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|Title:||Euclid: The importance of galaxy clustering and weak lensing cross-correlations within the photometric Euclid survey||Authors:||Tutusaus, I.
CARDONE, Vincenzo Fabrizio
Castander, F. J.
GARILLI, BIANCA MARIA ROSA
Lilje, P. B.
Percival, W. J.
Taylor, A. N.
|Issue Date:||2020||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||643||First Page:||A70||Abstract:||Context. The data from the Euclid mission will enable the measurement of the angular positions and weak lensing shapes of over a billion galaxies, with their photometric redshifts obtained together with ground-based observations. This large dataset, with well-controlled systematic effects, will allow for cosmological analyses using the angular clustering of galaxies (GCph) and cosmic shear (WL). For Euclid, these two cosmological probes will not be independent because they will probe the same volume of the Universe. The cross-correlation (XC) between these probes can tighten constraints and is therefore important to quantify their impact for Euclid. Aims: In this study, we therefore extend the recently published Euclid forecasts by carefully quantifying the impact of XC not only on the final parameter constraints for different cosmological models, but also on the nuisance parameters. In particular, we aim to decipher the amount of additional information that XC can provide for parameters encoding systematic effects, such as galaxy bias, intrinsic alignments (IAs), and knowledge of the redshift distributions. Methods: We follow the Fisher matrix formalism and make use of previously validated codes. We also investigate a different galaxy bias model, which was obtained from the Flagship simulation, and additional photometric-redshift uncertainties; we also elucidate the impact of including the XC terms on constraining these latter. Results: Starting with a baseline model, we show that the XC terms reduce the uncertainties on galaxy bias by ∼17% and the uncertainties on IA by a factor of about four. The XC terms also help in constraining the γ parameter for minimal modified gravity models. Concerning galaxy bias, we observe that the role of the XC terms on the final parameter constraints is qualitatively the same irrespective of the specific galaxy-bias model used. For IA, we show that the XC terms can help in distinguishing between different models, and that if IA terms are neglected then this can lead to significant biases on the cosmological parameters. Finally, we show that the XC terms can lead to a better determination of the mean of the photometric galaxy distributions. Conclusions: We find that the XC between GCph and WL within the Euclid survey is necessary to extract the full information content from the data in future analyses. These terms help in better constraining the cosmological model, and also lead to a better understanding of the systematic effects that contaminate these probes. Furthermore, we find that XC significantly helps in constraining the mean of the photometric-redshift distributions, but, at the same time, it requires more precise knowledge of this mean with respect to single probes in order not to degrade the final "figure of merit".||Acknowledgments:||This work started in the cross-correlation group, led by A. Blanchard, M. Kunz, and F. Lacasa, of the Inter-Science Working Group Task-force for forecasting of the Euclid Consortium. I. Tutusaus acknowledges support from the Spanish Ministry of Science, Innovation and Universities through grant ESP2017-89838-C3-1-R, and the H2020 programme of the European Commission through grant 776247. M. Martinelli has received the support of a fellowship from “la Caixa” Foundation (ID 100010434), with fellowship code LCF/BQ/PI19/11690015, and the support of the Spanish Agencia Estatal de Investigacion through the grant “IFT Centro de Excelencia Severo Ochoa SEV-2016-0597”. S. Camera acknowledges support from the “Departments of Excellence 20182022” Grant awarded by the Italian Ministry of Education, University and Research (MIUR) L. 232/2016. S. Camera is supported by MIUR through Rita Levi Montalcini project “prometheus – Probing and Relating Observables with Multi-wavelength Experiments To Help Enlightening the Universe’s Structure”. F. Lacasa acknowledges support by the Swiss National Science Foundation. S. Ili´c acknowledges financial support from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013)/ERC Grant Agreement No. 617656 “Theories and Models of the Dark Sector: Dark Matter, Dark Energy and Gravity”. V. Yankelevich acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 769130). P. Ntelis is funded by “Centre National d’Études Spatiales” (CNES), for the Euclid project. The Euclid Consortium acknowledges the European Space Agency and the support of a number of agencies and institutes that have supported the development of Euclid, in particular the Academy of Finland, the Agenzia Spaziale Italiana, the Belgian Science Policy, the Canadian Euclid Consortium, the Centre National d’Etudes Spatiales, the Deutsches Zentrum für Luft- und Raumfahrt, the Danish Space Research Institute, the Fundação para a Ciência e a Tecnologia, the Ministerio de Economia y Competitividad, the National Aeronautics and Space Administration, the Netherlandse Onderzoekschool Voor Astronomie, the Norwegian Space Agency, the Romanian Space Agency, the State Secretariat for Education, Research and Innovation (SERI) at the Swiss Space Office (SSO), and the United Kingdom Space Agency. A detailed complete list is available on the Euclid website (http:// www.euclid-ec.org)||URI:||http://hdl.handle.net/20.500.12386/31472||URL:||https://www.aanda.org/articles/aa/full_html/2020/11/aa38313-20/aa38313-20.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/202038313||Bibcode ADS:||2020A&A...643A..70T||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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