Characterizing unknown systematics in large scale structure surveys

Nishant Agarwal, Shirley Ho, Adam D. Myers, Hee Jong Seo, Ashley J. Ross, Neta Bahcall, Jonathan Brinkmann, Daniel J. Eisenstein, Demitri Muna, Nathalie Palanque-Delabrouille, Isabelle Pâris, Patrick Petitjean, Donald P. Schneider, Alina Streblyanska, Benjamin A. Weaver, Christophe Yèche

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Photometric large scale structure (LSS) surveys probe the largest volumes in the Universe, but are inevitably limited by systematic uncertainties. Imperfect photometric calibration leads to biases in our measurements of the density fields of LSS tracers such as galaxies and quasars, and as a result in cosmological parameter estimation. Earlier studies have proposed using cross-correlations between different redshift slices or cross-correlations between different surveys to reduce the effects of such systematics. In this paper we develop a method to characterize unknown systematics. We demonstrate that while we do not have sufficient information to correct for unknown systematics in the data, we can obtain an estimate of their magnitude. We define a parameter to estimate contamination from unknown systematics using cross-correlations between different redshift slices and propose discarding bins in the angular power spectrum that lie outside a certain contamination tolerance level. We show that this method improves estimates of the bias using simulated data and further apply it to photometric luminous red galaxies in the Sloan Digital Sky Survey as a case study.

Original languageEnglish (US)
Article number007
JournalJournal of Cosmology and Astroparticle Physics
Issue number4
StatePublished - Apr 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics


  • Power spectrum
  • cosmological parameters from LSS
  • galaxy surveys
  • redshift surveys


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