Euclid preparation. The impact of relativistic redshift-space distortions on two-point clustering statistics from the Euclid wide spectroscopic survey

• Main Authors: Euclid Collaboration, Amara, A, Auricchio, N, Baldi, M, Bonino, D, Brescia, M, Brinchmann, J, Camera, S, Capobianco, V, Carbone, C, Cardone, V. F, Cimatti, A, Copin, Y, Courtois, H. M, Da Silva, A, Degaudenzi, H, Di Giorgio, A. M, Duncan, C. A. J, Dupac, X, Farrens, S, Gómez-Alvarez, P, Haugan, S. V. H, Hormuth, F, Jahnke, K, Joachimi, B, Kermiche, S, Kiessling, A, Kilbinger, M, Kubik, B, Kümmel, M, Kunz, M, Kurki-Suonio, H, Ligori, S, Lilje, P. B, Lloro, I, Mansutti, O, Marggraf, O, Markovic, K, Marulli, F, Medinaceli, E, Mellier, Y, Meylan, G, Pedersen, K, Popa, L. A, Raison, F, Roncarelli, M, Sánchez, A. G, Schneider, P, Schrabback, T, Scodeggio, M, Secroun, A, Seidel, G, Stanco, L, Steinwagner, J, Taylor, A. N, Veropalumbo, A, Wang, Y, Weller, J, Zucca, E, Biviano, A, Calabrese, M, Di Ferdinando, D, Farinelli, R, Gracia-Carpio, J, Akrami, Y, Anselmi, S, Ballardini, M, Blot, L, Böhringer, H, Borgani, S, Bruton, S, Cabanac, R, Carvalho, C. S, Castro, T, de la Torre, S, Díaz-Sánchez, A, Diaz, J. J, Escoffier, S, Ferrero, I, Finoguenov, A, Gozaliasl, G, Hildebrandt, H, Hjorth, J, Karagiannis, D, Lacasa, F, Loureiro, A, Magliocchetti, M, Mannucci, F, Maurin, L, Monaco, P, Walton, Nicholas A, Sahlén, M, Schneider, A, Sereno, M, Mancini, A. Spurio, Tanidis, K, Tosi, S, Vergani, D, Verza, G, Hernández-Monteagudo, C
• Format: Journal Article
• Language: English
• Published: 01-10-2024
• Subjects: Physics - Cosmology and Nongalactic Astrophysics
• DOI: 10.48550/arxiv.2410.00956

Measurements of galaxy clustering are affected by RSD. Peculiar velocities,
gravitational lensing, and other light-cone projection effects modify the
observed redshifts, fluxes, and sky positions of distant light sources. We
determine which of these effects leave a detectable imprint on several 2-point
clustering statistics extracted from the EWSS on large scales. We generate 140
mock galaxy catalogues with the survey geometry and selection function of the
EWSS and make use of the LIGER method to account for a variable number of
relativistic RSD to linear order in the cosmological perturbations. We estimate
different 2-point clustering statistics from the mocks and use the
likelihood-ratio test to calculate the statistical significance with which the
EWSS could reject the null hypothesis that certain relativistic projection
effects can be neglected in the theoretical models. We find that the combined
effects of lensing magnification and convergence imprint characteristic
signatures on several clustering observables. Their S/N ranges between 2.5 and
6 (depending on the adopted summary statistic) for the highest-redshift
galaxies in the EWSS. The corresponding feature due to the peculiar velocity of
the Sun is measured with a S/N of order one or two. The $P_{\ell}(k)$ from the
catalogues that include all relativistic effects reject the null hypothesis
that RSD are only generated by the variation of the peculiar velocity along the
line of sight with a significance of 2.9 standard deviations. As a byproduct of
our study, we demonstrate that the mixing-matrix formalism to model
finite-volume effects in the $P_{\ell}(k)$ can be robustly applied to surveys
made of several disconnected patches. Our results indicate that relativistic
RSD, the contribution from weak gravitational lensing in particular, cannot be
disregarded when modelling 2-point clustering statistics extracted from the
EWSS.