LLAMAS: A Facility Integral Field Spectrograph for the Magellan Telescopes

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Integral field spectroscopy (IFS) is a technique to construct 3D images of the universe analogous to CAT scans or other 3D medical renderings, by optically manipulating the light collected by astronomical telescopes. Using advances in lithographic manufacture of microscopic lenses and fiberoptics, one can sort each light ray entering a telescope according to its position on the sky, and its color -- which physically maps onto a galaxy's velocity (via the Doppler shift) or distance from Earth. The cost of IFS instruments is driven by the large volume of collected data, since their information rate exceeds that of a conventional spectrometer by roughly a hundred-fold. The Large Lenslet Array Magellan Spectrograph (LLAMAS) uses commoditized digital CCD cameras to address this challenge, spectrally imaging a wide field-of-view on the 6.5-meter diameter Magellan Telescopes. LLAMAS will be available to the US astronomical community through an open-access agreement, and will advance studies of explosive astrophysical transients, and the formation and clustering of galaxies. In addition to building LLAMAS, the MIT-based instrument team is partnering with the FabLab maker space of the Somerville, MA Public High School. They will co-teach a telescope-making course that exposes participants to team-based design, optics, and CAD/additive manufacturing methods central to the future engineering economy.LLAMAS is designed for (1) rapid and efficient spectroscopy of astrophysical transients discovered by the Large Synoptic Survey Telescope (LSST), (2) single-pointing redshift and dynamical measurements of galaxy clusters identified by Sunyaev-Zel?dovich surveys of the Southern sky, and (3) single-pointing emission and absorption measurements of Lyman alpha and metal-enriched gas flows within the circumgalactic halos of distant galaxies. It will produce spectral images of a 37" x 37" field of view (scalable to 60" x 60") at 0.75" spatial resolution using 2400 optical fibers. Each fiber produces a spectrum of R=2200 covering the full optical bandpass (350-980 nm) in a single exposure. LLAMAS will be the first seeing-limited, arcminute-class IFS available on a large US telescope. As a permanent facility instrument, it will be available 365 nights per year via rotation of the Magellan tertiary.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.