Postgraduate program
We offer several STFC studentships per year to work within one of the group's research areas as detailed under "research". These studentships are also open to non-UK EC citizens (although only the fees part is paid in this case). In addition, there are University Research Scholarships and Overseas Research Scholarships (each year the deadline for the latter is January so early applications are encouraged). Further details of the application process can be found on the department's postgraduate admissions pages, where information on financial support can also be found.
Our group's research interests are outlined here. The following projects are intended as examples which can be tailored to individual interests.
Star Formation and Feedback
Our group carries out observational and theoretical studies of massive star formation, and the effects of these stars on their surroundings. On the observational side we have recently completed surveys of the Galactic Plane at mid-IR and radio wavelengths that have yielded the largest, well-selected samples of massive young stellar objects and ultra-compact H II regions to date. The Leeds group has led these two major international survey projects and is heavily involved in other ongoing Galactic Plane surveys at near-IR, far-IR, sub-millimetre and radio wavelengths. On the theoretical side we have expertise in the hydrodynamical and magnetohydrodynamical (MHD) interaction of high Mach number flows, and the effect of adding ablated/evaporated material from cold clumps into these flows. We use state-of-the-art dynamical codes to study these interactions, and radiative transfer codes to simulate observations, aid the interpretation of the data, and drive future observations.
How do Massive Stars Form?
Massive stars control much of the evolution of galaxies. Their intense
output of ultraviolet radiation, stellar winds and ultimate demise as
supernovae shapes the interstellar medium. The formation of such
massive stars throws up interesting puzzles since that same high
luminosity repels infalling material preventing growth during the
early stages. This feedback takes the form of fast ionized jets and
winds, whilst still deeply embedded in the dense molecular cloud. In
this project you will use two new state-of-the-art radio surveys to
study the ionized feedback from massive stars in the process of
forming. The first uses the UK's new e-Merlin array to map the radio
continuum emission at unprecedented resolution and sensitivity in a
well-selected sample of massive young stellar objects for the first
time. You will take charge of the reduction and analysis of these data
and compare with model predictions. 
The second survey is a recently
completed high resolution survey of the Galactic plane with the
VLA. This has yielded a complete set of data on ultra-compact H II
regions that form once the young massive star ionizes the surrounding
molecular material. You will investigate their dynamical expansion
which can both enhance and quench further star formation. Both
projects have scope for follow-up observations using radio and mm
interferometers such as e-Merlin, EVLA, CARMA and ALMA. Overall the
project will lead to a major increase in our understanding of the role
and nature of feedback during massive star formation.
For further details contact: Prof Melvin Hoare
The earliest phases of high mass star formation
Our understanding of the initial conditions of high mass star formation is poor due to lack of detailed observations toward well selected targets. Thanks to Spitzer and Herschel space observatories, it is now possible to find dark, massive and quiescent clumps within giant molecular clouds and follow up their study with ground based observations. This project will start with the reduction and analysis of recent APEX observations of a sample of starless massive clumps in different dense gas tracers such as SiO, N2H+ and deuterated species. Comparison with extinction maps obtained with Spitzer and dust temperature maps from Herschel will then be performed. This will allow us to obtain physical and chemical properties as well as kinematics of quiescent massive clumps. Interferometric data (including EVLA and ALMA) will be requested during the project. They will be combined with single dish data, to establish the internal structure of the selected objects and compare it with nearby starless low-mass cores. This will allow us to shed light on the first steps toward the formation of massive stars and stellar clusters and thus put stringent constraints on the theory.
For further details contact: Prof Paola Caselli
The stripping of protoplanetary disks and dwarf galaxies
Accretion disks surround young stars during their formation. Such disks are responsible for the formation of planets. However, high speed winds and photoionizing radiation from nearby massive stars may strip the disk of material and prevent planet formation. On much larger scales, dwarf galaxies orbiting within massive galaxy clusters may have their interstellar medium stripped of material due to the ram pressure the galaxy experiences from the diffuse gas in such clusters. In recent work we have shown that the stripping of material is dependent on the turbulent nature of the interaction. However, many details of these scenarios have yet to be elucidated. The PhD student will use and further develop a state-of-the-art hydrodynamical code to simulate these interactions, and examine and interpret the results obtained. This work will yield further insight into many key astrophysical problems, including the conditions under which planets may form and the evolution of galaxies and the gas in the intracluster medium.
Figure showing the stripping of
material from the interstellar medium of the galaxy NGC 4402 which is plunging through
the gas within the massive Virgo cluster of galaxies (centre downwards
in this image). The curved and truncated disk is an indicator of this
process. Credit: H. Crowl (Yale University) and WIYN/NOAO/AURA/NSF.
For further details contact: Dr Julian Pittard
High Energy Astrophysics
Our group is involved in the study of the high-energy universe
measuring the very highest energy gamma rays and cosmic rays.
Cosmic
accelerators are supposed to produce cosmic rays and gamma rays
simultaneously and, thus, a "multi-messenger" approach promises a
deeper understanding of the sources and acceleration processes
involved. Group members are involved in the Pierre Auger Observatory, the largest
cosmic ray detector ever built, to measure ultra-high energy cosmic
rays with energies > 1018 eV, and in the projects VERITAS, HESS and CTA to investigate
sources of 1011 - 1014 eV gamma rays. Recent
results from Auger have been the first detection of cosmic ray
anisotropies, hinting at nearby AGN as sources of the accelerators,
and the measurement of a break on the energy spectrum due to
interaction of cosmic rays with the cosmic microwave radiation. Also,
first results on the mass composition of cosmic rays have been
obtained. HESS and VERITAS have recorded gamma rays from more than 80
sources with a wealth of data on very different types of sources,
establishing ground-based gamma ray astronomy as its own discipline. Many
surprising results on pulsar wind nebulae, AGNs, X-ray binaries, micro
quasars and other sources have been found, and even quantum-gravity
and dark matter models have been constrained. Now design efforts for
the Cherenkov Telescope Array (CTA) are underway, an instrument
consisting of an array of 50-100 optical telescopes which provide a
10x better sensitivity than existing observatories. CTA will be able
to detect > 1000 sources. Example postgraduate projects in high-energy astrophysics are:
Analysis of data from the Pierre Auger Observatory: The main objective of Auger is to identify what these cosmic rays are, where they come from and how they are accelerated to these huge energies. The constant stream of data allows many exciting analyses on the cosmic ray energy spectrum, their mass composition and the arrival direction distribution.
Shower Simulations: Astroparticle physics experiments often use the interactions of cosmic particles with large volumes of target materials on Earth. To interpret the measurements numerical simulations of the showers of secondary particles in the target material are needed. The simulations are a challenging, as massive computer resources are needed and some of the physics inputs are still uncertain. The project aims at the improvement of the simulations for better analysis of Auger and HESS data and the design of CTA.
Design of the Cherenkov Telescope Array: CTA is a next generation observatory for gamma rays which is ten times more sensitive than current instruments such as HESS or VERITAS. CTA will probe the emission of astrophysical sources in the energy range ~30 GeV to >100 TeV using an array of 50-100 optical telescopes. Leeds is leading the efforts to optimise the design of this £100 million instrument. There are opportunities for students to work on the design of CTA and on the analysis and interpretation of gamma-ray data from current detectors.
For further details on all of these projects contact: Dr Johannes Knapp
Further Information
Interested parties may also contact the postgraduate admissions secretary for further information:Ms. Faith Bonner
Email: physics.pg.admissions@leeds.ac.uk
Phone: +44 (0)113 34 33839