Supervisor: Dr. Ian Stevens

1) The Cygnus OB2 Radio Survey (COBRaS)*

Massive stars (such as O, B and Wolf-Rayet stars) are the energetic engines of galaxies, driving star-formation, outflows, energizing and enriching the interstellar medium. The large masses mean they have extreme luminosities and prodigiously strong stellar winds that shape and effect their environments. Massive stars also predominantly occur in binary systems with other massive stars leading to the phenomenon of colliding stellar winds, resulting in substantial X-ray emission and also non-thermal radio emission, which is not yet fully understood. This project focusses on the population of massive stars in the Cygnus OB2 star-forming region.

A large component of the project will involve working on the E-Merlin COBRaS survey of the Cygnus OB2 star-forming region, which is the central portion of the larger Cygnus X star-forming region.

Cyg OB2 is the nearest massive star-cluster and is likely to be a template for more distant star-clusters. E-Merlin - the heavily upgraded Merlin radio telescope network - will have greatly improved sensitivity at Gigahertz frequencies and allow us to survey the cluster in unprecedented detail. Associated multiwavelength studies, in the X-ray, optical and IR will add to our view of the cluster.

Specific tasks will include involvement in the E-Merlin data analysis as well as multiwavelength data (probably with a focus on X-ray data from the Chandra satellite as well as lower frequency GMRT data). The scientific focus will be on understanding emission from the numerous colliding wind systems that will be covered in the survey, to understand the nature and the origin of the non-thermal radio emission. Related to this we will also undertake theoretical calculations of the colliding wind phenomenon in support of the observations.

The COBRaS project involves about 30 scientists in the UK, USA, Canada, Belgium, Italy, India and Ireland and this project will involve participation in team meetings as well as likely observing trips to obtain additional data.

For more information please contact Dr. Ian Stevens (Email: irs[at]star.sr.bham.ac.uk)

2) Massive Stars, Star-formation and Star-Clusters in Nearby Galaxies

This Ph.D project will involve working on the upcoming LeMMINGS (Legacy E-Merlin Multi-band Imaging of a complete Nearby Galaxy Sample) survey.

E-Merlin represents a major upgrade to the Merlin radio telescope network, and will provide extremely high resolution and very deep images of the radio sky. The LeMMINGS survey aims to provide the "definitive microJansky sensitivity radio images of a large sample of nearby galaxies". It will do this by observing around 40 nearby (within 20 Mpc) galaxies in a deep survey (and rather more in a shallower survey). These galaxies will consist of all types, from small dwarf galaxies, to larger elliptical and spiral galaxies.

The overall goals of this project are to understand the processes of star-formation and accretion (such as from black-holes) in nearby galaxies. Radio observations suffer much less from obscuration, which is a major issue at optical wavelengths and hence can provide a much more complete census of the contents of galaxies.

This particular Ph.D project will likely focus on two main areas with LeMMINGS, namely radio emission from young massive star-clusters and star-formation regions (including emission from the extreme super stars clusters) and also radio emission from ultraluminous X-ray sources (ULXs). The nature of these objects is still unclear, but they are mostly related to regions of star-formation and massive stars - they could be a new class of intermediate mass black-hole (objects with a mass intermediate between that of stellar mass black-holes such as Cyg X-1 and the massive black-holes in the centres of galaxies) or extreme X-ray binaries where the emission is highly beamed. The higher resolution and sensitivity of E-Merlin will help to answer questions about their nature.

The student will be involved in basic data analysis of the E-Merlin data as well as detailed studies of individual objects or classes of objects. The student could also be involved with some early science verification and/or commissioning observations with e-MERLIN.

The LeMMINGS teams consists of around 40 scientists from the UK, USA, Germany, France, Holland, Spain, Sweden, Chile, India and Australia. This project will involve participation in team meetings as well as likely observing trips to obtain additional data on the sample.

For more information please contact Dr. Ian Stevens (Email: irs[at]star.sr.bham.ac.uk)