CURRENT RESEARCH TOPICS

Large ALMA surveys in the UDS and COSMOS fields

The Atacama Large Millimeter Array (ALMA) is the most powerful sub/millimetre interferometer on the planet. This instrument is capable of mapping the distribution of dust and molecular and atomic gas within distant submillimetre galaxies in exquisite detail. We have used ALMA to survey >1,000 submillimetre galaxies across three square degrees of sky in the well-studied UKIDSS Ultra Deep Survey and COSMOS fields. We have employed these samples to investigate the properties and evolution of this population with samples which are an order of magnitude larger than anything previously available. More details of the results and the projects can be found here.  

ALESS: An ALMA/LABOCA Survey in ECDFS

High-priority ALMA Cycle 0 and Cycle 1 time was awarded to ALESS a project to follow-up submillimetre galaxies identified in the LESS submillimetre survey (see below). The LESS submillimetre map had a spatial resolution of only 18 arcseconds FWHM, which is insufficient to precisely locate the submillimetre counterparts. In contrast, ALMA, even in its most compact configuration, has a resolution of 2 arcseconds, allowing us to precisely locate a large sample of the dust-obscured starbursts occuring in these systems for the first time. The image here shows HST optical images with the ALMA submillimetre emission overlaid as the contours. Thus ALMA provides unambiguous identifications for the submillimetre sources, many of which were previously unidentified. More information on the results from this programme can be found here.  

LESS was an extragalactic submm survey using the LABOCA Camera on the 12-m APEX Telescope. The project mapped the 0.5×0.5 degree Extended Chandra Deep Field South (ECDFS) field at 870um to a depth of ~1.2mJy. The LESS project was allocated 350 hours on LABOCA, with equal contributions from MPI and ESO. The PIs of LESS were: Ian Smail (ESO co-PI), Fabian Walter (ESO co-PI) and Axel Weiss (MPI PI). The survey was a collaboration of around 40 scientists based in Europe and the US and provided the foundation for the ALESS ALMA Cycle 0 survey.

SCUBA-2 Cosmology Legacy Survey

The SCUBA-2 Cosmology Legacy Survey (S2CLS) was a collaboration of ~100 scientists in the UK, Canada and the Netherlands. The survey exploited the immense increase in mapping speed, fidelity and sensitivity of the new SCUBA2 submillimeter camera on the James Clerk Maxwell Telescope in Hawaii. The goal of the survey was to provide the first large samples of extragalactic sources selected in the 450- and 850-um wavebands. These atmospheric windows allowed us to access the redshifted far-infrared emission from luminous but highly, high-redshift galaxies and AGN - pin-pointing an intense era of activity in the early Universe associated with the formation of massive galaxies and black holes. The survey has a simple two-tier design, comprising a wide 850-um component and a deeper 450um survey over a smaller region. The 850-um observations will deliver 1,000's of submillimetre galaxies, allowing the first detailed statistical study of the submillimetre galaxy population. At the same time the survey had the area coverage needed to search for rare sub-classes of submillimetre galaxies (e.g. transition objects) which provide powerful insights into the processes operating within these systems, such as starburst- and AGN-powered feedback, and trace overdensities of submillimetre sources which potentially pin-point the initial collapse of proto-clusters. The very deep 450-um observations enabled us to resolve for the first time the bulk of the extragalactic background light at 450um, as well as providing precise positions sufficient to directly identify the counterparts to these sources in other wavebands. This single co-ordinated survey programme will revolutionize our understanding of submillimetre galaxies, and indeed galaxy formation in general, with enormous and lasting legacy value, as well as providing a springboard for future exploitation of Atacama Millimeter Array (ALMA), Herschel, LOFAR, James Webb Space Telescope (JWST) and the Square Kilometer Array (SKA). Further details and publications can be found here.

HiZELS: The High-Z Emission Line Survey

HiZELS was the first truly panoramic extragalactic narrow-band survey, roughly two-orders of magnitude larger than any similar previous study. The survey uses the WFCAM instrument on the 3.8-m UK Infrared Telescope utilizing a set of existing and custom-made narrow-band filters in the J, H and K-bands to detect emission line galaxies at z = 1-3.5 over ~10 square degrees of extragalactic sky in the UKIDSS DXS survey regions. The survey employed the H2(S1) narrow-band filter to target H-alpha emitting galaxies at z=2.23. In addition, in anticipation of this survey, we purchased specially designed narrow-band filters targeting the [OII] emission line at 3727A and the [OIII] line at 5007A, in galaxies at the same redshift as the H-alpha survey. Together these three sets of filters will enable us to investigate the [OII] 3727, [OIII] 5007 and H-alpha emission from galaxies at z=2.23, while the J- and H-band filters delivers identically-selected H-alpha samples at z=0.84 and 1.47 respectively. The comparisons between the luminosity function, the clustering and variation with environment of these H-alpha-selected samples across z=0.8-2.2 yielded unique constraints on the evolution of star-forming galaxies. The J-band filter is also sensitive to Ly-alpha emission from galaxies at z=8.90 and provided constraints on theoretical predictions of their number density. This survey used 700 hours of time on UKIRT. Further details including all of the papers can be found here.