Year: 2025
Type: preprint
Abstract: The Euclid survey aims to trace the evolution of cosmic structures up to redshift $z$ $\sim$ 3 and beyond. Its success depends critically on obtaining highly accurate mean redshifts for ensembles of galaxies $n(z)$ in all tomographic bins, essential for deriving robust cosmological constraints. However, photometric redshifts (photo-$z$s) suffer from systematic biases arising from various sources of uncertainty. To address these challenges, we utilised self-organising maps (SOMs) with mock samples resembling the Euclid Wide Survey (EWS), to validate Euclid's uncertainty requirement of $|Δ\langle z \rangle| = \langle z_{\text{est}} \rangle - \langle z \rangle \leq 0.002 (1+z)$ per tomographic bin, assuming DR3-level data. We observe that defining the redshift tomography using the mean spectroscopic redshift (spec-$z$) per SOM cell, results in none of the ten tomographic redshift bins satisfying the requirement. In contrast, the redshift tomography on the photo-$z$s of the EWS-like sample yields superior results, with eight out of ten bins [$0 < z\leq 2.5$] meeting the Euclid requirement. To enhance the realism of our study, we morph our calibration sample to mimic the C3R2 survey in incremental steps. In this context, a maximum of six out of ten bins meet the requirement, strongly advocating the adoption of a redshift tomography defined by the photo-$z$s of individual galaxies rather than the commonly used mean spec-$z$ of SOM cells. To examine the impact on the expected biases for $Ω_{\text{m}}$, $σ_{8}$, and $Δw_{0}$ measured by Euclid, we perform a Fisher forecast for cosmic shear only, based on our redshift uncertainties. Here, we find that even under an evaluation of the uncertainty where the impact of the redshift bias is substantial, most absolute biases remain below 0.1$σ$ in the idealised scenario and below 0.3$σ$ in the more realistic case.
Source: arXiv (Cornell University)
Authors: Roster, W., Wright, A. H., Hildebrandt, H., Reischke, R., Ilbert, O., d’Assignies D., W., Manera, M., Bolzonella, M., Masters, D. C., Paltani, S., Hartley, W. G., Kang, Y., Hoekstra, H., Altieri, B., Amara, A., Andreon, S., Auricchio, N., Baccigalupi, C., Baldi, M., Balestra, A., Bardelli, S., Battaglia, P., Bender, R., Biviano, A., Branchini, E., Brescia, M., Camera, S., Cañas-Herrera, G., Capobianco, V., Carbone, C., Cardone, V. F., Carretero, J., Casas, R., Casas, Santiago, Castander, F. J., Castellano, M., Castignani, G., Cavuoti, S., Chambers, K. C., Cimatti, A., Colodro-Conde, C., Congedo, G., Conselice, C. J., Conversi, L., Copin, Y., Costille, A., Courbin, F., Courtois, H. M., Cropper, M., Da Silva, A., Degaudenzi, H., de la Torre, S., De Lucia, G., Dubath, F., Duncan, C. A. J., Dupac, X., Dusini, S., Escoffier, S., Farina, M., Farinelli, R., Farrens, S., Faustini, F., Ferriol, S., Finelli, F., Fosalba, P., Fourmanoit, N., Frailis, M., Franceschi, E., Fumana, M., Galeotta, S., George, K., Gillard, W., Gillis, B., Giocoli, C., Gracia-Carpio, J., Grazian, A., Grupp, F., Haugan, S. V. H., Holmes, W., Hormuth, F., Hornstrup, A., Hudelot, P., Jahnke, K., Jhabvala, M., Joachimi, B., Keihänen, E., Kermiche, S., Kubik, B., Kurki-Suonio, H., Le Brun, A. M. C., Le Mignant, D., Ligori, S., Lilje, P. B., Lindholm, V., Lloro, I., Maino, D., Maiorano, E., Mansutti, O., Marggraf, O., Martinelli, M., Martinet, N., Marulli, F., Massey, R. J., Medinaceli, E., Mei, S., Melchior, M., Mellier, Y., Meneghetti, M., Merlin, E., Meylan, G., Mora, A., Moresco, M., Moscardini, L., Nakajima, R., Neissner, C., Niemi, S.-M., Padilla, C., Pasian, F., Pedersen, K., Pettorino, V., Pires, S., Polenta, G., Poncet, M., Popa, L. A., Pozzetti, L., Raison, F., Rebolo, R., Renzi, A., Rhodes, J., Riccio, G., Romelli, E., Roncarelli, M., Rosset, C., Rossetti, E., Saglia, R., Sakr, Z., Sapone, D., Sartoris, B., Schirmer, M., Schneider, P., Schrabback, T., Scodeggio, M., Secroun, A., Sefusatti, E., Seidel, G., Serrano, S., Simon, P., Sirignano, C., Sirri, G., Skottfelt, J., Stanco, L., Steinwagner, J., Tallada-Crespí, P., Taylor, A. N., Teplitz, H. I., Tereno, I., Tessore, N., Toft, S., Toledo-Moreo, R., Torradeflot, F., Tutusaus, I., Valenziano, L., Valiviita, J., Vassallo, T., Verdoes Kleijn, G., Veropalumbo, A., Wang, Y., Weller, J., Zamorani, G., Zerbi, F. M., Zucca, E., Burigana, C., Gabarra, L., Porciani, C., Scottez, V., Sereno, M.
Institutions: Laboratoire d’Astrophysique de Marseille, European Space Agency, RWTH Aachen University, Institut de Physique des 2 Infinis de Lyon, Centre de physique des particules de Marseille, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, CEA Paris-Saclay - Etablissement de Saclay, Astrophysique, Instrumentation et Modélisation, CEA Paris-Saclay, Institut d'Astrophysique de Paris, Laboratoire d'Étude de l'Univers et des Phénomènes Extrêmes, Université Paris Diderot, Centre Pierre Binétruy, University of California, Berkeley, Centre National d'Études Spatiales, Institut de Recherche en Astrophysique et Planétologie, Université de Lille
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Aeronautics and Space Administration, European Space Agency, Generalitat de Catalunya, Magyar Tudományos Akadémia, Agenzia Spaziale Italiana, National Astronomical Observatory of Japan, Agenția Spațială Română, Norsk Romsenter, Institut de Física d'Altes Energies, Fundação para a Ciência e a Tecnologia, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Agencia Estatal de Investigación
OpenAlex ID: W4415190836
Cites:
Cited by:
Related to: