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arxiv: 2503.15316 · v2 · pith:TONJ7QRLnew · submitted 2025-03-19 · 🌌 astro-ph.GA

Euclid Quick Data Release (Q1). Optical and near-infrared identification and classification of point-like X-ray selected sources

Euclid Collaboration: W. Roster , M. Salvato , J. Buchner , R. Shirley , E. Lusso , H. Landt , G. Zamorani , M. Siudek
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B. Laloux T. Matamoro Zatarain F. Ricci S. Fotopoulou A. Ferr\'e-Mateu X. Lopez Lopez N. Aghanim B. Altieri A. Amara S. Andreon N. Auricchio H. Aussel C. Baccigalupi M. Baldi A. Balestra S. Bardelli P. Battaglia A. Biviano A. Bonchi E. Branchini M. Brescia J. Brinchmann S. Camera G. Ca\~nas-Herrera V. Capobianco C. Carbone J. Carretero S. Casas M. Castellano G. Castignani S. Cavuoti K. C. Chambers A. Cimatti C. Colodro-Conde G. Congedo C. J. Conselice L. Conversi Y. Copin F. Courbin H. M. Courtois M. Cropper A. Da Silva H. Degaudenzi G. De Lucia A. M. Di Giorgio C. Dolding H. Dole F. Dubath C. A. J. Duncan X. Dupac S. Dusini S. Escoffier M. Fabricius M. Farina R. Farinelli F. Faustini S. Ferriol F. Finelli P. Fosalba N. Fourmanoit M. Frailis E. Franceschi S. Galeotta K. George B. Gillis C. Giocoli J. Gracia-Carpio B. R. Granett A. Grazian F. Grupp S. Gwyn S. V. H. Haugan W. Holmes I. M. Hook F. Hormuth A. Hornstrup P. Hudelot K. Jahnke M. Jhabvala E. Keih\"anen S. Kermiche A. Kiessling B. Kubik M. K\"ummel M. Kunz H. Kurki-Suonio Q. Le Boulc'h A. M. C. Le Brun D. Le Mignant S. Ligori P. B. Lilje V. Lindholm I. Lloro G. Mainetti D. Maino E. Maiorano O. Mansutti S. Marcin O. Marggraf M. Martinelli N. Martinet F. Marulli R. Massey D. C. Masters E. Medinaceli S. Mei M. Melchior Y. Mellier M. Meneghetti E. Merlin G. Meylan A. Mora M. Moresco L. Moscardini R. Nakajima C. Neissner S.-M. Niemi J. W. Nightingale C. Padilla S. Paltani F. Pasian K. Pedersen W. J. Percival V. Pettorino S. Pires G. Polenta M. Poncet L. A. Popa L. Pozzetti F. Raison R. Rebolo A. Renzi J. Rhodes G. Riccio E. Romelli M. Roncarelli R. Saglia Z. Sakr A. G. S\'anchez D. Sapone B. Sartoris J. A. Schewtschenko M. Schirmer P. Schneider T. Schrabback A. Secroun G. Seidel M. Seiffert S. Serrano P. Simon C. Sirignano G. Sirri L. Stanco J. Steinwagner P. Tallada-Cresp\'i D. Tavagnacco A. N. Taylor I. Tereno S. Toft R. Toledo-Moreo F. Torradeflot I. Tutusaus L. Valenziano J. Valiviita T. Vassallo G. Verdoes Kleijn A. Veropalumbo Y. Wang J. Weller A. Zacchei F. M. Zerbi I. A. Zinchenko E. Zucca V. Allevato M. Ballardini M. Bolzonella E. Bozzo C. Burigana R. Cabanac A. Cappi D. Di Ferdinando J. A. Escartin Vigo L. Gabarra M. Huertas-Company J. Mart\'in-Fleitas S. Matthew N. Mauri R. B. Metcalf A. Pezzotta M. P\"ontinen C. Porciani I. Risso V. Scottez M. Sereno M. Tenti M. Viel M. Wiesmann Y. Akrami I. T. Andika S. Anselmi M. Archidiacono F. Atrio-Barandela C. Benoist K. Benson D. Bertacca M. Bethermin L. Bisigello A. Blanchard L. Blot H. B\"ohringer M. L. Brown S. Bruton A. Calabro F. Caro C. S. Carvalho T. Castro F. Cogato A. R. Cooray O. Cucciati S. Davini F. De Paolis G. Desprez A. D\'iaz-S\'anchez J. J. Diaz S. Di Domizio J. M. Diego A. Enia Y. Fang A. G. Ferrari A. Finoguenov A. Fontana A. Franco K. Ganga J. Garc\'ia-Bellido T. Gasparetto V. Gautard E. Gaztanaga F. Giacomini F. Gianotti G. Gozaliasl M. Guidi C. M. Gutierrez A. Hall W. G. Hartley S. Hemmati C. Hern\'andez-Monteagudo H. Hildebrandt J. Hjorth J. J. E. Kajava Y. Kang V. Kansal D. Karagiannis K. Kiiveri C. C. Kirkpatrick S. Kruk J. Le Graet L. Legrand M. Lembo F. Lepori G. Leroy G. F. Lesci J. Lesgourgues L. Leuzzi T. I. Liaudat A. Loureiro J. Macias-Perez G. Maggio M. Magliocchetti F. Mannucci R. Maoli C. J. A. P. Martins L. Maurin M. Miluzio P. Monaco C. Moretti G. Morgante K. Naidoo A. Navarro-Alsina S. Nesseris F. Passalacqua K. Paterson L. Patrizii A. Pisani D. Potter S. Quai M. Radovich S. Sacquegna M. Sahl\'en D. B. Sanders E. Sarpa A. Schneider D. Sciotti E. Sellentin F. Shankar L. C. Smith K. Tanidis G. Testera R. Teyssier S. Tosi A. Troja M. Tucci C. Valieri A. Venhola D. Vergani G. Verza P. Vielzeuf A. Viitanen N. A. Walton E. Soubrie D. Scott
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keywords x-raysourcesctpsdataeuclidextragalacticreleasegalactic
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To better understand the role of active galactic nuclei (AGN) in galaxy evolution, it is crucial to achieve a complete and pure AGN census. X-ray surveys are key to this, but identifying their counterparts (CTPs) at other wavelengths remains challenging due to their larger positional uncertainties and limited availability of deeper, uniform ancillary data. Euclid is revolutionising this effort, offering extensive coverage of nearly the entire extragalactic sky, particularly in the near-infrared bands, where AGN are more easily detected. With the first Euclid Quick Data Release (Q1), we identifyed, classifyed, and determined the redshifts of Euclid CTPs to known point-like sources from major X-ray surveys, including XMM-Newton, Chandra, and eROSITA. Using Bayesian statistics, combined with machine learning (ML), we identify the CTPs to 11 286 X-ray sources from the three X-ray telescopes. For the large majority of 10 194 sources, the associations are unique, with the remaining $\sim$ 10% of multi-CTP cases equally split between XMM-Newton and eROSITA. ML is then used to distinguish between Galactic (8%) and extragalactic (92%) sources. We computed photo-zs using deep learning for the 8617 sources detected in the 10th data release of the DESI Legacy Survey, reaching an accuracy and a fraction of outliers of about 5%. Based on their X-ray luminosities, over 99% of CTPs identified as extragalactic are classified as AGN, most of which appear unobscured given their hardness ratios. With this paper, we release our catalogue, which includes identifiers, basic X-ray properties, the details of the associations, and additional features such as Galactic/extragalactic classifications and photometric/spectroscopic redshifts. We also provide probabilities for sub-selecting the sample based on purity and completeness, allowing users to tailor the sample according to their specific needs.

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