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Euclid: Forecast constraints on the cosmic distance duality relation with complementary external probes

M. Martinelli, C. J. A. P. Martins, S. Nesseris, D. Sapone, I. Tutusaus, A. Avgoustidis, S. Camera, C. Carbone, S. Casas, S. Ilić, Z. Sakr, V. Yankelevich, N. Auricchio, A. Balestra, C. Bodendorf, D. Bonino, E. Branchini, M. Brescia, J. Brinchmann, V. Capobianco, J. Carretero, M. Castellano, S. Cavuoti, R. Clédassou, G. Congedo, L. Conversi, L. Corcione, F. Dubath, A. Ealet, M. Frailis, E. Franceschi, M. Fumana, B. Garilli, B. R. Gillis, C. Giocoli, F. Grupp, S. V. H. Haugan, W. A. Holmes, F. Hormuth, K. Jahnke, S. Kermiche, M. Kilbinger, T. Kitching, B. Kubik, M. Kunz, H. Kurki-Suonio, S. Ligori, P. B. Lilje, I. Lloro, O. Marggraf, K. Markovic, R. Massey, S. Mei, M. Meneghetti, G. Meylan, L. Moscardini, S. Niemi, C. Padilla, S. Paltani, F. Pasian, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. Popa, L. Pozzetti, F. Raison, J. D. Rhodes, M. Roncarelli, R. Saglia, P. Schneider, A. Secroun, S. Serrano, C. Sirignano, G. Sirri, F. Sureau, A. N. Taylor, I. Tereno, R. Toledo-Moreo, L. Valenziano, T. Vassallo, Y. Wang, N Welikala, J. Weller, A. Zacchei

Abstract
Context. In metric theories of gravity with photon number conservation, the luminosity and angular diameter distances are related via the Etherington relation, also known as the distance duality relation (DDR). A violation of this relation would rule out the standard cosmological paradigm and point to the presence of new physics.
Aims. We quantify the ability of Euclid, in combination with contemporary surveys, to improve the current constraints on deviations from the DDR in the redshift range 0 <  z <  1.6.
Methods. We start with an analysis of the latest available data, improving previously reported constraints by a factor of 2.5. We then present a detailed analysis of simulated Euclid and external data products, using both standard parametric methods (relying on phenomenological descriptions of possible DDR violations) and a machine learning reconstruction using genetic algorithms.
Results. We find that for parametric methods Euclid can (in combination with external probes) improve current constraints by approximately a factor of six, while for non-parametric methods Euclid can improve current constraints by a factor of three.
Conclusions. Our results highlight the importance of surveys like Euclid in accurately testing the pillars of the current cosmological paradigm and constraining physics beyond the standard cosmological model.

Keywords
cosmology: observations; cosmological parameters; surveys; methods: data analysis; methods: statistical; space vehicles: instruments; Astrophysics - Cosmology and Nongalactic Astrophysics

Notes
This paper is published on behalf of the Euclid Consortium.

Astronomy and Astrophysics
Volume 644, Article Number A80, Number of pages 13
2020 December

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia