Primordial non-Gaussianity from the completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey – I: Catalogue preparation and systematic mitigation
Open Access
- 18 June 2021
- journal article
- research article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 506 (3), 3439-3454
- https://doi.org/10.1093/mnras/stab1730
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 $4699\, {\rm deg}^{2}$. 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.
Funding Information
- Department of Energy
- Office of Science
- High Energy Physics
- National Research Foundation of Korea (2017R1E1A1A01077508, 2020R1A2C1005655)
- Korean Ministry of Education, Science and Technology
This publication has 107 references indexed in Scilit:
- SPECTRAL CLASSIFICATION AND REDSHIFT MEASUREMENT FOR THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEYThe Astronomical Journal, 2012
- Why your model parameter confidences might be too optimistic. Unbiased estimation of the inverse covariance matrixAstronomy & Astrophysics, 2006
- Detection of the Baryon Acoustic Peak in the Large‐Scale Correlation Function of SDSS Luminous Red GalaxiesThe Astrophysical Journal, 2005
- HEALPix: A Framework for High‐Resolution Discretization and Fast Analysis of Data Distributed on the SphereThe Astrophysical Journal, 2005
- Non-Gaussianity in multifield inflationPhysical Review D, 2002
- How to measure CMB power spectra without losing informationPhysical Review D, 1997
- Dependence of density perturbations on the coupling constant in a simple model of inflationPhysical Review D, 1992
- Non-gaussian density perturbations in inflationary cosmologiesPhysics Letters B, 1987
- Dynamics of phase transition in the new inflationary universe scenario and generation of perturbationsPhysics Letters B, 1982
- The development of irregularities in a single bubble inflationary universePhysics Letters B, 1982