AUSTRALIS

Abstract

An Australian consortium of astronomers and engineers (based at AAO, MSSSO and UNSW) were contracted by the European Southern Observatory to carry out a one-year concept design study for a near-infrared multi-object spectrograph for the VLT. The primary scientific motivation for this instrument was the detection and study of highredshift galaxies. The scope of the study included the elucidation of the main science drivers and the development of a VLT instrumentation strategy best suited to those goals. The underlying instrumental philosophy was to supply a significant object multiplex at a high enough spectral resolution to resolve the internal kinematics of galaxies. This science-driven goal also permitted digital OH skysuppression, yielding better S/N and spectral coverage than at lower resolutions. A full contiguous wavelength coverage from 0.9pm to 1.8pm is achieved through the use of multiple HgCdTe-based.spectrograph cameras. A preliminary optical design for the spectrographs has been achieved as has a detailed concept design for the 400-fibre positioner and multiple integral field units. With these capabilities, the proposed instrument is highly effective both for statistical studies of large numbers of objects and detailed studies of individual objects. In addition, the development of a novel fibre optic switching facility permits simultaneous wavelength coverage over the entire optical and near-infrared windows (from 0.45pm to 1.8pm) by the use of dichroics and additional CCD-based spectrographs. The very broad range of science that can be carried out with AUSTRALIS spans fields as diverse as galaxy evolution and large-scale structure, the detection of primeval galaxies, the spatially-resolved kinematics of nearby AGN and star-forming regions, globular cluster dynamics and follow-ups to all-sky surveys. Show more