Examples of PhD projects available
There are currently several PhD positions open for application
with a deadline of December 15, 2013. 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 gives 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 and
the general overview of the research at the Observatory
provide more background information.
- Constraints on Reionization and Distant Clusters, Observational:
Extragalactic Observational Research with the Dutch-European
radio telescope LOFAR: The Dutch-European radio telescope LOFAR
will open up the last unexplored window of the electromagnetic
spectrum for astrophysical studies and make important contributions to
our knowledge of the formation of structure in the universe. PhD
positions with Huub Rottgering are available on the following three topics:
- Forming massive galaxies at the epoch of reionisation. LOFAR will
detect radio galaxies at unprecedented distances close to or even at
the epoch when the universe makes a phase transition from neutral to
ionised. LOFAR radio spectroscopy targeting associated neutral
hydrogen 21 cm absorption would, for the first time, determine
physical characteristics of the gas at this crucial epoch. Studies of
these galaxies will constrain models of how massive galaxies and
associated massive black holes are formed.
- Diffuse synchrotron emission associated with the first bound
clusters of galaxies. Currently, diffuse radio synchrotron sources are
known in about 50 nearby massive galaxy clusters. LOFAR has the
potential to detect many thousands of these systems, up to an epoch when the
first bound clusters appear. Studies of the associated shock waves
produced by cluster mergers and magnetic field properties of the
cluster gas will constrain models of the formation of galaxy clusters.
- Starbursting galaxies. LOFAR will detect radio emission from
millions of star-forming galaxies at an epoch at which the bulk of
galaxy formation is believed to occur. In combination with infrared
surveys, this will enable studies of how the physics of star formation
differs between high and low density regions in the universe.
- Theoretical and/or Observational Studies of Hypervelocity Stars: One Phd project
with Dr Elena Maria
Rossi on Hypervelocity star theory, catalogue searches and data modelling.
Hypervelocity stars are stars which travel at an enormous speed
through our halo, and they are thought to originate from the Galactic
Centre. The relativistic potential of the central black hole, SgrA*,
is indeed the only possibility to impart such a phenomenal kick to a
star. The project aims to develop a model for formation of
Hypervelocity stars and predict observables (such as velocity
distributions) that will be compared with upcoming GAIA data. GAIA
sample of hypervelocity stars will be of extraordinary quality and
quantity. Comparing data with models will allow us to put
unprecedented constraints on the Milky Way Galactic Potential and the
star population in the Galactic Bulge. This information is vital to
understand galaxy formation in general.
- ALMA: Pending availability of funding, one or two PhD positions may be available to study the structure and composition of planet-forming disks, using the Atacama Large Millimeter Array as well as advanced simulations. The objectives of the studies include the characterization of the disk structure and search for possible signatures of ongoing planet-formation, localization of the snow line inside disks, and comparison to the frozen record in Solar System comets. The research will be carried out under supervision of Michiel Hogerheijde.
- Star formation in dwarf galaxies:
The group of Jarle Brinchmann has an opening for a PhD position within the MUSE guaranteed time project. MUSE is a new instrument for the VLT that will enable resolved spectroscopy with good resolution over 1'x1'. The GTO team has been awarded 250 nights of time on this instrument and this PhD project will be carried out in the context of these data. The student will be closely involved in the observations and reduction of the data with a focus on studying dwarf galaxies with extremely low star formation rates. The goal here is to find these systems and to understand their properties - with a focus on their star formation and interstellar medium properties.
- Solid-state Laboratory Astrophysics -- Forming complex molecules
in space: This PhD research project concerns the simulation of
the chemical processes that take place on the surfaces of dust grains
in star- and planet-forming regions in interstellar space. This
research project will make use of fully operational state-of-the-art
UHV surface science experiments in which interstellar ice analogues at
temperatures of 10-90 K are bombarded with atoms and/or UV radiation
(see www.laboratory-astrophysics.eu for more information).
The focus within this PhD project will be on nitrogen-containing
molecules. The laboratory experiments are directly linked to
astronomical observations on complex organic molecules from the
Atacama Large Millimeter Array (ALMA). The research will be directed by
Prof. E.F. van Dishoeck
and Prof. H. Linnartz.
We are looking for an enthusiastic person with a background in
instrumentation, experimental physics, physical chemistry, surface
science or laboratory based astrophysics.
- Exoplanet geology: gas en dust from hot, rocky exoplanets
Prof.dr. Ignas Snellen & Prof.dr. Christoph Keller
This PhD project will focus on two new ways in which we can learn about the surface and interiors of close-in rocky exoplanets: I) through sputtering, a process well known from Mercury in our own solar system, in which surface elements are released into space through a heavy bombardment by the intense stellar wind plasma, and II) through the disintegrating of the most extremely irradiated planets, which subsequently release large amounts of gas and dust into an exospheric tail. The first of these disintegrating planets, discovered by Kepler, KIC 22557548b, shows a highly variable tail.
- Finding the brightest transiting planet-systems in the sky - MASCARA
Prof.dr. I. Snellen
In a few months, the first station of the Multi-site All-Sky CAmeRA MASCARA will become operational. Its aim is to find the brightest transiting exoplanets in the sky, between V=4-8, which will be highly valuable for atmospheric characterization. This PhD project will focus on the first data - selecting the best candidates, conduct follow-up observations, and discover the true exoplanets.
- Observations of Faint Galaxies in the Early Universe:
lowest luminosity galaxies in the early universe likely play the dominant
role in both the production of metals and the reionization of the universe
and likely contain the bulk of the stellar mass. However, their properties
remain somewhat poorly constrained. We should be able to greatly improve
our characterization of faint galaxies in the early universe using
ultra-deep spectroscopic observations -- which we will obtain using a
powerful new spectrograph MUSE to be commissioned on the Very
Large Telescope in Chile -- in combination with deep Hubble+Spitzer
observations over the Hubble Ultra Deep Field and over cluster fields
where one can benefit from the lensing magnification of the faint high-redshift
universe. The new MUSE observations should allow for order of magnitude
gains over existing studies and benefit from the substantial time allocation
appropriated to the MUSE GTO team. There will be an opening for a new
PhD student in the group of Rychard
Bouwens to take advantage of these observations to obtain a much improved
understanding of this important population of faint galaxies in the early universe.
- Galaxy formation:
The group led by Joop
Schaye has an opening for a PhD student to work
on models of the formation of galaxies and the
evolution of the intergalactic medium. Possible projects include the analysis of the EAGLE simulation, a ground-breaking cosmological, hydrodynamical simulation using 7 billion particles, and the development of new, high-resolution smaller volume simulations that include more physics such as non-equilibrium chemistry and/or radiation transport. Projects with a data analysis component are also possible.
The PhD student will become part of an international team.
- Physics and chemistry of the interstellar medium:
Prof.Dr. Xander Tielens
The interstellar medium plays a key role in the evolution of the Milky Way and other galaxies. It is the repository of the ashes of earlier generations of stars and the birthplace of future generations. Molecules and small dust grains play an active role in this evolution. Moreover, their emission can be used to probe the characteristics of the region and the processes therein. Key questions in this field are the role of molecules and dust in the processes that drive the evolution of galaxies, the organic inventory of space particularly regions of star and planet formation, and the growth of dust in protoplanetary disks.
Leiden Observatory has an active program in the physics and chemistry of the interstellar medium, combining observational studies - mainly in the infrared and sub-millimeter - with space based (Spitzer Space Telescope & Herschel Space Observatory) with ground based (Very Large Telescope) observations and laboratory studies. The focus is on the lifecycle of interstellar gas and dust in the Milky Way during its sojourn from its stellar injection sites such as Asymptotic Giant Branch Stars and supernovae, through the turbulent cloud and inter cloud phases of the interstellar medium, to its final incorporation into newly formed stars and planetary systems. One focus of these studies is on the composition, origin, and evolution of large Polycyclic Aromatic Hydrocarbon molecules and their role in the interstellar medium. Another focus is on the related topic of the characteristics of stardust grains and their evolution in the interstellar medium. There are direct links to other groups in Leiden Observatory, to other groups in Holland through the Dutch Astrochemistry Network, and to several groups at the international level.
The ISM group currently has some ten graduate students and five postdocs. Within this group there are opportunities for graduate student(s) in the general area described above. While the topics are somewhat flexible, one position is envisioned to focus on the physical characteristics of nano grains – the transition from large molecules to small dust grains both theoretically and observationally. The other position would focus on the chemical evolution of large molecules in protoplanetary disk environments. This astronomical model study would be based upon laboratory studies in Leiden and Amsterdam but also includes the analysis and interpretation of astronomical infrared data. In addition, depending on funding, there may be an opening for a graduate student focusing on a LOFAR survey of the Milky Way in Carbon Radio Recombination lines in order to determine the physical conditions in the diffuse ISM.
Requirements are a broad interest in and good understanding of the physics and chemistry of the interstellar medium, background and experience in observational, experimental, or theoretical techniques relevant to this research area and a willingness to interact across scientific disciplines. While students work on their own PhD projects, good interaction with others in the group will be key to success.
- The role of the Cold Neutral Medium in Galactic evolution, Observational/Theoretical:
Dr. Raymond Oonk, Prof.dr. Xander Tielens, Prof.dr. Huub Rottgering
The interstellar medium (ISM) is the repository of stellar ejecta and the birthsite of new stars and, hence, a key factor in the evolution of galaxies over cosmic time. The cold neutral medium (CNM) is a key component of the ISM, but so far this phase has eluded detailed studies, because its main tracer, the HI 21 cm line, does not constrain basic physical information of the gas (e.g., temperature, density) well.
We are studying the CNM through low-frequency carbon recombination lines (CRRL), which do provide a unique, sensitive probe of the physical conditions in cold, atomic clouds. With its unprecedented sensitivity, frequency resolution and multibeaming capability, LOFAR enables us to perform efficient surveys of the sky which will revolutionize the field of low-frequency recombination line studies and our understanding of the CNM.
A PhD position with Raymond Oonk, Xander Tielens and Huub Rottgering is available on one of the following two topics:
- Medium resolution all-sky Galactic CRRL survey: LOFAR will perform a CRRL survey of the Galactic plane, deriving, for the first time, a comprehensive inventory of the CNM in our Galaxy from degrees down to 10' scales. This will allow us, to quantify its role in the overall pressure, carbon abundance, mass and energy balance of the interstellar medium.
- High resolution CRRL observations of bright Galactic sources: LOFAR will perform very high-resolution (10'' at 60 MHz and 3'' at 180 MHz) observations of bright Supernovae and Starforming regions in the Milky Way. These observations will allow us for the first time to resolve the CRRL emitting gas across individual atomic gas clouds and determine the role of the CNM in the cycles of star formation and death.
- X-ray diagnostics of clusters of galaxies
Dr. Jelle Kaastra (SRON)
Two PhD positions are available for X-ray studies of clusters of galaxies. The major fraction of normal matter in clusters of galaxies consists of hot X-ray emitting gas. Its thermodynamics and chemical history are still not well understood. In this project we will study three key questions related to this gas. What happens with cooling gas in the cluster core? Weak, but characteristic spectral signatures of charge exchange emission that occur at the interface of the hot and cold gas may contain the answer. How do the shocks that heat the gas work? Clues can be found in spectral signatures of non-thermal electrons, detectable through specific enhanced X-ray lines. And where and when were the metals in this gas formed? The abundances of many chemical elements and their spatial distribution in the hot gas provide key information about the cluster's chemical history.
High-resolution X-ray spectroscopy is the exclusive tool to study all these processes. The Astro-H observatory, to be launched in 2015, will enable us to obtain high-resolution spectra of clusters for the first time. We will analyse these data to address our key questions. The first year of the PhD, before the launch of the satellite, will be used to improve the X-ray spectral models. The work will be done in a team consisting of staff, PhD students and postdocs at SRON, Utrecht, with regular visits and collaboration with staff at Leiden.
- From Disks to Exoplanets: exploring the astrochemistry of planet formation
Prof.dr. Ewine van Dishoeck
A 4-yr PhD position is available at Leiden Observatory. The research
concerns the simulation of chemical processes in the planet-forming
regions of protoplanetary disks and will explore the link between
disk physical structure and chemistry and the eventual composition of
(exo)planetary atmospheres. This research project will make use of
state-of-the-art computational modelling, astrochemical methods, and
laboratory data to simulate both the physics and chemistry of
protoplanetary disks and the formation of gas-giant planets within
The focus of this PhD research will be coupling chemical models of
protoplanetary disks around young stars with evolutionary tracks of
forming planets to identify physical and chemical parameters which
influence the resulting planetary atmosphere composition. These
simulations will be compared with astronomical observations of nearby
protoplanetary disks with the Atacama Large Millimeter/Submillimeter
Array and observations of molecules in the atmospheres of exoplanets
and the Solar System gas giant planets. The research will be
directed by Dr. C. Walsh and supervised by Prof. E. F. van Dishoeck.
We are looking for an enthusiastic and motivated person with a
background in astrophysics, astrochemistry, physical chemistry, or