Article

Ameliorating systematic uncertainties in the angular clustering of galaxies: a study using the SDSS-III

A.J. RossInstitute of Cosmology & Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FXShirley HoLawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USAAntonio J. CuestaYale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06511, USARita TojeiroInstitute of Cosmology & Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FXWill J. PercivalInstitute of Cosmology & Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FXDavid A. WakeYale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06511, USAKaren L. MastersInstitute of Cosmology & Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FXRobert C. NicholSEPnet, South East Physics Network (http://www.sepnet.ac.uk)Adam D. MyersDepartment of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USAF. de SimoniObservatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, BrazilHee‐Jong SeoBerkeley Center for Cosmological Physics, LBL and Department of Physics, University of California, Berkeley, CA 94720, USAC. Hernández–MonteagudoMax-Planck-Institut für Astrophysik (MPA), Karl Schwarzschild Strasse 1, Garching bei München D-85741, GermanyRobert CrittendenInstitute of Cosmology & Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FXMichael R. BlantonCenter for Cosmology and Particle Physics, New York University, New York, NY 10003, USAJ. BrinkmannL. A. N. da CostaObservatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, BrazilHong GuoDepartment of Astronomy, Case Western Reserve University, Cleveland, OH 44106, USAEyal KazinCenter for Cosmology and Particle Physics, New York University, New York, NY 10003, USAM. A. G. MaiaObservatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, BrazilClaudia MarastonInstitute of Cosmology & Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FXNikhil PadmanabhanYale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06511, USAFrancisco PradaInstituto de Astrofisica de Andalucia (CSIC), Granada, SpainBeatriz RamosLaboratório Interinstitucional de e-Astronomia - LineA, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, BrazilAriel G. SánchezMax-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, 85748 Garching, GermanyEdward F. SchlaflyDepartment of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USADavid J. SchlegelLawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USADonald P. SchneiderDepartment of Astronomy & Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USARamin SkibbaSteward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USAD. ThomasInstitute of Cosmology & Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FXBenjamin A. WeaverCenter for Cosmology and Particle Physics, New York University, New York, NY 10003, USAMartin WhiteDepartment of Astronomy, 601 Campbell Hall, University of California at Berkeley, Berkeley, CA 94720, USAIdit ZehaviDepartment of Astronomy, Case Western Reserve University, Cleveland, OH 44106, USA

2011en

ABI

Abstract

We investigate the effects of potential sources of systematic error on the angular and photometric redshift, zphot, distributions of a sample of redshift 0.4 < z < 0.7 massive galaxies whose selection matches that of the Baryon Oscillation Spectroscopic Survey (BOSS) constant-mass sample. Utilizing over 112 778 BOSS spectra as a training sample, we produce a photometric redshift catalogue for the galaxies in the Sloan Digital Sky Survey eight data release imaging area that, after masking, covers nearly one quarter of the sky (9913 deg^2). We investigate fluctuations in the number density of objects in this sample as a function of Galactic extinction, seeing, stellar density, sky background, airmass, photometric offset and North/South Galactic hemisphere. We find that the presence of stars of comparable magnitudes to our galaxies (which are not traditionally masked) effectively removes area. Failing to correct for such stars can produce systematic errors on the measured angular autocorrelation function, w(θ), that are larger than its statistical uncertainty. We describe how one can effectively mask for the presence of the stars, without removing any galaxies from the sample, and minimize the systematic error. Additionally, we apply two separate methods that can be used to correct for the systematic errors imparted by any parameter that can be turned into a map on the sky. We find that failing to properly account for varying sky background introduces a systematic error on w(θ). We measure w(θ), in four zphot slices of width 0.05 between 0.45 < zphot < 0.65, and find that the measurements, after correcting for the systematic effects of stars and sky background, are generally consistent with a generic Λ cold dark matter model, at scales up to 60°. At scales greater than 3° and zphot > 0.5, the magnitude of the corrections we apply is greater than the statistical uncertainty in w(θ).

Identifiers

DOI: 10.1111/j.1365-2966.2011.19351.x

Citations and references

Cited by 30 references

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