<i>Euclid </i>preparation: LXXXIV. The flat-sky approximation for the clustering of Euclid's photometric galaxies

Article Article scientifique Article <i>Euclid </i>preparation: LXXXIV. The flat-sky approximation for the clustering of Euclid's photometric galaxies eng 2026-03-17 2026 Euclid Collaboration collaborator Matthewson William Luke 0000-0001-6957-772X Geneva U., Dept. Theor. Phys. 927273 collaborator Durrer Ruth 0000-0001-9833-2086 Geneva U., Dept. Theor. Phys. 106998 Département de physique théorique (FITEO) collaborator Degaudenzi Hubert U. Geneva (main) 775183 Département d'astronomie (ASTRO) collaborator Dubath Florian U. Geneva (main) 507339 Département d'astronomie (ASTRO) collaborator Kunz Martin Geneva U., Dept. Theor. Phys. 109032 Département de physique théorique (FITEO) collaborator Paltani Stéphane U. Geneva (main) 27695 Département d'astronomie (ASTRO) A234 10.1051/0004-6361/202557773 0004-6361 2510.17592 https://www.aanda.org/10.1051/0004-6361/202557773 We compare the performance of the flat-sky approximation and Limber approximation for the clustering analysis of the photometric galaxy catalogue of Euclid. We study a 6 bin configuration representing the first data release (DR1) and a 13 bin configuration representative of the third and final data release (DR3). We find that the Limber approximation is sufficiently accurate for the analysis of the wide bins of DR1. Contrarily, the 13 bins of DR3 cannot be modelled accurately with the Limber approximation. Instead, the flat-sky approximation is accurate to below $5\%$ in recovering the angular power spectra of galaxy number counts in both cases and can be used to simplify the computation of the full power spectrum in harmonic space for the data analysis of DR3. Methods: numerical Cosmology: observations Cosmology: theory Large-scale structure of Universe Dewey 520 Dewey 500.2 37 Département de physique théorique 133 26 Département d'astronomie 12 false Astronomy & astrophysics 707 6b3616de-db4c-4bfe-bb97-c455023c0034 Article (Published version) Public Article_scientifique_from_crossref.pdf 3252431 application/pdf CC BY-4.0 00cfc2e748a8c6198bcd190aab8e7f35603fb34812097442e565c8f3934f48ba openAccess Faculté des sciences / Section de physique / Département de physique théorique Faculté des sciences / Département d'astronomie

Title	Published in	Year	Views	Downloads

Euclid preparation: LXXXIV. The flat-sky approximation for the clustering of Euclid's photometric galaxies	Astronomy & astrophysics	2026	6	9
New Angles: Investigations of the Angular Power Spectrum of Galaxy Number Counts		2023	307	196

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Matthewson, William

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