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Durham e-Theses
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Constraining dark energy using real and mock galaxy surveys

CAI, YANCHUAN (2009) Constraining dark energy using real and mock galaxy surveys. Doctoral thesis, Durham University.



In this thesis, we study how dark energy may be constrained by measurements of large-scale clustering in future galaxy surveys, and through the imprint of a time-varying large-scale potential on the CMB (the integrated Sachs-Wolfe effect).

We use semi-analytical galaxy formation models implemented in N-body simulations to build mock galaxy catalogues which are well suited for use in conjunction with large photometric surveys. Using mock catalogues, we predict that Pan-STARRS1 will be able to detect 10^8 galaxies in all its 5 photometric bands. We investigate the photo-z performance of the mock survey, which is a crucial factor when measuring large-scale structure statistics from a survey of this kind. We find using Pan-STARRS1 alone, photo-z accuracy of dz/(1+z) ~ 0.06 is achievable. The accuracy can be improved by combining near infrared photometry or by choosing a red galaxy sample. We implemented the photo-z errors to investigate their influence on the detectability of dark energy in the survey via the baryonic acoustic oscillations.

We explore the challenges of using the ISW effect as a constraint on dark energy. In particular, we investigate the effect of non-linear gravitational evolution, using N-body simulations. We have quantified the non-linear contribution to the ISW measurements in terms of both its power spectrum and its cross-correlation with large-scale structure. We have discovered that the non-linear ISW effect is more important relative to the linear ISW effect at larger scales at higher redshifts. This draws attention to the need to accurately model the non-linear effect when using galaxy samples to do ISW tomography at high redshifts. We have developed a ray-tracing method for constructing full sky maps of the ISW effect including its non-linear aspect. Using these maps, we have developed a complete picture of the non-linear ISW effect in void and cluster regions. We quantify the total contribution of the linear and non-linear ISW effects to reported abnormal CMB cold spots and discuss possible confusion with the Sunyaev-Zel'dovich effect.

Item Type:Thesis (Doctoral)
Award:Doctor of Philosophy
Keywords:cosmology; large-scale structure of the Universe; numerical
Faculty and Department:Faculty of Science > Physics, Department of
Thesis Date:2009
Copyright:Copyright of this thesis is held by the author
Deposited On:15 Feb 2010 16:07

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