학술논문
Overview of the Instrumentation for the Dark Energy Spectroscopic Instrument
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article
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Abareshi, B; Aguilar, J; Ahlen, S; Alam, Shadab; Alexander, David M; Alfarsy, R; Allen, L; Prieto, C Allende; Alves, O; Ameel, J; Armengaud, E; Asorey, J; Aviles, Alejandro; Bailey, S; Balaguera-Antolínez, A; Ballester, O; Baltay, C; Bault, A; Beltran, SF; Benavides, B; BenZvi, S; Berti, A; Besuner, R; Beutler, Florian; Bianchi, D; Blake, C; Blanc, P; Blum, R; Bolton, A; Bose, S; Bramall, D; Brieden, S; Brodzeller, A; Brooks, D; Brownewell, C; Buckley-Geer, E; Cahn, RN; Cai, Z; Canning, R; Rosell, A Carnero; Carton, P; Casas, R; Castander, FJ; Cervantes-Cota, JL; Chabanier, S; Chaussidon, E; Chuang, C; Circosta, C; Cole, S; Cooper, AP; Costa, L da; Cousinou, M-C; Cuceu, A; Davis, TM; Dawson, K; Cruz-Noriega, R de la; Macorra, A de la; Mattia, A de; Costa, J Della; Demmer, P; Derwent, M; Dey, A; Dey, B; Dhungana, G; Ding, Z; Dobson, C; Doel, P; Donald-McCann, J; Donaldson, J; Douglass, K; Duan, Y; Dunlop, P; Edelstein, J; Eftekharzadeh, S; Eisenstein, DJ; Enriquez-Vargas, M; Escoffier, S; Evatt, M; Fagrelius, P; Fan, X; Fanning, K; Fawcett, VA; Ferraro, S; Ereza, J; Flaugher, B; Font-Ribera, A; Forero-Romero, JE; Frenk, CS; Fromenteau, S; Gänsicke, BT; Garcia-Quintero, C; Garrison, L; Gaztañaga, E; Gerardi, F; Gil-Marín, H; Gontcho, S Gontcho A; Gonzalez-Morales, Alma X; Gonzalez-de-Rivera, G; Gonzalez-Perez, V; Gordon, C
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Abstract
The Dark Energy Spectroscopic Instrument (DESI) has embarked on an ambitiousfive-year survey to explore the nature of dark energy with spectroscopy of 40million galaxies and quasars. DESI will determine precise redshifts and employthe Baryon Acoustic Oscillation method to measure distances from the nearbyuniverse to z > 3.5, as well as measure the growth of structure and probepotential modifications to general relativity. In this paper we describe thesignificant instrumentation we developed for the DESI survey. The newinstrumentation includes a wide-field, 3.2-deg diameter prime-focus correctorthat focuses the light onto 5020 robotic fiber positioners on the 0.812 mdiameter, aspheric focal surface. The positioners and their fibers are dividedamong ten wedge-shaped petals. Each petal is connected to one of tenspectrographs via a contiguous, high-efficiency, nearly 50 m fiber cablebundle. The ten spectrographs each use a pair of dichroics to split the lightinto three channels that together record the light from 360 - 980 nm with aresolution of 2000 to 5000. We describe the science requirements, technicalrequirements on the instrumentation, and management of the project. DESI wasinstalled at the 4-m Mayall telescope at Kitt Peak, and we also describe thefacility upgrades to prepare for DESI and the installation and functionalverification process. DESI has achieved all of its performance goals, and theDESI survey began in May 2021. Some performance highlights include RMSpositioner accuracy better than 0.1", SNR per \sqrt{\AA} > 0.5 for a z > 2quasar with flux 0.28e-17 erg/s/cm^2/A at 380 nm in 4000s, and median SNR = 7of the [OII] doublet at 8e-17 erg/s/cm^2 in a 1000s exposure for emission linegalaxies at z = 1.4 - 1.6. We conclude with highlights from the on-skyvalidation and commissioning of the instrument, key successes, and lessonslearned. (abridged)