September
2026
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2026A&A...713A.211E
Authors
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Euclid Collaboration
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Cao, Y.
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Cooray, A. R.
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Li, T.
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Cheng, Y.-T.
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Tanidis, K.
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Lim, S. H.
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Scott, D.
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Altieri, B.
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Amara, A.
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Andreon, S.
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Auricchio, N.
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Baccigalupi, C.
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Baldi, M.
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Bardelli, S.
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Biviano, A.
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Branchini, E.
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Brescia, M.
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Camera, S.
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Cañas-Herrera, G.
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Capobianco, V.
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Carbone, C.
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Carretero, J.
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Casas, S.
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Castellano, M.
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Castignani, G.
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Cavuoti, S.
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Chambers, K. C.
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Cimatti, A.
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Colodro-Conde, C.
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Congedo, G.
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Conselice, C. J.
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Conversi, L.
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Copin, Y.
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Courbin, F.
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Courtois, H. M.
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Cuillandre, J.-C.
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Degaudenzi, H.
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De Lucia, G.
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Dole, H.
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Douspis, M.
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Dubath, F.
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Dupac, X.
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Farina, M.
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Farinelli, R.
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Faustini, F.
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Ferriol, S.
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Finelli, F.
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Frailis, M.
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Franceschi, E.
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Fumana, M.
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Galeotta, S.
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George, K.
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Gillis, B.
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Giocoli, C.
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Gracia-Carpio, J.
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Grazian, A.
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Grupp, F.
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Haugan, S. V. H.
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Holmes, W.
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Hormuth, F.
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Hornstrup, A.
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Jahnke, K.
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Jhabvala, M.
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Joachimi, B.
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Kermiche, S.
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Kiessling, A.
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Kubik, B.
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Kunz, M.
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Kurki-Suonio, H.
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Le Brun, A. M. C.
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Ligori, S.
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Lilje, P. B.
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Lindholm, V.
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Lloro, I.
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Mainetti, G.
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Maino, D.
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Maiorano, E.
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Mansutti, O.
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Marcin, S.
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Marggraf, O.
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Martinelli, M.
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Martinet, N.
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Marulli, F.
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Massey, R. J.
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Medinaceli, E.
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Mei, S.
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Mellier, Y.
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Meneghetti, M.
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Merlin, E.
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Meylan, G.
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Mora, A.
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Moresco, M.
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Moscardini, L.
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Neissner, C.
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Niemi, S.-M.
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Padilla, C.
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Paltani, S.
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Pasian, F.
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Pedersen, K.
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Percival, W. J.
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Pettorino, V.
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Polenta, G.
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Poncet, M.
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Popa, L. A.
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Raison, F.
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Renzi, A.
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Rhodes, J.
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Riccio, G.
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Romelli, E.
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Roncarelli, M.
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Saglia, R.
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Sakr, Z.
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Sapone, D.
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Schneider, P.
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Schrabback, T.
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Secroun, A.
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Seidel, G.
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Serrano, S.
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Sihvola, E.
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Sirignano, C.
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Sirri, G.
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Stanco, L.
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Steinwagner, J.
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Tallada-Crespí, P.
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Tereno, I.
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Tessore, N.
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Toft, S.
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Toledo-Moreo, R.
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Torradeflot, F.
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Tutusaus, I.
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Valenziano, L.
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Valiviita, J.
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Vassallo, T.
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Wang, Y.
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Weller, J.
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Zamorani, G.
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Zerbi, F. M.
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Zucca, E.
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Ballardini, M.
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Bozzo, E.
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Burigana, C.
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Cabanac, R.
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Calabrese, M.
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Cappi, A.
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Castro, T.
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Escartin Vigo, J. A.
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Gabarra, L.
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Macias-Perez, J.
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Maoli, R.
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Martín-Fleitas, J.
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Mauri, N.
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Metcalf, R. B.
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Monaco, P.
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Nucita, A. A.
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Pezzotta, A.
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Pöntinen, M.
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Risso, I.
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Scottez, V.
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Sereno, M.
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Tenti, M.
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Tucci, M.
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Viel, M.
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Wiesmann, M.
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Akrami, Y.
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Andika, I. T.
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Angora, G.
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Anselmi, S.
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Archidiacono, M.
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Aubourg, E.
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Bazzanini, L.
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Bertacca, D.
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Bethermin, M.
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Blanchard, A.
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Blot, L.
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Bonici, M.
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Borgani, S.
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Brown, M. L.
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Bruton, S.
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Calabro, A.
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Camacho Quevedo, B.
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Caro, F.
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Carvalho, C. S.
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Cogato, F.
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Conseil, S.
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Cucciati, O.
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Davini, S.
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Desprez, G.
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Díaz-Sánchez, A.
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Di Domizio, S.
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Diego, J. M.
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Duret, V.
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Elkhashab, M. Y.
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Enia, A.
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Finoguenov, A.
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Fontana, A.
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Franco, A.
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Ganga, K.
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Gasparetto, T.
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Gaztanaga, E.
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Giacomini, F.
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Gianotti, F.
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Gozaliasl, G.
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Gruppuso, A.
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Guidi, M.
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Gutierrez, C. M.
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Hall, A.
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Hernández-Monteagudo, C.
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Hildebrandt, H.
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Hjorth, J.
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Kajava, J. J. E.
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Kang, Y.
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Kansal, V.
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Karagiannis, D.
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Kiiveri, K.
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Kim, J.
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Kirkpatrick, C. C.
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Kruk, S.
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Lattanzi, M.
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Legrand, L.
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Lepori, F.
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Leroy, G.
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Lesci, G. F.
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Lesgourgues, J.
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Liaudat, T. I.
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Liu, S. J.
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Magliocchetti, M.
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Mannucci, F.
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Martins, C. J. A. P.
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Maurin, L.
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Miluzio, M.
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Moretti, C.
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Morgante, G.
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Naidoo, K.
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Natoli, P.
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Navarro-Alsina, A.
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Nesseris, S.
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Pagano, L.
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Paoletti, D.
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Passalacqua, F.
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Paterson, K.
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Patrizii, L.
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Pisani, A.
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Potter, D.
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Pratt, G. W.
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Quai, S.
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Radovich, M.
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Rodighiero, G.
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Rojas, K.
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Roster, W.
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Sacquegna, S.
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Sahlén, M.
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Sanders, D. B.
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Sarpa, E.
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Scarlata, C.
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Schneider, A.
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Sciotti, D.
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Sellentin, E.
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Smith, L. C.
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Sorce, J. G.
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Tarsitano, F.
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Testera, G.
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Teyssier, R.
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Tosi, S.
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Troja, A.
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Venhola, A.
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Vergani, D.
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Verza, G.
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Vinciguerra, S.
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Walton, N. A.
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Weaver, J. R.
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Wright, A. H.
Abstract
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The extragalactic background light (EBL) fluctuations in the optical/near-IR encode the cumulative emission of unresolved galaxies, integrated galaxy light (IGL), diffuse intra-halo light (IHL), and high-z sources from the epoch of reionisation (EoR), but they are difficult to disentangle with auto-spectra alone. Our aim was to decompose the EBL into its principal constituents using multi-band intensity mapping combined with cosmic shear and galaxy clustering. We developed a joint halo-model framework in which IHL follows a mass- and redshift-dependent luminosity scaling, IGL is set by an evolving Schechter luminosity function, and EoR emission is modelled with Pop II/III stellar emissivities and a binned star formation efficiency. Cosmic shear is modelled using the tidal alignment and tidal torquing model for intrinsic alignment. Using mock surveys in a flat Lambda cold dark matter (ΛCDM) cosmology with ten spectral bands spanning 0.75--5.0 μm in the north ecliptic pole deep fields over about 100deg2 with source detections down to AB = 20.5 for masking, and six redshift bins to z = 2.5, we fit auto- and cross-power spectra using a Markov chain Monte Carlo method. The combined SPHEREx × Euclid analysis recovers all fiducial parameters within 1σ and reduces 1σ uncertainties on IHL parameters by 10--30% relative to SPHEREx EBL-only, while EoR star formation efficiency parameters improve by 20--30%. The predicted cross-correlations show a stronger coupling of IHL than IGL to the shear field within adopted model framework, enhancing component separation; conversely, the high-z EoR contribution shows negligible correlation with cosmic shear and galaxy clustering, aiding its isolation in the EBL. Relative to the SPHEREx EBL-only case, the inferred IHL fraction as a function of halo mass is significantly tightened over 1011--1014 M⊙, with uncertainties reduced by 5--30%, and the resulting star formation rate density constraints extend to z ≈ 11, with uncertainty reductions of 15--30%. SPHEREx × Euclid provides a robust systematics-aware route to component-resolved EBL measurements and improved constraints on galaxy formation.
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