{"id":{"repo_id":"durham","oai_identifier":"oai:etheses.durham.ac.uk:129"},"canonical_url":"https://search.dev.ndltd.org/etd/durham/oai:etheses.durham.ac.uk:129","repository":{"repo_id":"durham","name":"Durham University","base_url":"http://etheses.dur.ac.uk/cgi/oai2"},"display":{"title":"Constraining dark energy using real and mock galaxy surveys","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Cai, Yanchuan"],"institution":"Durham University","degree_name":"PhD","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2009,"date_issued":"2009","date_published":"2009","updated_at":"2026-07-24T02:11:01Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Cai, Yanchuan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2009"]},{"key":"dc:date.issued","label":"Date","values":["2009"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Physics, Department of"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["Durham University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://etheses.durham.ac.uk/id/eprint/129/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["PhD"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://etheses.durham.ac.uk/id/eprint/129/1/thesis.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Constraining dark energy using real and mock galaxy surveys"]}]}],"canonical_facts":{"dc:creator":["Cai, Yanchuan"],"dc:date":["2009"],"dc:date.issued":["2009"],"dc:description.abstract":["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."],"dc:format":["text"],"dc:identifier.uri":["https://etheses.durham.ac.uk/id/eprint/129/1/thesis.pdf"],"dc:publisher.department":["Physics, Department of"],"dc:publisher.institution":["Durham University"],"dc:relation.isreferencedby":["https://etheses.durham.ac.uk/id/eprint/129/"],"dc:title":["Constraining dark energy using real and mock galaxy surveys"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["PhD"]},"updated_at":"2026-07-24T02:11:01Z"}