Article

Euclid preparation

Cao YeDepartment of Physics & Astronomy, University of California IrvineAsantha CoorayDepartment of Physics & Astronomy, University of California IrvineT. LiDepartment of Physics & Astronomy, University of California IrvineY. -T. ChengCalifornia Institute of TechnologyK. TanidisCenter for Astrophysics and Cosmology, University of Nova GoricaS. H. LimCavendish Laboratory, University of CambridgeD. ScottDepartment of Physics and Astronomy, University of British ColumbiaB. AltieriESAC/ESAA AmaraSchool of Mathematics and Physics, University of SurreyS. AndreonINAF-Osservatorio Astronomico di BreraN. AuricchioINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaC. BaccigalupiSISSA, International School for Advanced StudiesMarco BaldiDipartimento di Fisica e Astronomia, Università di BolognaS. BardelliINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaA. BivianoIFPU, Institute for Fundamental Physics of the UniverseE. BranchiniDipartimento di Fisica, Università di GenovaM. BresciaDepartment of Physics “E. Pancini”, University Federico IIS. CameraINAF-Osservatorio Astrofisico di TorinoG Cañas-HerreraLeiden Observatory, Leiden UniversityV. CapobiancoINAF-Osservatorio Astrofisico di TorinoC. CarboneINAF-IASF MilanoJ. CarreteroPort d’Informació Científica, Campus UABSantiago CasasDeutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)M. 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 ObservatoryChristopher J. ConseliceJodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of ManchesterL. ConversiEuropean Space Research InstituteY. CopinUniversité Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822F. CourbinInstitut de Ciencies de l’Espai (IEEC-CSIC), Campus UABH. M. CourtoisUCB Lyon 1, CNRS/IN2P3, IUF, IP2I LyonJ.-C. CuillandreUniversité Paris-Saclay, Université Paris Cité, CEA, CNRS, AIMH. DegaudenziDepartment of Astronomy, University of GenevaG. De LuciaINAF-Osservatorio Astronomico di TriesteH. DoleUniversité Paris-SaclayM. DouspisUniversité Paris-Saclay, CNRS, Institut d’astrophysique spatialeF. DubathDepartment of Astronomy, University of GenevaX DupacESAC/ESAM. FarinaINAF-Istituto di Astrofisica e Planetologia SpazialiR FarinelliINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaF. FaustiniINAF-Osservatorio Astronomico di RomaS FerriolCentre National de la Recherche ScientifiqueF. Finelli⋆INAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaM. FrailisINAF-Osservatorio Astronomico di TriesteE. FranceschiINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaM. FumanaINAF-IASF MilanoS. GaleottaINAF-Osservatorio Astronomico di TriesteKoshy GeorgeB. GillisInstitute for Astronomy, University of Edinburgh, Royal ObservatoryC. 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. V. H. HauganInstitute of Theoretical Astrophysics, University of OsloW. HolmesJet Propulsion Laboratory, California Institute of TechnologyF. HormuthFelix Hormuth EngineeringA. HornstrupCosmic Dawn Center (DAWN)K. JahnkęMax-Planck-Institut für AstronomieM. JhabvalaNASA Goddard Space Flight CenterB. JoachimiDepartment of Physics and Astronomy, University College LondonS. KermicheAix-Marseille Université, CNRS/IN2P3, CPPMA. KiesslingJet Propulsion Laboratory, California Institute of TechnologyB. KubikCentre National de la Recherche ScientifiqueM. KunzUniversité de Genève, Département de Physique Théorique and Centre for Astroparticle PhysicsH. Kurki‐SuonioDepartment of Physics, P.O. Box 64, University of HelsinkiA. M. C. Le BrunUniversité Paris Sciences et LettresS. LigoriINAF-Osservatorio Astrofisico di TorinoP. B. LiljeInstitute of Theoretical Astrophysics, University of OsloV. LindholmDepartment of Physics, P.O. Box 64, University of HelsinkiI. LloroSKAO, Jodrell Bank, Lower WithingtonG. MainettiCentre de Calcul de l’IN2P3/CNRSD. MainoDipartimento di Fisica “Aldo Pontremoli”, Università degli Studi di MilanoE. MaioranoINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaO. MansuttiINAF-Osservatorio Astronomico di TriesteS. MarcinUniversity of Applied Sciences and Arts of Northwestern Switzerland, School of Computer ScienceO. MarggrafUniversität Bonn, Argelander-Institut für AstronomieM. MartinelliINAF-Osservatorio Astronomico di RomaN. MartinetAix-Marseille Université, CNRS, CNES, LAMF. MarulliINFN-Sezione di BolognaR. MasseyE. MedinaceliINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaS. MeiCNRS-UCB International Research Laboratory, Centre Pierre Binétruy, IRL2007, CPB-IN2P3Y MellierInstitut d’Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne UniversitéM. MeneghettiINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaE. MerlinINAF-Osservatorio Astronomico di RomaG. MeylanInstitute of Physics, Laboratory of Astrophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL)A. MoraTelespazio UK S.L. for European Space Agency (ESA)M. MorescoINAF-Osservatorio di Astrofisica e Scienza dello Spazio di BolognaL. MoscardiniDipartimento di Fisica e Astronomia “Augusto Righi” – Alma Mater Studiorum Università di BolognaC. NeissnerPort d’Informació Científica, Campus UABS.-M. NiemiEuropean Space Research and Technology CentreC PadillaInstitut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UABS. PaltaniDepartment of Astronomy, University of GenevaF. PasianINAF-Osservatorio Astronomico di TriesteK. PedersenDARK, Niels Bohr Institute, University of CopenhagenWill J. PercivalPerimeter Institute for Theoretical Physics, Waterloo

2026en

ABI

Abstract

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 100deg 2 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 1 σ and reduces 1 σ 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 10 11 –10 14 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.

Identifiers

DOI: 10.1051/0004-6361/202659192

Citations and references

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