Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/224987

Title

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

Author(s)

Ross, Ashley J.;  Ho, Shirley;  Cuesta, Antonio J.;  Tojeiro, Rita;  Percival, Will J.;  Wake, David;  Masters, Karen L.;  Nichol, Robert C.;  Myers, Adam D.;  de Simoni, Fernando;  Seo, Hee Jong;  Hernandez-Monteagudo, Carlos;  Crittenden, Robert;  Blanton, Michael;  Brinkmann, J.;  da Costa, Luiz A. N.;  Guo, Hong;  Kazin, Eyal;  Maia, Marcio A. G.;  Maraston, Claudia;  Padmanabhan, Nikhil;  Prada, Francisco;  Ramos, Beatriz;  Sanchez, Ariel;  Schlafly, Edward F.;  Schlegel, David J.;  Schneider, Donald P.;  Skibba, Ramin;  Thomas, Daniel;  Weaver, Benjamin A.;  White, Martin;  Zehavi, Idit

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).

Publication type

Journal article

Source

Monthly Notices of the Royal Astronomical Society, Vol. 417, no. 2 (Oct 2011), pp. 1350-1373

Publication year

2011

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Baryon Oscillation Spectroscopic Survey;  Large-scale structure of Universe;  Statistical methods

Publisher

Wiley-Blackwell

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2011.19351.x

Copyright

Copyright © 2011 The Authors. Journal compilation copyright © 2011 Royal Astronomical Society.

Additional information

The photometric redshift catalogue produced will be made publicly available at http://portal.nersc.gov/project/boss/galaxy/photoz/.

Peer reviewed