A1 Refereed original research article in a scientific journal
Euclid preparation LVII. Observational expectations for redshift z < 7 active galactic nuclei in the Euclid Wide and Deep surveys
Authors: Selwood, M.; Fotopoulou, S.; Bremer, M. N.; Bisigello, L.; Landt, H.; Bañados, E.; Zamorani, G.; Shankar, F.; Stern, D.; Lusso, E.; Spinoglio, L.; Allevato, V.; Ricci, F.; Feltre, A.; Mannucci, F.; Salvato, M.; Bowler, R. A. A.; Mignoli, M.; Vergani, D.; La Franca, F.; Amara, A.; Andreon, S.; Auricchio, N.; Baldi, M.; Bardelli, S.; Bender, R.; Bodendorf, C.; Bonino, D.; Branchini, E.; Brescia, M.; Brinchmann, J.; Camera, S.; Capobianco, V.; Carbone, C.; Carretero, J.; Casas, S.; Castellano, M.; Cavuoti, S.; Cimatti, A.; Congedo, G.; Conselice, C. J.; Conversi, L.; Copin, Y.; Courbin, F.; Courtois, H. M.; Cropper, M.; Da Silva, A.; Degaudenzi, H.; Di Giorgio, A. M.; Dinis, J.; Dubath, F.; Dupac, X.; Dusini, S.; Farina, M.; Farrens, S.; Ferriol, S.; Frailis, M.; Franceschi, E.; Galeotta, S.; Gillis, B.; Giocoli, C.; Grazian, A.; Grupp, F.; Guzzo, L.; Haugan, S. V. H.; Hoekstra, H.; Holliman, M. S.; Holmes, W.; Hook, I.; Hormuth, F.; Hornstrup, A.; Hudelot, P.; Jahnke, K.; Keihänen, E.; Kermiche, S.; Kiessling, A.; Kubik, B.; Kümmel, M.; Kunz, M.; Kurki-Suonio, H.; Laureijs, R.; Ligori, S.; Lilje, P. B.; Lindholm, V.; Lloro, I.; Maino, D.; Maiorano, E.; Mansutti, O.; Marggraf, O.; Markovic, K.; Martinet, N.; Marulli, F.; Massey, R.; Medinaceli, E.; Mei, S.; Melchior, M.; Mellier, Y.; Meneghetti, M.; Merlin, E.; Meylan, G.; Moresco, M.; Moscardini, L.; Munari, E.; Niemi, S.-M.; Nightingale, J. W.; Padilla, C.; Paltani, S.; Pasian, F.; Pedersen, K.; Percival, W. J.; Pettorino, V.; Polenta, G.; Poncet, M.; Popa, L. A.; Pozzetti, L.; Raison, F.; Rebolo, R.; Renzi, A.; Rhodes, J.; Riccio, G.; Rix, H.-W.; Romelli, E.; Roncarelli, M.; Rossetti, E.; Saglia, R.; Sapone, D.; Sartoris, B.; Scaramella, R.; Schirmer, M.; Schneider, P.; Schrabback, T.; Scialpi, M.; Secroun, A.; Seidel, G.; Serrano, S.; Sirignano, C.; Sirri, G.; Stanco, L.; Surace, C.; Tallada-Crespí, P.; Tavagnacco, D.; Taylor, A. N.; Teplitz, H. I.; Tereno, I.; Toledo-Moreo, R.; Torradeflot, F.; Tutusaus, I.; Valenziano, L.; Vassallo, T.; Veropalumbo, A.; Wang, Y.; Weller, J.; Zucca, E.; Biviano, A.; Bolzonella, M.; Bozzo, E.; Burigana, C.; Colodro-Conde, C.; De Lucia, G.; Di Ferdinando, D.; Escartin Vigo, J. A.; Farinelli, R.; George, K.; Gracia-Carpio, J.; Martinelli, M.; Mauri, N.; Neissner, C.; Sakr, Z.; Scottez, V.; Tenti, M.; Viel, M.; Wiesmann, M.; Akrami, Y.; Anselmi, S.; Baccigalupi, C.; Ballardini, M.; Bethermin, M.; Blanchard, A.; Blot, L.; Borgani, S.; Bruton, S.; Cabanac, R.; Calabro, A.; Canas-Herrera, G.; Cappi, A.; Carvalho, C. S.; Castignani, G.; Castro, T.; Chambers, K. C.; Contarini, S.; Contini, T.; Cooray, A. R.; Cucciati, O.; Davini, S.; De Caro, B.; Desprez, G.; Díaz-Sánchez, A.; Di Domizio, S.; Dole, H.; Escoffier, S.; Ferrari, A. G.; Ferrero, I.; Finelli, F.; Fontana, A.; Fornari, F.; Gabarra, L.; Ganga, K.; García-Bellido, J.; Gautard, V.; Gaztanaga, E.; Giacomini, F.; Gozaliasl, G.; Hall, A.; Hildebrandt, H.; Hjorth, J.; Kajava, J. J. E.; Kansal, V.; Karagiannis, D.; Kirkpatrick, C. C.; Legrand, L.; Libet, G.; Loureiro, A.; Macias-Perez, J.; Maggio, G.; Magliocchetti, M.; Maoli, R.; Martins, C. J. A. P.; Matthew, S.; Maurin, L.; Metcalf, R. B.; Monaco, P.; Moretti, C.; Morgante, G.; Nadathur, S.; Nicastro, L.; Walton, N. A.; Patrizii, L.; Pezzotta, A.; Pöntinen, M.; Popa, V.; Porciani, C.; Potter, D.; Risso, I.; Rocci, P.-F.; Sahlén, M.; Sánchez, A. G.; Schneider, A.; Sefusatti, E.; Sereno, M.; Simon, P.; Spurio Mancini, A.; Steinwagner, J.; Testera, G.; Teyssier, R.; Toft, S.; Tosi, S.; Troja, A.; Tucci, M.; Valieri, C.; Valiviita, J.; Verza, G.; Weaver, J. R.; Zinchenko, I. A.; Euclid Collaboration
Publisher: EDP Sciences
Publication year: 2025
Journal: Astronomy and Astrophysics
Journal name in source: Astronomy & Astrophysics
Article number: A250
Volume: 693
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202450894
Web address : https://doi.org/10.1051/0004-6361/202450894
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/491416526
We forecast the expected population of active galactic nuclei (AGN) observable in the Euclid Wide Survey (EWS) and Euclid Deep Survey (EDS). Starting from an X-ray luminosity function (XLF), we generated volume-limited samples of the AGN expected in the Euclid survey footprints. Each AGN was assigned a spectral energy distribution (SED) appropriate for its X-ray luminosity and redshift, with perturbations sampled from empirical distributions. The photometric detectability of each AGN was assessed via mock observations of the assigned SED. We estimate 40 million AGN will be detectable in at least one Euclid band in the EWS and 0.24 million in the EDS, corresponding to surface densities of 2.8 × 103 deg-2 and 4.7 × 103 deg-2. The relative uncertainty on our expectation for Euclid detectable AGN is 6.7% for the EWS and 12.5% for the EDS, driven by the uncertainty of the XLF. Employing Euclid-only colour selection criteria on our simulated data we select a sample of 4.8 × 106 (331 deg-2 ) AGN in the EWS and 1.7 × 104 (346 deg-2 ) in the EDS, amounting to 10% and 8% of the AGN detectable in the EWS and EDS. Including ancillary Rubin/LSST bands improves the completeness and purity of AGN selection. These data roughly double the total number of selected AGN to comprise 21% and 15% of the Euclid detectable AGN in the EWS and EDS. The total expected sample of colour-selected AGN contains 6.0 × 106 (74%) unobscured AGN and 2.1 × 106 (26%) obscured AGN, covering 0.02 ≤ z ≲ 5.2 and 43 ≤ log10(Lbol/erg s-1 ) ≤ 47. With these simple colour cuts expected surface densities are already comparable to the yield of modern X-ray and mid-infrared surveys of similar area. The EWS sample is most comparable to the WISE C75 AGN selection and the EDS sample is most similar to the yield of the collated Spitzer cryogenic surveys when considering Euclid bands alone, or the XXL-3XLSS survey AGN sample when also considering selection with ancillary optical bands. We project that 15% (7.6%) of the total Euclid detectable population in the EWS (EDS) will exhibit X-ray fluxes that could be detected in the XMM-COSMOS survey, showing that the vast majority of Euclid-detected AGN would not be detectable in modern medium-depth X-ray surveys.
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We warmly thank the anonymous referee for their detailed comments and excellent suggestions on the manuscript, improving the quality of the work. We also extend our thanks to J. T. Schindler and R. Gilli for their helpful comments and discussion on the manuscript. The Euclid Consortium acknowledges the European Space Agency and a number of agencies and institutes that have supported the development of Euclid, in particular the Agenzia Spaziale Italiana, the Austrian Forschungsförderungsgesellschaft funded through BMK, the Belgian Science Policy, the Canadian Euclid Consortium, the Deutsches Zentrum für Luft- und Raumfahrt, the DTU Space and the Niels Bohr Institute in Denmark, the French Centre National d’Etudes Spatiales, the Fundação para a Ciência e a Tecnologia, the Hungarian Academy of Sciences, the Ministerio de Ciencia, Innovación y Universidades, the National Aeronautics and Space Administration, the National Astronomical Observatory of Japan, the Netherlandse Onderzoekschool Voor Astronomie, the Norwegian Space Agency, the Research Council of Finland, the Romanian Space Agency, the State Secretariat for Education, Research, and Innovation (SERI) at the Swiss Space Office (SSO), and the United Kingdom Space Agency. A complete and detailed list is available on the Euclid web site (http://www.euclid-ec.org). This work is supported by the UKRI AIMLAC CDT, funded by grant EP/S023992/1. This work has benefited from the support of Royal Society Research Grant RGS\R1\231450. V. A., L. B., A. B., G. C., E. L., F. L. F., M. M., F. R. acknowledge the support from the INAF Large Grant “AGN & Euclid: a close entanglement” Ob. Fu. 01.05.23.01.14 VA acknowledges support from INAF-PRIN 1.05.01.85.08 and INAF Large Grant 2023 “AGN and Euclid: a close entanglement”, Ob. Fu. 1.05.23.01.14. A. F. acknowledges the support from project “VLT-MOONS” CRAM 1.05.03.07, INAF Large Grant 2022 “The metal circle: a new sharp view of the baryon cycle up to Cosmic Dawn with the latest generation IFU facilities” and INAF Large Grant 2022 “Dual and binary SMBH in the multi-messenger era”. F. R. and F. L. F. acknowledge support from PRIN 2017 “Black hole winds and the baryon life cycle of galaxies: the stone-guest at the galaxy evolution supper” contract #2017PH3WAT.
