THE SDSS-IV EXTENDED BARYON OSCILLATION SPECTROSCOPIC SURVEY: OVERVIEW AND EARLY DATA
Authors: Dawson Kyle S. , Kneib Jean-Paul , Percival Will J. , Alam Shadab , Albareti Franco D. , Anderson Scott F. , Armengaud Eric , Aubourg Éric , Bailey Stephen , Bautista Julian E. , Berlind Andreas A. , Bershady Matthew A. , Beutler Florian , Bizyaev Dmitry , Blanton Michael R. , Blomqvist Michael , Bolton Adam S. , Bovy Jo , Brandt W. N. , Brinkmann Jon , Brownstein Joel R. , Burtin Etienne , Busca N. G. , Cai Zheng , Chuang Chia-Hsun , Clerc Nicolas , Comparat Johan , Cope Frances , Croft Rupert A. C. , Cruz-Gonzalez Irene , Costa Luiz N. da , Cousinou Marie-Claude , Darling Jeremy , Macorra Axel de la , Torre Sylvain de la , Delubac Timothée , Bourboux Hélion du Mas des , Dwelly Tom , Ealet Anne , Eisenstein Daniel J. , Eracleous Michael , Escoffier S. , Fan Xiaohui , Finoguenov Alexis , Font-Ribera Andreu , Frinchaboy Peter , Gaulme Patrick , Georgakakis Antonis , Green Paul , Guo Hong , Guy Julien , Ho Shirley , Holder Diana , Huehnerhoff Joe , Hutchinson Timothy , Jing Yipeng , Jullo Eric , Kamble Vikrant , Kinemuchi Karen , Kirkby David , Kitaura Francisco-Shu , Klaene Mark A. , Laher Russ R. , Lang Dustin , Laurent Pierre , Goff Jean-Marc Le , Li Cheng , Liang Yu , Lima Marcos , Lin Qiufan , Lin Weipeng , Lin Yen-Ting , Long Daniel C. , Lundgren Britt , MacDonald Nicholas , Maia Marcio Antonio Geimba , Malanushenko Elena , Malanushenko Viktor , Mariappan Vivek , McBride Cameron K. , McGreer Ian D. , Ménard Brice , Merloni Andrea , Meza Andres , Montero-Dorta Antonio D. , Muna Demitri , Myers Adam D. , Nandra Kirpal , Naugle Tracy , Newman Jeffrey A. , Noterdaeme Pasquier , Nugent Peter , Ogando Ricardo , Olmstead Matthew D. , Oravetz Audrey , Oravetz Daniel J. , Padmanabhan Nikhil , Palanque-Delabrouille Nathalie , Pan Kaike , Parejko John K. , Pâris Isabelle , Peacock John A. , Petitjean Patrick , Pieri Matthew M. , Pisani Alice , Prada Francisco , Prakash Abhishek , Raichoor Anand , Reid Beth , Rich James , Ridl Jethro , Rodriguez-Torres Sergio , Rosell Aurelio Carnero , Ross Ashley J. , Rossi Graziano , Ruan John , Salvato Mara , Sayres Conor , Schneider Donald P. , Schlegel David J. , Seljak Uros , Seo Hee-Jong , Sesar Branimir , Shandera Sarah , Shu Yiping , Slosar Anže , Sobreira Flavia , Streblyanska Alina , Suzuki Nao , Taylor Donna , Tao Charling , Tinker Jeremy L. , Tojeiro Rita , Vargas-Magaña Mariana , Wang Yuting , Weaver Benjamin A. , Weinberg David H. , White Martin , Wood-Vasey W. M. , Yeche Christophe , Zhai Zhongxu , Zhao Cheng , Zhao Gong-bo , Zheng Zheng , Zhu Guangtun Ben , Zou Hu 
Published: February 2016

In a six-year program started in 2014 July, the Extended Baryon Oscillation Spectroscopic Survey (eBOSS) will conduct novel cosmological observations using the BOSS spectrograph at Apache Point Observatory. These observations will be conducted simultaneously with the Time Domain Spectroscopic Survey (TDSS) designed for variability studies and the Spectroscopic Identification of eROSITA Sources (SPIDERS) program designed for studies of X-ray sources. In particular, eBOSS will measure with percent-level precision the distance-redshift relation with baryon acoustic oscillations (BAO) in the clustering of matter. eBOSS will use four different tracers of the underlying matter density field to vastly expand the volume covered by BOSS and map the large-scale-structures over the relatively unconstrained redshift range 0.6 < z < 2.2. Using more than 250,000 new, spectroscopically confirmed luminous red galaxies at a median redshift z = 0.72, we project that eBOSS will yield measurements of the angular diameter distance d

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(z) to an accuracy of 1.2% and measurements of H(z) to 2.1% when combined with the z > 0.6 sample of BOSS galaxies. With ∼195,000 new emission line galaxy redshifts, we expect BAO measurements of d

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(z) to an accuracy of 3.1% and H(z) to 4.7% at an effective redshift of z = 0.87. A sample of more than 500,000 spectroscopically confirmed quasars will provide the first BAO distance measurements over the redshift range 0.9 < z < 2.2, with expected precision of 2.8% and 4.2% on d

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(z) and H(z), respectively. Finally, with 60,000 new quasars and re-observation of 60,000 BOSS quasars, we will obtain new Lyα forest measurements at redshifts z > 2.1; these new data will enhance the precision of d

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(z) and H(z) at z > 2.1 by a factor of 1.44 relative to BOSS. Furthermore, eBOSS will provide improved tests of General Relativity on cosmological scales through redshift-space distortion measurements, improved tests for non-Gaussianity in the primordial density field, and new constraints on the summed mass of all neutrino species. Here, we provide an overview of the cosmological goals, spectroscopic target sample, demonstration of spectral quality from early data, and projected cosmological constraints from eBOSS.