Astronomy Centre

Seb Oliver

Star-Forming Galaxies in the Distant Universe with Herschel and LOFAR

Supervisor: Seb Oliver

Also collaborating with Matt Jarvis, Oxford, and other LOFAR SEPNET partners at Soton and Portsmouth and around UK 

Seb Oliver leads the Herschel Multi-tiered Extra-galactic Survey, Hermes. This is the largest project on ESA's Herschel Space Observatory and has already discovered around hundred thousand distant, dusty, star-forming galaxies (around hundred times as many as were known before Herschel). Your project will use this data to gain a detailed understanding of galaxy evolution around 10 billion years ago. Here we outline one possible project.

A key goal in astrophysics is to understand galaxy formation and evolution. Galaxies today have built up their stellar populations by star-formation and merging. Therefore direct measurements of the star-formation rates in galaxies at high redshift are a key component in advancing our theoretical understanding of those processes. However, at high redshift at least half of the star formation activity is obscured by dust and can only be probed by observations at far infrared (FIR) and radio wavelengths. Such observations are particularly critical for galaxy evolution scenarios. This was notably demonstrated in recent years by the famous discovery by the far infrared instrument SCUBA (and subsequent radio observations) of numerous galaxies with very high star-formation rates that are extremely hard to explain by current models. LOFAR and ESA's Herschel mission were designed for studying these obscured star-forming galaxies at high redshift and high profile survey projects are being carried out by both facilities. The pioneering results from surveys with SCUBA are based on few galaxies over areas of 0.25 sq. degrees. In contrast the Herschel Multi-tiered Extragalactic Survey (HerMES, the largest Herschel program) will map ~70 sq. degrees detecting 100k far infrared galaxies and the LOFAR Deep survey will cover ~80 sq. degrees. These areas are necessary to cover the full range of galaxy environments (from clusters to voids) and to provide statistically significant samples to rigorously test galaxy formation theories. HerMES is coordinated at Sussex by Seb Oliver (in collaboration with Jamie Bock at Caltech) while the LOFAR is a key element of SEPNET Astrophysics Research Theme. These two surveys are closely coordinated in the same regions of the sky since both probe obscured star-formation but through different mechanisms. In addition they are coordinated with a new space-based near infrared survey SERVS and surveys with the new ESO NIR survey telescope VISTA.

This project provides a unique opportunity to exploit these combined data. The objective of the studentship will be (a) to provide LOFAR identifications for the most extreme sub-mm sources, which are candidates for the theory-busting highest redshift and high star-formation rate galaxies (b) to test for evolution in the well-known FIR/radio correlation (c) to exploit this relation to develop a FIR/radio photometric redshift technique for LOFAR/HerMES enabling a variety of other scientific goals.

The plan for the thesis is:
Year 1: Background reading and exposure to HerMES FIR science Learning radio techniques. Extensive participation in LOFAR commissioning.
Year 2: Selection of FIR candidates and analysis of corresponding LOFAR Deep data. Identification and follow-up of prime candidates. Paper(s) on exotic discoveries.
Year 3: Homogenisation of LOFAR and FIR data and exploration of correlations and photo-z techniques. Paper(s) on statistical discoveries & writing up.
This studentship will strongly promote SEPNET collaboration, drawing on the FIR expertise at Sussex and the radio expertise at Soton & Oxford, and the opportunities provided by Sussex coordination of HerMES, SEPNET involvement in LOFAR and Soton/Sussex leadership of SERVS. Primary supervision and FIR analysis training and supervision will be at Sussex. Radio observation training and supervision will be at Oxford and Soton

For more information/to apply for this project, please contact Prof. Seb Oliver (email: S.Oliver [AT]