The clustering of galaxies in the SDSS-III DR9 Baryon Oscillation Spectroscopic Survey: constraints on primordial non-Gaussianity

Creators: Ross, Ashley J.; Raccanelli, Alvise

Abstract

We analyse the density field of 264 283 galaxies observed by the Sloan Digital Sky Surve (SDSS)-III Baryon Oscillation Spectroscopic Survey (BOSS) and included in the SDSS Data Release 9 (DR9). In total, the SDSS DR9 BOSS data include spectroscopic redshifts for over 400 000 galaxies spread over a footprint of more than 3000 deg^2. We measure the power spectrum of these galaxies with redshifts 0.43 < z < 0.7 in order to constrain the amount of local non-Gaussianity, f^(local)_(NL), in the primordial density field, paying particular attention to the impact of systematic uncertainties. The BOSS galaxy density field is systematically affected by the local stellar density and this influences the ability to accurately measure f^(local)_(NL) . In the absence of any correction, we find (erroneously) that the probability that f^(local)_(NL) is greater than zero, P(f^(local)_(NL) > 0), is 99.5 per cent. After quantifying and correcting for the systematic bias and including the added uncertainty, we find −45 < f^(local)_(NL) < 195 at 95 per cent confidence and P(f^(local)_(NL) > 0) = 91.0 per cent. A more conservative approach assumes that we have only learnt the k dependence of the systematic bias and allows any amplitude for the systematic correction; we find that the systematic effect is not fully degenerate with that of f^(local)_(NL) , and we determine that −82 < f^(local)_(NL) < 178 (at 95 per cent confidence) and P(f^(local)_(NL) > 0) = 68 per cent. This analysis demonstrates the importance of accounting for the impact of Galactic foregrounds on f^(local)_(NL) measurements. We outline the methods that account for these systematic biases and uncertainties. We expect our methods to yield robust constraints on f^(local)_(NL) for both our own and future large-scale structure investigations.

Additional Information

© 2012 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2012 September 27. Received 2012 September 27; in original form 2012 August 7. First published online: November 7, 2012. We thank the anonymous referee for comments that helped improve this paper. AJR is grateful to the UK Science and Technology Facilities Council for financial support through the grant ST/I001204/1. WJP is grateful for support from the UK Science and Technology Facilities Research Council and the European Research Council. Part of the research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation and the US Department of Energy Office of Science. The SDSS-III website is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Cambridge University, Carnegie Mellon University, Case Western University, University of Florida, Fermilab, the French Participation Group, the German Participation Group, Harvard University, UC Irvine, Instituto de Astrofisica de Andalucia, Instituto de Astrofisica de Canarias, Institucio Catalana de Recerca y Estudis Avancat, Barcelona, Instituto de Fisica Corpuscular, theMichigan State/Notre Dame/JINAParticipation Group, Johns Hopkins University, Korean Institute for Advanced Study, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Pittburgh, University of Portsmouth, Princeton University, UC Santa Cruz, the Spanish Participation Group, Texas Christian University, Trieste Astrophysical Observatory, University of Tokyo/IPMU, University of Utah, Vanderbilt University, University of Virginia, University of Washington, University of Wisconson and Yale University.

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Published - MNRAS-2013-Ross-1116-27.pdf

Submitted - 1208.1491v3.pdf

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