UC Berkeley UC Berkeley Previously Published Works Title The DESI Experiment Part I: Science,Targeting, and Survey Design Permalink https://escholarship.org/uc/item/2nz5q3bt Authors Collaboration, DESI Aghamousa, Amir Aguilar, Jessica et al. Publication Date 2016-10-31 Peer reviewed eScholarship.org Powered by the California Digital Library University of California The DESI Experiment Part I: Science,Targeting, and Survey Design DESI Collaboration: Amir Aghamousa73, Jessica Aguilar76, Steve Ahlen85, Shadab Alam41;59, Lori E. Allen81, Carlos Allende Prieto64, James Annis52, Stephen Bailey76, Christophe Balland88, Otger Ballester57, Charles Baltay84, Lucas Beaufore45, Chris Bebek76, Timothy C. Beers39, Eric F. Bell28, Jos Luis Bernal66, Robert Besuner89, Florian Beutler62, Chris Blake15, Hannes Bleuler50, Michael Blomqvist2, Robert Blum81, Adam S. Bolton35;81, Cesar Briceno18, David Brooks33, Joel R. Brownstein35, Elizabeth Buckley-Geer52, Angela Burden9, Etienne Burtin12, Nicolas G. Busca7, Robert N. Cahn76, Yan-Chuan Cai59, Laia Cardiel-Sas57, Raymond G. Carlberg23, Pierre-Henri Carton12, Ricard Casas56, Francisco J. Castander56, Jorge L. Cervantes-Cota11, Todd M. Claybaugh76, Madeline Close14, Carl T. Coker26, Shaun Cole60, Johan Comparat67, Andrew P. Cooper60, M.-C. Cousinou4, Martin Crocce56, Jean-Gabriel Cuby2, Daniel P. Cunningham1, Tamara M. Davis86, Kyle S. Dawson35, Axel de la Macorra68, Juan De Vicente19, Timoth´eeDelubac74, Mark Derwent26, Arjun Dey81, Govinda Dhungana44, Zhejie Ding31, Peter Doel33, Yutong T. Duan85, Anne Ealet4, Jerry Edelstein89, Sarah Eftekharzadeh32, Daniel J. Eisenstein53, Ann Elliott45, St´ephanieEscoffier4, Matthew Evatt81, Parker Fagrelius76, Xiaohui Fan90, Kevin Fanning48, Arya Farahi40, Jay Farihi33, Ginevra Favole51;67, Yu Feng47, Enrique Fernandez57, Joseph R. Findlay32, Douglas P. Finkbeiner53, Michael J. Fitzpatrick81, Brenna Flaugher52, Samuel Flender8, Andreu Font-Ribera76, Jaime E. Forero-Romero22, Pablo Fosalba56, Carlos S. Frenk60, Michele Fumagalli16;60, Boris T. Gaensicke49, Giuseppe Gallo52, Juan Garcia-Bellido67, Enrique Gaztanaga56, Nicola Pietro Gentile Fusillo49, Terry Gerard29, Irena Gershkovich48, Tommaso Giannantonio70;78, Denis Gillet50, Guillermo Gonzalez-de-Rivera54, Violeta Gonzalez-Perez62, Shelby Gott81, Or Graur6;38;53, Gaston Gutierrez52, Julien Guy88, Salman Habib8, Henry Heetderks89, Ian Heetderks89, Katrin Heitmann8, Wojciech A. Hellwing60, David A. Herrera81, Shirley Ho41;47;76, Stephen Holland76, Klaus Honscheid26;45, Eric Huff26, Eric Huff45, Timothy A. Hutchinson35, Dragan Huterer48, Ho Seong Hwang87, Joseph Maria Illa Laguna57, Yuzo Ishikawa89, Dianna Jacobs76, Niall Jeffrey33, Patrick Jelinsky89, Elise Jennings52, Linhua Jiang69, Jorge Jimenez57, Jennifer Johnson26, Richard Joyce81, Eric Jullo2, St´ephanieJuneau12;81, Sami Kama44, Armin Karcher76, Sonia Karkar88, Robert Kehoe44, Noble Kennamer37, Stephen Kent52, Martin Kilbinger12, Alex G. Kim76, David Kirkby37, Theodore Kisner76, Ellie Kitanidis47, Jean-Paul Kneib74, Sergey Koposov61, Eve Kovacs8, Kazuya Koyama62, Anthony Kremin48, Richard Kron52, Luzius Kronig50, Andrea Kueter-Young34, Cedric G. Lacey60, Robin Lafever89, Ofer Lahav33, Andrew Lambert76, Michael Lampton89, Martin Landriau76, Dustin Lang23, Tod R. Lauer81, Jean-Marc Le Goff12, Laurent Le Guillou88, Auguste Le Van Suu3, Jae Hyeon Lee42, Su-Jeong Lee45, Daniela Leitner76, Michael Lesser90, Michael E. Levi76, Benjamin L'Huillier73, Baojiu Li60, Ming Liang81, 52 89 28 76 72 13;45 arXiv:1611.00036v2 [astro-ph.IM] 13 Dec 2016 Huan Lin , Eric Linder , Sarah R. Loebman , Zarija Luki´c , Jun Ma , Niall MacCrann , Christophe Magneville12, Laleh Makarem50, Marc Manera17;33, Christopher J. Manser49, Robert Marshall81, Paul Martini13;26, Richard Massey16, Thomas Matheson81, Jeremy McCauley76, Patrick McDonald76, Ian D. McGreer90, Aaron Meisner76, Nigel Metcalfe60, Timothy N. Miller76, Ramon Miquel55;57, John Moustakas34, Adam Myers32, Milind Naik76, Jeffrey A. Newman30, Robert C. Nichol62, Andrina Nicola58, Luiz Nicolati da Costa75;82, Jundan Nie 72, Gustavo Niz21, Peder Norberg16;60, Brian Nord52, Dara Norman81, Peter Nugent27;76, Thomas O'Brien26, Minji Oh73;93, Knut A. G. Olsen81, Cristobal Padilla57, Hamsa Padmanabhan58, Nikhil Padmanabhan84, Nathalie Palanque-Delabrouille12, Antonella Palmese36, Daniel Pappalardo26, Isabelle Pris2, Changbom Park87, Anna Patej42;90, John A. Peacock59, Hiranya V. Peiris33, Xiyan Peng72, Will J. Percival62, Sandrine Perruchot3, Matthew M. Pieri2, Richard Pogge26, Jennifer E. Pollack62, Claire Poppett89, Francisco Prada63, Abhishek Prakash30, Ronald G. Probst81, David Rabinowitz84, Anand Raichoor12;74, Chang Hee Ree73, Alexandre Refregier58, Xavier Regal3, Beth Reid76, Kevin Reil71, Mehdi Rezaie31, Constance M. Rockosi24;92, Natalie Roe76, Samuel Ronayette3, Aaron Roodman71, Ashley J. Ross13;26, Nicholas P. Ross59, Graziano Rossi25, Eduardo Rozo46, Vanina Ruhlmann-Kleider12, Eli S. Rykoff71, Cristiano Sabiu73, Lado Samushia43, Eusebio Sanchez19, Javier Sanchez37, David J. Schlegel76, Michael Schneider77, Michael Schubnell48, Aurlia Secroun4, Uros Seljak47, Hee-Jong Seo20, Santiago Serrano56, Arman Shafieloo73, Huanyuan Shan74, Ray Sharples14, Michael J. Sholl5, William V. Shourt89, Joseph H. Silber76, David R. Silva81, Martin M. Sirk89, Anze Slosar10, Alex Smith60, George F. Smoot47;76, Debopam Som2, Yong-Seon Song73, David Sprayberry81, Ryan Staten44, Andy Stefanik52, Gregory Tarle48, Suk Sien Tie26, Jeremy L. Tinker38, Rita Tojeiro91, Francisco Valdes81, Octavio Valenzuela65, Monica Valluri28, Mariana Vargas-Magana68, Licia Verde55;66, Alistair R. Walker81, Jiali Wang72, Yuting Wang80, Benjamin A. Weaver38, Curtis Weaverdyck48, Risa H. Wechsler71;83, David H. Weinberg26, Martin White47, Qian Yang69;90, Christophe Yeche12, Tianmeng Zhang72, Gong-Bo Zhao80, Yi Zheng73, Xu Zhou80, Zhimin Zhou80, Yaling Zhu89, Hu Zou72, Ying Zu13;79 (Affiliations can be found after the references) Abstract DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. To trace the underlying dark matter distribution, spectroscopic targets will be selected in four classes from imaging data. We will measure luminous red galaxies up to z = 1:0. To probe the Universe out to even higher redshift, DESI will target bright [O II] emission line galaxies up to z = 1:7. Quasars will be targeted both as direct tracers of the underlying dark matter distribution and, at higher redshifts (2:1 < z < 3:5), for the Ly-α forest absorption features in their spectra, which will be used to trace the distribution of neutral hydrogen. When moonlight prevents efficient observations of the faint targets of the baseline survey, DESI will conduct a magnitude-limited Bright Galaxy Survey comprising approximately 10 million galaxies with a median z 0:2. In total, more than 30 million galaxy and quasar redshifts will be obtained to measure≈ the BAO feature and determine the matter power spectrum, including redshift space distortions. 2 Contents 1 Overview 1 2 Science Motivation and Requirements 3 2.1 Introduction . .3 2.2 Measuring Distances with Baryon Acoustic Oscillations . .6 2.2.1 Theory . .6 2.2.2 BAO in Galaxies . .6 2.2.3 BAO in the Ly-α Forest . .9 2.3 Measuring Growth of Structure with Redshift Space Distortions . 12 2.3.1 Theory . 12 2.3.2 Systematics . 13 2.3.3 Current Status of RSD Measurements . 14 2.4 Distance, Growth, Dark Energy, and Curvature Constraint Forecasts . 17 2.4.1 Forecasting Overview . 17 2.4.2 Baseline Survey . 19 2.4.3 Summary of Forecasts . 21 2.4.4 Forecasting Details . 25 2.5 Cosmology Beyond Dark Energy . 28 2.5.1 Inflation . 28 2.5.2 Neutrinos . 32 2.6 The Milky Way Survey: Near-Field Cosmology from Stellar Spectroscopy . 35 2.7 Complementarity with Other Surveys . 36 2.7.1 Synergies with Planck and Future CMB Experiments . 36 2.7.2 Synergies of DESI with DES and LSST . 36 2.7.3 Synergies of DESI with Euclid/WFIRST .................... 39 3 Target Selection 40 3.1 Targets: Bright Galaxy Sample . 43 3.1.1 Overview of the Sample . 43 3.1.2 Sample Properties . 43 3.2 Targets: Luminous Red Galaxies . 47 3.2.1 Overview of the Sample . 47 3.2.2 Selection Technique for z > 0:6 LRGs . 47 3.2.3 Sample Properties . 49 3.3 Targets: Emission Line Galaxies . 52 3.3.1 Overview of the sample . 52 3.3.2 Selection Technique for z > 0:6 ELGs . 52 3.3.3 Sample Properties . 54 3.4 Targets: QSOs . 58 3.4.1 Overview of the sample . 58 3.4.2 Selection Technique . 59 3.4.3 Sample Properties . 61 3.4.4 Recent and near-term developments for QSO target selection . 63 3.4.5 Variability Data Improves Selection of High-Redshift QSOs . 63 3.5 Calibration Targets . 64 i 3.6 Baseline Imaging Datasets . 65 3.6.1 Blanco/DECam Surveys (DEC 34◦)....................... 65 3.6.2 Bok/90Prime Survey (DEC 34≤◦)......................... 67 3.6.3 Mayall/MOSAIC Survey (DEC≥ 34◦)....................... 68 3.6.4 W ISE All-Sky Survey . .≥ . 68 3.7 Additional Imaging Data . 70 3.7.1 SDSS . 70 3.7.2 PanSTARRS-1 . 70 3.7.3 PTF, iPTF, and ZTF . 70 3.7.4 CFHT . 71 3.7.5 SCUSS . 71 3.8 The Tractor Photometry for Target Selection . 72 4 Survey Design 75 4.1 Introduction . 75 4.2 Survey Footprint . 75 4.3 Field Centers . 75 4.4 Observation Strategy . 78 4.4.1 Sequence of Observations . 78 4.4.2 Exposure Times and Margin . 79 4.5 The Bright Galaxy and Milky Way Surveys . 80 4.5.1 Introduction . 80