Article

Euclid Quick Data Release (Q1)

B. LalouxMax Planck Institute for Extraterrestrial PhysicsA. BongiornoNational Institute for AstrophysicsM. SalvatoMax Planck Institute for Extraterrestrial PhysicsV. AllevatoINAF-Osservatorio Astronomico di CapodimonteM. MezcuaInstitut d’Estudis Espacials de Catalunya (IEEC), Edifici RDIT, Campus UPCW. RosterMax Planck Institute for Extraterrestrial PhysicsT. Matamoro ZatarainSchool of Physics, HH Wills Physics Laboratory, University of Bristol, Tyndall AvenueS. PaltaniDepartment of Astronomy, University of GenevaR. ShirleyMax Planck Institute for Extraterrestrial PhysicsF. TarsitanoDepartment of Astronomy, University of GenevaC. SaulderUniversitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität MünchenS. FotopoulouSchool of Physics, HH Wills Physics Laboratory, University of Bristol, Tyndall AvenueC. AndonieMax Planck Institute for Extraterrestrial PhysicsJ. BuchnerMax Planck Institute for Extraterrestrial PhysicsF. La FrancaDepartment of Mathematics and Physics, Roma Tre UniversityV. Le BrunAix-Marseille Université, CNRS, CNES, LAMF. RicciDepartment of Mathematics and Physics, Roma Tre UniversityD. ScottDepartment of Physics and Astronomy, University of British ColumbiaF. ShankarSchool of Physics & Astronomy, University of Southampton, Highfield CampusM. SiudekUniversidad de La Laguna, Dpto. AstrofísicaJ. G. SorceUniversité Paris-Saclay, CNRS, Institut d’astrophysique spatialeL. SpinoglioINAF-Istituto di Astrofisica e Planetologia SpazialiY. TobaAcademia Sinica Institute of Astronomy and Astrophysics (ASIAA)A. ViitanenNational Institute for AstrophysicsL. WangSRON Netherlands Institute for Space Research, Landleven 12G. ZamoraniINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaS. AndreonINAF-Osservatorio Astronomico di BreraN AuricchioINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaC BaccigalupiSISSA, International School for Advanced StudiesM. BaldiINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaA. BalestraINAF-Osservatorio Astronomico di PadovaS. BardelliINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaP. BattagliaINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaA. BivianoIFPU, Institute for Fundamental Physics of the UniverseE. BranchiniINFN-Sezione di GenovaM. BresciaINAF-Osservatorio Astronomico di CapodimonteS. CameraINFN-Sezione di TorinoG. Cañas-HerreraLeiden Observatory, Leiden UniversityV. CapobiancoINAF-Osservatorio Astrofisico di TorinoC. CarboneINAF-IASF MilanoJ. CarreteroPort d’Informació Científica, Campus UAB, C. Albareda s/nS. CasasDeutsches Zentrum für Luft- und Raumfahrt e. V. (DLR), Linder HöheM. CastellanoINAF-Osservatorio Astronomico di RomaG CastignaniINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaS. CavuotiINAF-Osservatorio Astronomico di CapodimonteK. C. ChambersInstitute for Astronomy, University of HawaiiA CimattiDipartimento di Fisica e Astronomia “Augusto Righi” – Alma Mater Studiorum Università di BolognaC. Colodro-CondeInstituto de Astrofísica de CanariasG. CongedoInstitute for Astronomy, University of Edinburgh, Royal Observatory, Blackford HillC. J. ConseliceJodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of ManchesterL. ConversiEuropean Space Agency/ESRIN, Largo Galileo Galilei 1Y. CopinUniversité Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822A. CostilleAix-Marseille Université, CNRS, CNES, LAMF. CourbinInstitució Catalana de Recerca i Estudis Avançats (ICREA), Passeig de Lluís Companys 23H. M. CourtoisLyon CollegeM. CropperMullard Space Science Laboratory, University College London, Holmbury St MarA. Da SilvaDepartamento de Física, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, Campo GrandeH. DegaudenziDepartment of Astronomy, University of GenevaG De LuciaINAF-Osservatorio Astronomico di TriesteH. DoleUniversité Paris-Saclay, CNRS, Institut d’astrophysique spatialeF. DubathDepartment of Astronomy, University of GenevaC. A. J. DuncanUK Astronomy Technology CentreX. DupacESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del CastilloS. EscoffierAix-Marseille Université, CNRS/IN2P3, CPPMM. FabriciusMax Planck Institute for Extraterrestrial PhysicsM. FarinaINAF-Istituto di Astrofisica e Planetologia SpazialiR. FarinelliINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaS. FerriolCentre National de la Recherche ScientifiqueF. FinelliINFN-BolognaP. FosalbaInstitut d’Estudis Espacials de Catalunya (IEEC), Edifici RDIT, Campus UPCN. FourmanoitCentre de physique des particules de MarseilleM. FrailisINAF-Osservatorio Astronomico di TriesteE. FranceschiINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaM. FumanaINAF-IASF MilanoS. GaleottaINAF-Osservatorio Astronomico di TriesteK GeorgeUniversity Observatory, LMU Faculty of PhysicsB. GillisUK Astronomy Technology CentreC. GiocoliINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaJ Gracia-CarpioMax Planck Institute for Extraterrestrial PhysicsA. GrazianINAF-Osservatorio Astronomico di PadovaF. GruppUniversitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität MünchenS. GwynHerzberg Astronomy and Astrophysics Research CentreS. V. H. HauganInstitute of Theoretical Astrophysics, University of OsloH. HoekstraLeiden Observatory, Leiden UniversityW. HolmesJet Propulsion Laboratory, California Institute of TechnologyF. HormuthFelix Hormuth EngineeringA HornstrupTechnical University of DenmarkK. JahnkeMax-Planck-Institut für AstronomieM. JhabvalaNASA Goddard Space Flight CenterB. JoachimiS. KermicheAix-Marseille Université, CNRS/IN2P3, CPPMA. KiesslingJet Propulsion Laboratory, California Institute of TechnologyB. KubikCentre National de la Recherche ScientifiqueM. KümmelUniversitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität MünchenM. KunzLaboratoire de Physique ThéoriqueH Kurki-SuonioDepartment of PhysicsA. M. C. Le BrunLaboratoire d’etude de l’Univers et des phenomenes eXtremes, Observatoire de Paris, Université PSL, Sorbonne Université, CNRSS. LigoriINAF-Osservatorio Astrofisico di TorinoP. B. LiljeInstitute of Theoretical Astrophysics, University of OsloV. LindholmDepartment of Physics

2026

ABI

Abstract

The Euclid Quick Data Release (Q1) is a powerful dataset to study active galactic nuclei (AGN) and their host galaxies. Deriving their physical properties through multi-component spectral energy distribution (SED) fitting is a challenging task for AGN, but it is greatly aided by the Euclid near-infrared photometry. Here we present a new method of quantifying the reliability of SED-derived parameters, such as AGN bolometric and monochromatic luminosities, host’s stellar mass ( M ★ ), star-formation rate (SFR), and specific star-formation rate (sSFR), by using mock SEDs of AGN built by combining observed SEDs of QSOs and galaxies. We applied this methodology to the ∼1 million Q1 AGN candidates, constructing a catalogue of AGN and host galaxy properties, alongside their respective reliability values. With a reliability threshold at 0.5, we find 88% of sources to have robust stellar masses and 76% to have reliable AGN luminosities. Moreover, through SED fitting we also measured the AGN fraction ( f AGN ) of the total mid-infrared flux and we used its lower-limit to select AGN. A f AGN, low > 0.075 threshold yields 85% completeness and purity. Comparable to colour-colour AGN selections, this method has the advantage of being less affected by redshift evolution and exploring fainter magnitudes. Additionally, by comparing the AGN and host galaxy parameters across different identification methods, we find that the probed range in stellar mass and AGN luminosity can be quite different. This highlights the importance of combining different approaches and accounting for their selection biases when studying AGN and their role in galaxy evolution. Finally, for the X-ray detected sample, we present the X-ray to mid-IR luminosity relation, and the correlation between stellar mass and bolometric luminosity as a function of redshift, in good agreement with previous results.

Identifiers

DOI: 10.1051/0004-6361/202659340

Citations and references

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