Euclid Quick Data Release (Q1). Active galactic nuclei identification using diffusion-based inpainting of Euclid VIS images
Abstract
Light emission from galaxies exhibit diverse brightness profiles, influenced by factors such as galaxy type, structural features and interactions with other galaxies. Elliptical galaxies feature more uniform light distributions, while spiral and irregular galaxies have complex, varied light profiles due to their structural heterogeneity and star-forming activity. In addition, galaxies with an active galactic nucleus (AGN) feature intense, concentrated emission from gas accretion around supermassive black holes, superimposed on regular galactic light, while quasi-stellar objects (QSO) are the extreme case of the AGN emission dominating the galaxy. The challenge of identifying AGN and QSO has been discussed many times in the literature, often requiring multi-wavelength observations. This paper introduces a novel approach to identify AGN and QSO from a single image. Diffusion models have been recently developed in the machine-learning literature to generate realistic-looking images of everyday objects. Utilising the spatial resolving power of the Euclid VIS images, we created a diffusion model trained on one million sources, without using any source pre-selection or labels. The model learns to reconstruct light distributions of normal galaxies, since the population is dominated by them. We condition the prediction of the central light distribution by masking the central few pixels of each source and reconstruct the light according to the diffusion model. We further use this prediction to identify sources that deviate from this profile by examining the reconstruction error of the few central pixels regenerated in each source's core. Our approach, solely using VIS imaging, features high completeness compared to traditional methods of AGN and QSO selection, including optical, near-infrared, mid-infrared, and X-rays.
Keywords
Cite
@article{arxiv.2503.15321,
title = {Euclid Quick Data Release (Q1). Active galactic nuclei identification using diffusion-based inpainting of Euclid VIS images},
author = {Euclid Collaboration and G. Stevens and S. Fotopoulou and M. N. Bremer and T. Matamoro Zatarain and K. Jahnke and B. Margalef-Bentabol and M. Huertas-Company and M. J. Smith and M. Walmsley and M. Salvato and M. Mezcua and A. Paulino-Afonso and M. Siudek and M. Talia and F. Ricci and W. Roster and N. Aghanim and B. Altieri and S. Andreon and H. Aussel and C. Baccigalupi and M. Baldi and S. Bardelli and P. Battaglia and A. Biviano and A. Bonchi and E. Branchini and M. Brescia and J. Brinchmann and S. Camera and G. Cañas-Herrera and V. Capobianco and C. Carbone and J. Carretero and M. Castellano and G. Castignani and S. Cavuoti and K. C. Chambers and A. Cimatti and C. Colodro-Conde and G. Congedo and C. J. Conselice and L. Conversi and Y. Copin and A. Costille and F. Courbin and H. M. Courtois and M. Cropper and A. Da Silva and H. Degaudenzi and G. De Lucia and C. Dolding and H. Dole and M. Douspis and F. Dubath and X. Dupac and S. Dusini and S. Escoffier and M. Farina and S. Ferriol and K. George and C. Giocoli and B. R. Granett and A. Grazian and F. Grupp and S. V. H. Haugan and I. M. Hook and F. Hormuth and A. Hornstrup and P. Hudelot and M. Jhabvala and E. Keihänen and S. Kermiche and A. Kiessling and M. Kilbinger and B. Kubik and M. Kümmel and H. Kurki-Suonio and Q. Le Boulc'h and A. M. C. Le Brun and D. Le Mignant and P. B. Lilje and V. Lindholm and I. Lloro and G. Mainetti and D. Maino and E. Maiorano and O. Marggraf and M. Martinelli and N. Martinet and F. Marulli and R. Massey and S. Maurogordato and H. J. McCracken and E. Medinaceli and S. Mei and M. Melchior and M. Meneghetti and E. Merlin and G. Meylan and A. Mora and M. Moresco and L. Moscardini and R. Nakajima and C. Neissner and S. -M. Niemi and C. Padilla and S. Paltani and F. Pasian and K. Pedersen and W. J. Percival and V. Pettorino and G. Polenta and M. Poncet and L. A. Popa and L. Pozzetti and F. Raison and R. Rebolo and A. Renzi and J. Rhodes and G. Riccio and E. Romelli and M. Roncarelli and R. Saglia and A. G. Sánchez and D. Sapone and J. A. Schewtschenko and M. Schirmer and P. Schneider and T. Schrabback and A. Secroun and S. Serrano and P. Simon and C. Sirignano and G. Sirri and J. Skottfelt and L. Stanco and J. Steinwagner and P. Tallada-Crespí and A. N. Taylor and I. Tereno and S. Toft and R. Toledo-Moreo and F. Torradeflot and I. Tutusaus and L. Valenziano and J. Valiviita and T. Vassallo and G. Verdoes Kleijn and A. Veropalumbo and Y. Wang and J. Weller and A. Zacchei and G. Zamorani and F. M. Zerbi and I. A. Zinchenko and E. Zucca and V. Allevato and M. Ballardini and M. Bolzonella and E. Bozzo and C. Burigana and R. Cabanac and A. Cappi and J. A. Escartin Vigo and L. Gabarra and W. G. Hartley and J. Martín-Fleitas and S. Matthew and R. B. Metcalf and A. Pezzotta and M. Pöntinen and I. Risso and V. Scottez and M. Sereno and M. Tenti and M. Wiesmann and Y. Akrami and S. Alvi and I. T. Andika and S. Anselmi and M. Archidiacono and F. Atrio-Barandela and D. Bertacca and M. Bethermin and L. Bisigello and A. Blanchard and L. Blot and S. Borgani and M. L. Brown and S. Bruton and A. Calabro and F. Caro and T. Castro and F. Cogato and S. Davini and G. Desprez and A. Díaz-Sánchez and J. J. Diaz and S. Di Domizio and J. M. Diego and P. -A. Duc and A. Enia and Y. Fang and A. G. Ferrari and A. Finoguenov and A. Fontana and A. Franco and J. García-Bellido and T. Gasparetto and V. Gautard and E. Gaztanaga and F. Giacomini and F. Gianotti and M. Guidi and C. M. Gutierrez and A. Hall and S. Hemmati and H. Hildebrandt and J. Hjorth and J. J. E. Kajava and Y. Kang and V. Kansal and D. Karagiannis and C. C. Kirkpatrick and S. Kruk and L. Legrand and M. Lembo and F. Lepori and G. Leroy and J. Lesgourgues and L. Leuzzi and T. I. Liaudat and J. Macias-Perez and M. Magliocchetti and F. Mannucci and R. Maoli and C. J. A. P. Martins and L. Maurin and M. Miluzio and P. Monaco and G. Morgante and K. Naidoo and A. Navarro-Alsina and F. Passalacqua and K. Paterson and L. Patrizii and A. Pisani and D. Potter and S. Quai and M. Radovich and P. -F. Rocci and G. Rodighiero and S. Sacquegna and M. Sahlén and D. B. Sanders and E. Sarpa and A. Schneider and M. Schultheis and D. Sciotti and E. Sellentin and F. Shankar and L. C. Smith and K. Tanidis and G. Testera and R. Teyssier and S. Tosi and A. Troja and M. Tucci and C. Valieri and D. Vergani and G. Verza and N. A. Walton},
journal= {arXiv preprint arXiv:2503.15321},
year = {2025}
}
Comments
Paper Accepted as part of the A&A Special Issue `Euclid Quick Data Release (Q1)', 34 pages, 26 figures