Analysing galaxy clustering for future experiments including the Dark Energy Survey

  • Kelly Nock

Student thesis: Doctoral Thesis


The use of Baryon Acoustic Oscillations (BAO) as a standard ruler in the 2-point galaxy clustering signal has proven to be an excellent probe of the cosmological expansion. With the abundance of good quality galaxy data predicted for future large sky surveys, the potential to conduct precision cosmology using clustering analyses is immense. Many of the next generation sky surveys, including the Dark Energy Survey (DES), the Panoramic Survey Telescope and Rapid Response System (PanStarrs), and the Large Synoptic Survey Telescope (LSST), will utilise photometric redshift estimation techniques, which will make it possible to probe wider and deeper regions of the Universe than spectroscopic redshift surveys in an equivalent amount of time. The use of photometric techniques to estimate galaxy redshifts however, induces errors on inferred radial distances. Consequently, the amplitude of the power spectrum and correlation function is reduced in the radial direction by this smoothing. In this regime, precise measurements of the BAO signal will be difficult. Because of this, there is an urgent need to obtain a better understanding of exactly how photometric redshift uncertainties affect 3D clustering analyses, and to investigate alternative clustering analysis techniques that may be used in future experiments.

In this thesis, I investigate the systematic effects arising in the projected correlation function due to redshift-space distortions, and introduce a new binning scheme to eradicate the problem. I also consider the level of systematic uncertainty induced in realistic measurements of the 3D correlation function from conflicting photometric redshift estimation techniques, and highlight a requirement for empirical test results to be incorporated into model predictions of the anisotropic correlation function for future surveys. Finally, I collate my results to make predictions about how BAO can be optimally used in future photometric redshift experiments like the DES.

Date of Award2010
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorWill Percival (Supervisor), Bob Nichol (Supervisor) & Robert Crittenden (Supervisor)

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