Hector - a modular integral field spectrograph instrument for the Anglo-Australian Telescope

摘要

Based on the success of the SAMI integral field spectrograph (IFS) instrument on the Anglo-Australian Telescope (AAT) the capacity for large IFS nearby galaxy surveys on the AAT is being substantially expanded with a new instrument called Hector. The high filling-fraction imaging fibre bundles 'hexabundles' of the type used on SAMI, are being enlarged to cover up to 30-arcsec diameter. The aim is to reach two effective radii on most galaxies, where the galaxy rotation curve flattens and >75% of the specific angular momentum of disk galaxies is accounted for. Driven by the key science case, Hector will have a 1.3A spectral resolution, enabling high-order stellar kinematics to be measured on a larger fraction of galaxies than with any other IFS instrument. Hector will be on sky in 2019. The first module of Hector, Hector-I, will have 21 hexabundles and >42 sky fibres to observe 20 galaxies and a calibration star simultaneously. It consists of new blue and red-arm spectrographs that have been designed at the Australian Astronomical Observatory (AAO; now called AAO-Macquarie), coupled to the new hexabundles and robotic positioner from AAO-USydney (formerly the Sydney Astrophotonics Instrumentation Laboratory, SAIL) at Sydney University. A novel robotic positioning concept will compensate for varying telecentricity over the 2-degree-field of the AAT to recoup the 20% loss in light at the edge of the field. Hector-I will survey 15,000 galaxies. Additional modules in the future would result in 30,000 galaxies. Hector will take integral field spectroscopy on galaxies with z<0.15 in the 4MOST WAVES-North and WAVES-South regions. The WAVES data, which will come later, will give the environment metrics necessary to relate how local and global environments influence galaxy growth through gas accretion, star formation and spins measured with Hector. The WALLABY ASKAP survey will trace HI gas across the Hector fields, which in combination with Hector will give a complete view of gas accretion and star formation.