PhD research topics

This page lists the available PhD projects to begin in 2019. 

We will be offering multiple positions across most areas of research carried out at the Anton Pannekoek Institute.  Topics and project descriptions (where available) are given below.  Further details and new projects may be added over the next few months, so please check back here in case of any updates.  

If you are interested in working in a particular research area (or project, if listed), please indicate this in your cover letter, but note also that we will consider applicants for a variety of the positions being offered, so it is not obligatory to list specific projects.  Also please note:  all application materials should be submitted via the general application process.  API staff may be contacted with questions about projects, but please do not email unsolicited application materials to API staff. 

 

 

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Observations and modelling of exoplanet atmospheres

Supervisor: Jayne Birkby

Observing exoplanets at high spectral resolution is a powerful technique for characterizing the composition, structure, and dynamics of their atmospheres. The student will lead the analysis of spectra from a large survey of exoplanet atmospheres with the 6.5-m MMT telescope and ARIES spectrograph. They will investigate the properties of different hot gas giant exoplanets, performing comparative exoplanetology to begin understanding how the planet formation process results in such incredible diversity. They will study the chemical and physical processes occurring in extreme planetary environments and use these to define classes of exoplanet. They will further have the opportunity to propose observations for CRIRES+/VLT for smaller planets like mini-Neptunes. They will work closely with a postdoc on the theoretical modelling of the planet atmospheres, and help devise techniques to combine these data with space-based data and extract maximal information about the planet’s atmosphere, properties, and formation history.

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Exoplanet observations

Supervisor: Jean-Michel Desert

Exoplanet atmospheres allow 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? How can we look for and identify signatures of life on exoplanets ?  To address these questions, the successful PhD candidate will develop observing programs, data analysis tools, and models in order to learn about exoplanet atmospheres and their host stars. This project will be supported by existing observational exoplanets programs from space-and-ground based surveys, including VLT, HST, JWST. In particular, the candidate will work on UV observations of exoplanets and hosts stars using the CUTE cubesat that will be launched in spring 2020. The candidate will work within an international research collaboration and develop techniques to study the impact of stellar irradiation and activity on exoplanet atmospheres.  We are looking for a motivated candidate with an interest in a PhD project that comprises instrumental, observational and modeling expertise. 

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The role of PAH & dust aggregation in protoplanetary disk physics

Supervisor: Carsten Dominik

The vertical structure of protoplanetary disks plays a key role in a number of physical processes, such as dust aggregation, that are crucial to understanding planet formation and the organic inventory of regions of planet formation.  Resolved imaging of protoplanetary disks at multiple wavelengths allows us to image disk midplane and surface both in dust grain tracers and polycyclic aromatic hydrocarbons (PAHs), showing that in some disks, PAHs and small grains are abundant and present in the disk surface, while not visible in others, with consequences for disk structure, chemistry and dynamics.  Observations with ALMA, SPHERE and soon with JWST are providing crucial new insights, so it is time to develop new models for dust aggregation in dusty protoplanetary disks and study the astrophysical consequences.  The successful candidate will develop such models, apply them to protoplanetary disks under a variety of conditions and use them to help interpret the wealth of new data becoming available. 

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Massive star formation: linking the formation process to pre-main-sequence evolution

Supervisor: Lex Kaper

Our current understanding is that massive stars form in a way similar to low-mass stars, i.e. through disk accretion. However, the formation timescale is expected to be much shorter, on the order of 10,000 years. In the protostellar phase massive disks are observed, e.g. with ALMA, while the central object is obscured from view such that the physical properties of the forming stars are difficult to determine. Taking advantage of the sensitivity and broad wavelength coverage of VLT/X-shooter, we recently identified massive pre-main-sequence stars that are still surrounded by a (remnant) accretion disk, contracting towards the main sequence (Ellerbroek et al. 2013, Ramirez-Tannus et al. 2017,2018). The main aim of this project is to observationally and physically link the formation phase of massive stars to the outcome of the formation process that we encounter in the youngest massive clusters. We want to do this by measuring the velocity and density structure of the massive disks detected by ALMA and to compare this to the disk properties exhibited by the massive pre-main-sequence stars. These two important phases in massive star formation are currently very distinct, even though in time they should be closely linked. We also want to search for evidence for the formation of massive binaries: one of the scenarios invokes the development of spiral-like structure in the disk that may result in the formation of a companion star (e.g., Meyer et al. 2017). Our ultimate goal is to better understand the formation process of massive stars.

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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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Supernovae and compact object mergers

Supervisor: Philipp Moesta

Extreme core-collapse supernovae and compact object mergers belong to the most energetic transients in the universe and are the primary sources for multi-messenger gravitational wave astronomy with advanced LIGO. Understanding the fundamental physics and observational signatures of these events is one of the key topics in modern theoretical astrophysics. The possible projects in this field will rely heavily on numerical simulations to reveal the engines driving these transient events and the connection of these engines to their observable signatures. A main focus will be on the modeling of lightcurves and spectra, but heavy-element nucleosynthesis, the connection to stellar evolution via progenitor systems, and more fundamental relativistic astro-/plasma- physics aspects can also be explored.

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Dissipation mechanisms and emission from relativistic jets 

Supervisor: Oliver Porth

Relativistic collimated outflows are present in a number of diverse high-energy astrophysical objects ranging from gamma-ray bursters over X-ray binaries to active galactive nuclei.  The mechanisms leading to non-thermal emission and energy dissipation are however barely understood.  We will use state-of-the art (general) relativistic magnetohydrodynamic simulations to explore routes of plasma instability leading to heating and particle acceleration.  
The results will shed light on jet internal turbulence and the physical pathways behind the mini-jet model invoked to explain the fastest variability in gamma-ray bursts, active galaxies and pulsar wind nebulae.

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GRMHD simulations of accreting neutron stars 

Supervisor: Anna Watts

Weakly magnetic accreting neutron stars have variable X-ray luminosities due to variation in the flow of accreted plasma onto the neutron star surface.  The variation can be very rapid (frequencies up to 1 kHz), and is more noisy than for accreting black holes - most likely due to the presence of a boundary layer between the neutron star surface and the accretion flow, in which much of the gravitational potential energy is released.   Due to the high frequencies and proximity to the neutron star surface, the signals produced in this region may contain information that lets us constrain the dense matter equation of state.  However to to understand accretion variability on dynamical time-scales close to the NS we need to use GRMHD simulations, which are challenging because of the need to include radiative processes due to the strong heating in the small boundary layer region.  State-of-the-art simulations should be up to this challenge: the goal of this project is to extend them to model accretion on to neutron stars, coupling them to relativistic ray-tracing models to determine the resulting spectral-timing-polarimetry signatures in the X-ray emission.  The results will be directly applicable to the next generation of large-area X-ray telescopes, in which API scientists are heavily involved.

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Mapping the close environments of accreting black holes and neutron stars with NICER

Supervisors: Phil Uttley and Anna Watts

Funding for this project is still to be confirmed, but if awarded, we will be offering two PhD positions in this area.  The projects will focus on using spectacular new data from the NICER X-ray telescope (operating from on board the International Space Station since June 2017) to map the inner regions of accreting black holes and neutron stars in X-ray binary systems.  As researchers on this topic, you will use advanced `spectral-timing' techniques which combine X-ray spectral and variability information, combined with physical modelling of the spectral-timing signatures, to infer the inner region structure, the effects of strong field gravity on the matter dynamics and constrain key physical parameters such as black hole spin and neutron star mass and radius.

Published by  Anton Pannekoek Institute for Astronomy

16 November 2018