to X-ray data. Particular emphasis is given to developing and testing machine learning techniques to make use of the increasily complex models and data sets from present (XMM-Newton, Chandra, XRISM) and future (e.g. NewAthena) X-ray missions. The offered PhD position is part of the TALES (Time-domain Analysis to study the Life-cycle and Evolution of Supermassive black holes) Doctorate Network, funded by a Marie Sklodowska-Curie Actions programme. This is a consortium of 10 astrophysics research groups, 8 industrial and 4 academic partners spread across Europe. SRON, Netherlands Institute for Space Research, is one of these nodes. The student will be based at SRON, but keeping a close contact with the University of Amsterdam. The recruited researcher will have the opportunity to work within an international andmultidisciplinary team. The TALES Doctorate Researchers will be offered a broad range of opportunities for professional and personal development through numerous focused training events. They are expected to gain a unique skill-set at the interface between astrophysical modelling, astronomical observations and data science. Transnational mobility: The applicant — at the date of recruitment — should not have resided in the country where the research training takes place for more than 12 months in the 3 years immediately prior to recruitment, and not have carried out their main activity (work, studies, etc.) in that country. For refugees under the Geneva Convention (1951 Refugee Convention and the 1967 Protocol), the refugee procedure (i.e. before refugee status is conferred) will not be counted as ‘period of residence/activity in the country of the beneficiary’.

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QuickBlitz: Using short radio flashes to probe the remnants of neutron star mergers

Supervisor: Antonia Rowlinson (b.a.rowlinson@uva.nl)

Funding to be confirmed

One of the outstanding questions in studies of binary neutron star mergers is: what is the remnant formed after the merger – a black hole or a massive neutron star? There is tantalising supporting evidence for the formation of a neutron star, which is expected to have a millisecond spin period and magnetic fields in excess of 1015 Gauss. We call these supramassive neutron stars “magnetars”. Several theoretical models predict the production of coherent radio emission from these newborn magnetars. Indeed, magnetars and millisecond spin neutron stars are leading progenitor models for the elusive population of Fast Radio Bursts (FRBs). Detecting coherent radio emission following a binary neutron star merger would be a smoking gun observation for the magnetar remnant model. Using rapid response observations on low frequency radio telescopes, such as LOFAR, we have been chasing this emission following short Gamma-ray Bursts (GRBs). Recently, we found a radio flash following a short GRB that is a good candidate for this emission.

With QuickBlitz, we aim to detect coherent radio emission following binary neutron star mergers, detected via short GRBs and gravitational wave events, by rapidly triggering the upgraded LOFAR2.0 and from monitoring observations with AARTFAAC2.0 (a whole visible sky radio transient monitor using 12 LOFAR2.0 stations). To be able to confidently associate radio flashes with poorly localised binary neutron star mergers, QuickBlitz will also conduct the largest short duration transient survey to date using all LOFAR2.0 survey data in the first 5 years of operation. This survey will identify unusual radio transient sources, such as the recently discovered long period Galactic radio sources. Subject to funding, we are advertising 2 PhD positions to work on the QuickBlitz project. Successful PhDcandidates will also join the international LOFAR2.0 image plane transients team.

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Revealing the physics of magnetars through data-driven modelling

Supervisor: Daniela Huppenkothen (d.huppenkothen@uva.nl)

Magnetars, neutron stars with extreme magnetic fields, are invaluable tools for studying nature at its most extreme. Their densities allow us to probe extreme states of matter otherwise inaccessible, while their enormous magnetic fields drive some of the brightest stellar flares ever recorded. 

Despite this important role, for decades magnetars have challenged our understanding of physics in extreme magnetic fields. Recent theoretical work coupling observations to astrophysical processes in neutron stars provides tantalizing opportunities to constrain magnetic field properties and dense matter physics. Building on this, the discovery of Fast Radio Bursts (FRB), particularly the discovery of such a burst from a Galactic magnetar, has thrown the doors wide open to a major leap in our understanding of magnetars through the vast population of extragalactic FRBs, some of which are likely to be produced by magnetars. 

This project aims to determine how X-ray bursts from Galactic magnetars and radio bursts from extragalactic magnetars are linked, in order to help pin down the elusive trigger and emission mechanisms. It will use modern statistical and machine learning methods to explore the timing and spectral properties of both populations, and explore statistical connections between them. As part of the project, we will derive spectro-temporal properties of thousands of X-ray bursts and FRBs taken with world-class telescopes in space and on the ground, search for periodic oscillations and perform in-depth studies on individual sources and comparative studies across sources and wavebands to constrain emission physics and progenitor models. 

This project is designed to be interdisciplinary, with a strong data science component. As such, I welcome applications from candidates with experience in astronomy, or computer science, or statistics, or any combination. 

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New techniques for X-ray interferometry

Supervisors: Phil Uttley (UvA) (p.uttley@uva.nl) and Roland den Hartog (SRON)

This is an opportunity to play a key role in the development of a revolutionary new instrument, capable of obtaining the highest image resolution ever. We are leading an effort to develop X-ray interferometry for use in space. If successful,
we will see gains of at least 3 orders of magnitude in spatial resolution over current instrumentation, which will enable direct imaging of many energetic astrophysical environments such as the coronae of nearby stars, the accretion disks and winds of X-ray binary systems and be able to resolve pc-scale accreting SMBH binaries from across the visible universe. The focus of your PhD research will be to develop techniques and software for the X-ray interferometer optical and fringe acquisition technologies, starting with a compact prototype which we are currently building in the lab at the Netherlands Space Research Institute, SRON. Crucial to success is the development of simulation software, not only to develop the science case by simulating images of different astrophysical sources, but also to further develop and test the lab set-up and computational tools for fringe-finding and tracking, both in the lab and in space.  
Your work would develop and demonstrate some of the critical methods and technologies that would be required to fly an X-ray interferometry mission, and you would play a pivotal role in this project as it grows and develops.

The project will be carried out at the Anton Pannekoek Institute in Amsterdam, with regular visits to the lab at SRON in Leiden. Good knowledge of Python programming is essential. Some prior experience in scientific software development, high-energy astrophysics or optics/instrumentation would be an advantage.

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Supervisor: Joe Callingham (callingham@astron.nl)

Into the unknown - Discovering the stars and exoplanets emitting at low-frequencies

In this project, you redefine our understanding of radio stars and exoplanets via the development and application cutting-edge interferometric techniques to produce the deepest and most detailed radio surveys ever conducted. You will become a world expert in radio interferometry, working with the lowest frequency data to uncover radio-bright stellar systems, including potential exoplanets, and contribute to discoveries in sub-stellar object magnetism. With priority access to key LOFAR surveys and the opportunity to lead follow-up observations with top-tier telescopes, you'll be at the forefront of characterizing the low-frequency sky. This project will position you as a leader in a new and rapiding developing area of astrophysics, equipping you with vital skills for the upcoming Square Kilometer Array (SKA) era. Experience with radio astronomy would be valuable (but not a requirement).

Note: This project is jointly administered by API and ASTRON, the Netherlands Institute for Radio Astronomy. The successful candidate will be expected to spend at least 2 days a week at the headquarters of ASTRON in Dwingeloo. Such a combination will allow the candidate to experience how a research institute and observatory are operated. 

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Supervisor: Joe Callingham (callingham@astron.nl)

Hunting for the beat - Detecting periodicity from star-planet interactions

Recently, we have discovered stars emitting at the lowest radio frequencies with the radio telescope LOFAR. However, we are not certain what is exactly producing this emission. It is unclear if the emission is stellar in origin or, potentially, produced due to the presence of a close-in exoplanet. Your research will focus on searching for periodic signals from quiescent stellar systems - the expected signpost of a star-planet interaction. With access to hundred of hours of pre-approved LOFAR observation time, you'll be well-equipped to make revolutionary discoveries. This project not only offers the chance to become a world leader in low-frequency stellar system research but also position you with skills that will be valuable in the upcoming Square Kilometer Array (SKA) era. Experience with radio astronomy, exoplanet, or stellar science would be valuable (but not a requirement).

Note: This project is jointly administered by API and ASTRON, the Netherlands Institute for Radio Astronomy. The successful candidate will be expected to spend at least 2 days a week at the headquarters of ASTRON in Dwingeloo. Such a combination will allow the candidate to experience how a research institute and observatory are operated. 

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Supervisor: Sera Markoff (s.b.markoff@uva.nl)

Understanding the source of the highest energy particles, as part of a large European team

We are constantly bombarded by cosmic particles on Earth. At lower energies the solar wind is the primary source, but we also detect particles (“high-energy cosmic rays") from the MeV to >EeV (10^6-10^18 eV and beyond) that come from yet-unknown cosmic accelerators. While the origin of cosmic rays (hadrons, ions, neutrinos) in our Galaxy is still unclear, the highest energy particles above 10s of PeV (above 10^15-10^16 eV) were traditionally thought most likely to originate in the jets of Active Galactic Nuclei (AGN). However the field has been undergoing a major shift just in the last few years, with some puzzling results using "multi-messenger" information from gamma-rays and neutrinos.  In the simplest scenarios, cosmic rays are accelerated and interact locally to create these two signals, such that their fluxes should roughly match.  It seems, however, that they do not, and that the most promising neutrino sources are preferentially associated with only weakly-jetted sources.  These observations pose a major challenge to long-standing ideas about particle acceleration in these systems.  Meanwhile, via the Event Horizon Telescope, we finally have the chance to directly observe the near event-horizon regions of not only Sgr A* and M87, but also the inner jets of several other nearby AGN associated with high-energy gamma-rays and neutrinos.  

The successful candidate will work in Sera Markoff's group, which has a strong track record in developing and using both semi-analytical and numerical methods to model accretion and jets around black holes of all scales, both for EHT sources as well as X-ray binaries. This particular position will focus on advancing the semi-analytical models of hadronic processes in jets to fit multi-messenger data, as well as integrating new information from simulations in order to study jet dynamics, cosmic ray acceleration and interactions, and the feedback of jets on their environments.  

This project is funded as part of an ERC Synergy Grant, Blackholistic, a partnership between The University of Amsterdam, Radboud University, the University of Oxford, and the University of Namibia, and is affiliated with the Event Horizon Telescope collaboration.  We encourage applications from diverse candidates who have experience in, and enjoy, coding and modelling, and who enjoy the idea of working in a large and dynamic international team, including spending time at different international institutes for collaboration.