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Vacancies

PhD research topics

This page lists the available PhD projects to begin in 2020. The November 15 deadline for applications for these positions has now passed and the application process is closed.  Applicants will be informed whether they will be invited for interview by late-December/early January, with interviews to take place 13-14 February 2020.

API staff may be contacted with questions about projects, but please do not email unsolicited application materials to API staff.

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Reflected light from exoplanet atmospheres: towards rocky worlds

Supervisor: Jayne Birkby

We seek a motivated and curiosity-driven student with a passion for exploring exoplanet atmospheres and surfaces. This project focuses on the light that exoplanets reflect, and will study them initially using observations from very high resolution spectrographs, such as ESPRESSO/VLT and HARPS. The goal is to measure the planet’s reflection spectrum and use atmospheric modelling to interpret the molecular signatures detected. The program will begin with gas giant exoplanets, and will move towards sub-Saturns and Neptunes. This observational technique is still in its infancy but demonstrating its potential is key to detecting signatures of oxygen in the atmospheres of nearby rocky worlds with the Extremely Large Telescopes coming online in the mid-2020s. The project will begin with observations, but has significant scope to explore theoretical modelling and simulations as well, depending on the interests of the student. The student will become a key member of Dr Birkby’s ‘exoZoo’ team of PhDs and postdocs, supported by a European Research Council Starting Grant. The student will also be encouraged to connect with Dr Jean-Michel Désert’s and Dr Antonija Oklopčić’s respective groups in exoplanet research and explore the wider research activities in planet formation at the API too. The API offers a highly stimulating environment for exoplanet atmosphere research, with many opportunities to explore new avenues towards the characterizing of rocky worlds beyond our Solar system.

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Exoplanet atmospheres in the JWST era

Supervisor: Jean-Michel Desert

Exoplanet atmospheres allows us to learn about their composition and their overall physical properties. The main motivation of the proposed research is to answer fundamental questions about exoplanets : What is the nature, formation and evolution of the observed planetary systems? How can exoplanetology explain the origin and characteristics of our Solar System and the Earth?

To address these questions, the successful PhD candidate will develop observing programs, data analysis tools, and atmospheric models in order to study exoplanet atmospheres. This project will be supported by a portfolio of observational programs, centered around JWST, which will be used to determine the atmospheric composition, structure, dynamics, and weather patterns of exoplanets. The PhD candidate will use these new types of observations and techniques to map how planetary atmospheres respond to stellar irradiation and test fundamental predictions of atmospheric models. Ultimately, the aim of this project is to leverage exoplanet detections, as well as observational capabilities and theoretical frameworks, to deepen our understanding of (exo)planetary physics. 

We are looking for a motivated candidate with an interest in a PhD project that comprises observational and modeling expertise. The successful candidate will work within an international research collaboration. The PhD candidate will be part of a vibrant group on exoplanets and planet formation at the University of Amsterdam.

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Pinpointing the lairs of Fast Radio Bursts (funding TBC)

Supervisor: Jason Hessels

Fast Radio Bursts (FRBs) are millisecond-duration radio flashes originating long-long ago in galaxies far-far away.  Their origin is one of the most compelling astrophysical mysteries of the past decade.  Whatever produces the FRBs must be capable of providing the necessary energy density and coherence conditions to produce radio flashes that can be observed from billions of lightyears distance.  The FRBs are thus fascinating probes of extreme astrophysics in action.  At the same time, the signal properties of FRBs are deformed as they pass through the intervening ionised material local to the source, in the intergalactic medium, and the interstellar medium of our own Milky Way.  Hence, FRBs are also unique probes of this intervening material and are likely to give us impactful cosmological insights.

Precise localisation is challenging but nonetheless key to understanding the origin of FRBs, and for using them as cosmological probes.  In this project we will use the European VLBI Network (EVN) to localise FRBs to their host galaxies and to study the detailed properties of the radio bursts themselves.  The EVN is a distributed network of radio telescopes spanning the globe; as we have previously demonstrated, we can use it to localise FRBs to a precision of a few milli-arcseconds.  This is sufficient to not only identify the host galaxy, but even the exact neighbourhood within the host.  Up to two PhD positions are available within our team.

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Massive binaries: their formation, evolution and fate

Supervisors: Lex Kaper (UvA), Alex de Koter (UvA) and Gijs Nelemans (Radboud University)

Most massive stars are in binary or multiple systems; therefore, multiplicity must be a key aspect of massive star formation. Sana et al. (2012, Science 337, 444) predict that more than 70% of all massive stars will exchange mass with a companion, leading to a binary merger in one-third of the cases. Thus, multiplicity also has a fundamental impact on the evolution of massive stars. After the supernova or gamma-ray burst, compact binaries are produced hosting a neutron star (NS) or a black hole (BH), if the binary system remains bound. Also NS + NS, NS + BH, BH + BH systems may result, and their mergers may be detectable as gravitational wave (GW) sources and / or (short) gamma-ray bursts (GRBs) (e.g. Abbott et al. 2017, ApJ 848, L12). The evolution of massive stars, single and in binaries, plays an important role in understanding the chemical enrichment of the Universe. Through their stellar winds and supernovae, massive stars enrich the surrounding interstellar medium with heavy elements; the merging process of a double neutron star system has been suggested to be a key channel for the production of the lanthanides.

In order to predict the merging rate of these compact binaries, it is essential to precisely know the primordial binary population, and to carefully model the subsequent evolution of interacting binary systems. We are currently investigating the multiplicity fraction and binary properties of young massive clusters; with the release of Gaia DR3 (2021) the fraction of (astrometric) binary systems can be determined. Using this information as the initial condition of stellar population synthesis of (massive) binaries, we will predict the series of empirically identified evolutionary states these systems undergo up to their final fate as well as the statistical properties of double compact systems, and thus the number of GW sources and GRBs.

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The Apertif Radio -- Graviational wave Observatory (ARGO)

Supervisor: Joeri van Leeuwen

We can now fathom our Universe through the swell of its very fabric of  space-time: gravitational waves. Mergers of neutron stars whip up these waves, but also produce relativistic mass ejections and radio emission. Our overall goal is to understand the physics governing the interior and magnetosphere of these stars, and their spiral-in. In this PhD project we aim to discover and interpret the accompanying electromagnetic emission. We will use the novel, wide-field Apertif detectors we have recently commissioned to discover and study afterglow and prompt FRB-like radio emission from gravitational-wave events. Through precise localizations, essential for our radio, optical and high-energy follow-up, we aim to shed light on the astrophysics driving these exotic events.

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Joint gravitational wave and radio characterization of GW transients

Supervisors: Samaya Nissanke (contact) and Philipp Mösta

Extremes in the Universe, such as neutron stars and black holes and strongly-curved spacetimes, are key areas for astrophysics this century. The discovery of both gravitational wave (GW) and electromagnetic (EM) radiation from this binary neutron star merger, GW170817, has opened up a new era of multi-messenger astronomy. The EM follow-up campaign for this single event was unprecedented in terms of its scale and observational data-sets. Although only a single event, the follow-up and joint GW+EM characterization have offered new critical insights into diverse fields from gravity, high-energy astrophysics, nuclear physics, to cosmology. However, we have yet to detect and observe the prompt radio emission from such mergers and observing radio emission will allow for complementary and key information about the physics of neutron stars and black holes, as well as plasma astrophysics and magnetohydrodynamics.

In collaboration with our radio, GW and machine-learning colleagues, this PhD aims to measure and jointly interpret the physics driving the mergers through observations of their prompt and long-lived radio and GW radiation. 

We are looking for a highly motivated PhD candidate with an interest in a project that comprises both observational and modelling expertise. The PhD student will also be embedded in GRAPPA, the center of excellence in Gravitation and Astroparticle Physics of the University of Amsterdam in the multi-messenger astrophysics group of Dr Moesta and Dr Nissanke, and will interact very closely with the group of Dr Antonia Rowlinson, Dr Oliver Porth and the wider NL CORTEX collaboration. The group is active in diverse sub-fields including multi-messenger astronomy, data analysis, theory, and modeling, and is involved in the Virgo collaboration, the LISA consortium, and 3G science case, and several international electromagnetic follow-up groups.

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Atmospheric escape in exoplanets

Supervisor: Antonija Oklopčić

A significant fraction of exoplanets discovered to date orbit their host stars at much closer separations than any of the Solar System planets. These close-in exoplanets are subject to intense stellar radiation, which can have dramatic effects on their atmospheres. Upper layers of a planetary atmosphere can get heated to temperatures of several thousand degrees, creating pressure gradients that drive a supersonic outflow and allow a significant fraction of the atmosphere to escape from the planet. Atmospheric escape and mass loss can have profound influence on the extent, composition, and evolution of close-in exoplanets, and consequently, on the demographics of planetary systems.

The PhD candidate will work on theoretical modeling and/or spectroscopic observations of exoplanet atmospheres with the goal of advancing our understanding of atmospheric mass loss. The theoretically-oriented part of the project will include developing and analyzing 3D magnetohydrodynamic simulations of escaping atmospheres and investigating the roles that planetary magnetic fields, stellar radiation, and stellar wind play in this process. A more observationally-focused project will involve analyzing and interpreting spectroscopic data obtained with high-resolution spectrographs on large ground-based telescopes.

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Searching for Explosive Radio Transients with LOFAR

Supervisor: Antonia Rowlinson and Ralph Wijers

Over the past few years, radio transients at low radio frequencies have been proving elusive to find and yet we have tantilising hints that they are out there. Discoveries include a transient of unknown origin that was approximately 6 minutes long in archival data from LOFAR, unusual transients of a few tens of seconds duration by LOFAR and the LWA and exceptionally bright giant pulses from a pulsar. These transients are signposts to the most extreme physical environments and emission mechanisms in the Universe.

This project will use LoTSS, the LOFAR Two-metre Sky Survey, to conduct the deepest transient hunt to date at low radio frequencies, on timescales of ~10 seconds to 1 hour, and be the first blind multi-polarisation search at these frequencies. We aim to detect transient sources, using the LOFAR Transients Pipeline and machine learning algorithms, on the boundary between coherent and incoherent emission mechanisms and explore their likely extreme physical emission processes. 

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Ultradense matter in neutron stars (funding TBC)

Supervisor: Anna Watts

Matter in neutron star cores can reach up to 10 times normal nuclear densities, which may allow the formation of stable states of strange matter. We are studying this using a new technique called Pulse Profile Modeling, which is currently being pioneered by the NICER X-ray telescope on the International Space Station.  If applications for funding are successful there will be several projects to develop and exploit this technique both for NICER and for future large-area X-ray telescopes. The projects span dense matter, statistical inference, astrophysical theory, and observational data analysis.