Primordial non-Gaussianity from the completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey - I: Catalogue preparation and systematic mitigation

Mehdi Rezaie, Ashley J. Ross, Hee Jong Seo, Eva Maria Mueller, Will J. Percival, Grant Merz, Reza Katebi, Razvan C. Bunescu, Julian Bautista, Joel R. Brownstein, Etienne Burtin, Kyle Dawson, Héctor Gil-Marín, Jiamin Hou, Eleanor B. Lyke, Axel De La MacOrra, Graziano Rossi, Donald P. Schneider, Pauline Zarrouk, Gong Bo Zhao

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate the large-scale clustering of the final spectroscopic sample of quasars from the recently completed extended Baryon Oscillation Spectroscopic Survey (eBOSS). The sample contains 343 708 objects in the redshift range 0.8 < z < 2.2 and 72 667 objects with redshifts 2.2 < z < 3.5, covering an effective area of 4699, deg2. We develop a neural network-based approach to mitigate spurious fluctuations in the density field caused by spatial variations in the quality of the imaging data used to select targets for follow-up spectroscopy. Simulations are used with the same angular and radial distributions as the real data to estimate covariance matrices, perform error analyses, and assess residual systematic uncertainties. We measure the mean density contrast and cross-correlations of the eBOSS quasars against maps of potential sources of imaging systematics to address algorithm effectiveness, finding that the neural network-based approach outperforms standard linear regression. Stellar density is one of the most important sources of spurious fluctuations, and a new template constructed using data from the Gaia spacecraft provides the best match to the observed quasar clustering. The end-product from this work is a new value-added quasar catalogue with the improved weights to correct for non-linear imaging systematic effects, which will be made public. Our quasar catalogue is used to measure the local-type primordial non-Gaussianity in a companion paper.

Original languageEnglish (US)
Pages (from-to)3439-3454
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume506
Issue number3
DOIs
StatePublished - Sep 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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