BigBOSS-UK development

BigBOSS is a ground-based dark energy experiment to study the cosmological expansion rate and the growth of structure with a wide-angle spectroscopic galaxy and quasar redshift survey. A wide range of additional science is possible using the 5000 fibre multi-object spectrograph required for this experiment, including studying galaxy formation and evolution, galaxy cluster surveys, the structure of the Milky-Way galaxy and Galactic archeology.

In order to undertake the proposed survey, a US-Europe-China collaboration has come together with the aim of constructing a 5000-fiber spectrograph that will initially deploy on the Mayall 4m-telescope. The key science goals represent a field in which the UK has world leadership and strong scientific interest, built up through STFC support for participation in the 2-degree Field Galaxy Redshift Survey and the Dark Energy Survey.

This grant provides development funding for two key areas of hardware development where the UK has internationally regarded expertise - the optical corrector, and the fibre system, and will retain UK involvement in this ground-breaking project.

Skill development: The development grant, and continuation from joining the full BigBOSS consortium would develop the skills of ~4 technical staff in the UK in the instrumentation area. If the UK provides a full commitment to join BigBOSS, the project will develop the skills of ~10 PhD students mostly in the data processing and data analysis areas.

Fibre system: The massively multiplexed fibre system of BigBOSS provides a significant technical challenge in developing an efficient coupling to the BigBOSS spectrographs. Techniques to be investigated in this study could have wide applicability to spectral image reformatters based on optical fibres and applied in fields as diverse as process inspection and remote diagnostics, where access to the target area is restricted.

Optical system: The BigBOSS optical system comprises of lenses of 0.9-1.25m in diameter that need to be aligned to within tolerances of approximately 100 micrometers. This poses a major challenge to the mounting and alignment of the lenses along with the testing of the complete system. Advances in mounting and alignment of large lenses coupled with large optics production developments at OpTiC, North Wales, give the UK the potential to produce large optical systems for use, for example, in proposed high power laser facilities such as the High Power laser Energy Research facility (HYPER).