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Clustering of quasars in SDSS-IV eBOSS: study of potential systematics and bias determination

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Pierre Laurent, Sarah Eftekharzadeh, Jean-Marc Le Goff, Adam Myers, Etienne Burtin, Martin White, Ashley J. Ross, Jeremy Tinker, Rita Tojeiro, Julian Bautista, Jonathan Brinkmann, Johan Comparat, Kyle Dawson, Hélion du Mas des Bourboux, Jean-Paul Kneib, Ian D. McGreer, Nathalie Palanque-Delabrouille, Will J. Percival, Francisco Prada, Graziano Rossi & 5 more Donald P. Schneider, David Weinberg, Christophe Yèche, Pauline Zarrouk, Gong-Bo Zhao

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We study the first year of the eBOSS quasar sample in the redshift range 0.9<z<2.2 which includes 68,772 homogeneously selected quasars. We show that the main source of systematics in the evaluation of the correlation function arises from inhomogeneities in the quasar target selection, particularly related to the extinction and depth of the imaging data used for targeting. We propose a weighting scheme that mitigates these systematics. We measure the quasar correlation function and provide the most accurate measurement to date of the quasar bias in this redshift range, bQ = 2.45 ± 0.05 at bar_z=1.55, together with its evolution with redshift. We use this information to determine the minimum mass of the halo hosting the quasars and the characteristic halo mass, which we find to be both independent of redshift within statistical error. Using a recently-measured quasar-luminosity-function we also determine the quasar duty cycle. The size of this first year sample is insufficient to detect any luminosity dependence to quasar clustering and this issue should be further studied with the final ~500,000 eBOSS quasar sample.


Original languageEnglish
Article number017
Number of pages28
JournalJournal of Cosmology and Astroparticle Physics
Early online date11 Jul 2017
Publication statusPublished - Jul 2017

    Research areas

  • Galaxy clustering, Redshift surveys, Cosmological parameters from LSS

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