J/A+A/711/A20ivo://CDS.VizieR/J/A+A/711/A20CDSEuclid Collaboration: Matamoro Zatarain T.Fotopoulou S.Ricci F.,Bolzonella M.La Franca F.Viitanen A.Zamorani G.Taylor M.B.,Mezcua M.Laloux B.Bongiorno A.Jahnke K.Stevens G.Shaw R.A.,Bisigello L.Roster W.Fu Y.Margalef-Bentabol B.La Marca A.,Tarsitano F.Feltre A.Calhau J.Lopez Lopez X.Scialpi M.Salvato M.,Allevato V.Siudek M.Saulder C.Vergani D.Bremer M.N.Wang L.,Giulietti M.Alexander D.M.Sluse D.Shankar F.Spinoglio L.Scott D.,Shirley R.Landt H.Selwood M.Toba Y.Dayal P.Aghanim N.Altieri B.,Amara A.Andreon S.Auricchio N.Aussel H.Baccigalupi C.Baldi M.,Bardelli S.Basset A.Battaglia P.Biviano A.Bonchi A.Branchini E.,Brescia M.Brinchmann J.Camera S.Canas-Herrera G.Capobianco V.,Carbone C.Carretero J.Casas S.Castander F.J.Castellano M.,Castignani G.Cavuoti S.Chambers K.C.Cimatti A.Colodro-Conde C.,Congedo G.Conselice C.J.Conversi L.Copin Y.Courbin F.,Courtois H.M.Cropper M.Da Silva A.Degaudenzi H.De Lucia G.,Di Giorgio A.M.Dolding C.Dole H.Dubath F.Duncan C.A.J.Dupac X.,Dusini S.Ealet A.Escoffier S.Fabricius M.Farina M.Farinelli R.,Faustini F.Ferriol S.Finelli F.Fourmanoit N.Frailis M.,Franceschi E.Galeotta S.George K.Gillis B.Giocoli C.,Gomez-Alvarez P.Gracia-Carpio J.Granett B.R.Grazian A.Grupp F.,Gwyn S.Haugan S.V.H.Hoekstra H.Holmes W.Hook I.M.Hormuth F.,Hornstrup A.Hudelot P.Jhabvala M.Keihaenen E.Kermiche S.,Kiessling A.Kubik B.Kuemmel M.Kunz M.Kurki-Suonio H.Le Boulc'h Q.,Le Brun A.M.C.Le Mignant D.Liebing P.Ligori S.Lilje P.B.,Lindholm V.Lloro I.Mainetti G.Maino D.Maiorano E.Mansutti O.,Marcin S.Marggraf O.Martinelli M.Martinet N.Marulli F.Massey R.,Masters D.C.Maurogordato S.Medinaceli E.Mei S.Melchior M.,Mellier Y.Meneghetti M.Merlin E.Meylan G.Mora A.Moresco M.,Moscardini L.Nakajima R.Neissner C.Niemi S.-M.Nightingale J.W.,Padilla C.Paltani S.Pasian F.Pedersen K.Percival W.J.Pettorino V.,Pires S.Polenta G.Poncet M.Popa L.A.Pozzetti L.Raison F.,Rebolo R.Renzi A.Rhodes J.Riccio G.Romelli E.Roncarelli M.,Rossetti E.Rottgering H.J.A.Rusholme B.Saglia R.Sakr Z.,Sanchez A.G.Sapone D.Sartoris B.Schewtschenko J.A.Schneider P.,Schrabback T.Scodeggio M.Secroun A.Seidel G.Seiffert M.Serrano S.,Simon P.Sirignano C.Sirri G.Skottfelt J.Stanco L.Steinwagner J.,Tallada-Crespi P.Taylor A.N.Tereno I.Toft S.Toledo-Moreo R.,Torradeflot F.Tutusaus I.Valenziano L.Valiviita J.Vassallo T.,Verdoes Kleijn G.Veropalumbo A.Wang Y.Weller J.Zacchei A.,Zerbi F.M.Zinchenko I.A.Zucca E.Ballardini M.Bozzo E.Burigana C.,Cabanac R.Cappi A.Di Ferdinando D.Escartin Vigo J.A.Fabbian G.,Gabarra L.Martin-Fleitas J.Matthew S.Mauri N.Metcalf R.B.,Pezzotta A.Poentinen M.Porciani C.Risso I.Scottez V.Sereno M.,Tenti M.Viel M.Wiesmann M.Akrami Y.Andika I.T.Anselmi S.,Archidiacono M.Atrio-Barandela F.Benoist C.Benson K.Bertacca D.,Bethermin M.Blanchard A.Blot L.Boehringer H.Brown M.L.Bruton S.,Calabro A.Camacho Quevedo B.Caro F.Carvalho C.S.Castro T.,Cogato F.Contini T.Cooray A.R.Cucciati O.Davini S.De Paolis F.,Desprez G.Diaz-Sanchez A.Diaz J.J.Di Domizio S.Diego J.M.,Duc P.-A.Enia A.Fang Y.Ferrari A.G.Finoguenov A.Fontana A.,Fontanot F.Franco A.Ganga K.Garcia-Bellido J.Gasparetto T.,Gautard V.Gaztanaga E.Giacomini F.Gianotti F.Gozaliasl G.,Gregorio A.Guidi M.Gutierrez C.M.Hall A.Hartley W.G.Hemmati S.,Hernandez-Monteagudo C.Hildebrandt H.Hjorth J.Kajava J.J.E.Kang Y.,Kansal V.Karagiannis D.Kiiveri K.Kirkpatrick C.C.Kruk S.,Legrand L.Lembo M.Lepori F.Leroy G.Lesci G.F.Lesgourgues J.,Leuzzi L.Liaudat T.I.Loureiro A.Macias-Perez J.Maggio G.,Magliocchetti M.Magnier E.A.Mannucci F.Maoli R.Martins C.J.A.P.,Maurin L.Miluzio M.Monaco P.Moretti C.Morgante G.Murray C.,Naidoo K.Navarro-Alsina A.Nesseris S.Passalacqua F.Paterson K.,Patrizii L.Pisani A.Potter D.Quai S.Radovich M.Rocci P.-F.,Rodighiero G.Sacquegna S.Sahlen M.Sanders D.B.Sarpa E.,Schneider A.Schultheis M.Sciotti D.Sellentin E.Shulevski A.,Smith L.C.Stanford S.A.Tanidis K.Testera G.Teyssier R.Tosi S.,Troja A.Tucci M.Valieri C.Venhola A.Verza G.Vielzeuf P.,Walton N.A.Soubrie E.2026-06-30T15:40:05Z2026-06-30T16:27:37ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.fractive-galactic-nucleiquasarssurveysWe present three catalogues of candidate active galactic nuclei (AGN) in the Euclid Quick Release (Q1) fields. For each Euclid source we collect multi-wavelength photometric and spectroscopic information from surveys such as the Galaxy Evolution Explorer (GALEX), Gaia, Dark Energy Survey (DES), Wide-field Infrared Survey Explorer (WISE), Spitzer, Dark Energy Spectroscopic Instrument (DESI), and Sloan Digital Sky Survey (SDSS), including spectroscopic redshifts from public compilations when available. We investigate the AGN content of the Q1 fields using multiple selection methods. Applying Euclid colours and WISE-AllWISE cuts, we identify 292222 and 65131 candidates, respectively. We compile a high-purity QSO catalogue based on Gaia DR3 information, containing 1971 candidates. Using spectroscopic information from DESI, we perform broad-line and narrow-line AGN selections, yielding 4392 AGN candidates across the Q1 fields. We investigate and refine the Euclid Q1 probabilistic random forest QSO population, selecting a refined sample of 180666 candidates. Additionally, we perform SED fitting on sources with available z_spec_ and, utilizing the derived AGN fraction, identify 7766 AGN candidates. To improve selection purity, we define two new colour criteria (JH_IeY and IeH_gz), finding 313714 and 267513 candidates, respectively, across the Q1 fields. We find a total of 229779 AGN candidates equivalent to an AGN surface density of 3641 deg^{-2} for 18<Ie<=24.5, and a subsample of 30422 candidates corresponding to an AGN surface density of 482 deg^{-2} when limiting the depth to 18<Ie<=22. The AGN surface densities recove2026A&A...711A..20Ehttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/711/A20CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/388 : Euclid final merged catalog. Q1 data releaseJ/A+A/711/A10 : Euclid (Q1). Census of dwarf galaxies (Euclid Coll., 2026)J/A+A/711/A16 : X-ray point-like sources of Euclid (Q1) (Euclid Coll.+, 2026)J/A+A/711/A37 : Ultracool dwarfs in Euclid Deep Fields (Zerjal+, 2026)J/A+A/711/A38 : Euclid Q1. Photometric studies of known transientsJ/A+A/711/A39 : Euclid Q1. Secondary nuclei in ET galaxies (Fabricius+, 2026)J/A+A/711/A20 : Galaxies of Euclid (Q1) (Euclid Coll.+, 2026)J/A+A/711/A24 : Euclid Q1. Little red dots properties (Euclid Coll., 2026)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/711/A20https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/711/A20http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/711/A20https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/711/A20https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/711/A20http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/711/A20GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/711/A20/edfn (Catalogue of sources for the EDF-N)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/711/A20/edfn?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/711/A20/edfn?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/711/A20/edfn?GETtext/xml+votable180.050000true262.4649539282865.750119882970.005555555555555556Cone search capability for table J/A+A/711/A20/edfs (Catalogue of sources for the EDF-S)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/711/A20/edfs?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/711/A20/edfs?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/711/A20/edfs?GETtext/xml+votable180.050000true55.75542164941-49.749266449120.005555555555555556Cone search capability for table J/A+A/711/A20/edff (Catalogue of sources for the EDF-F)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/711/A20/edff?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/711/A20/edff?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/711/A20/edff?GETtext/xml+votable180.050000true50.86507110846-28.035092901470.0055555555555555564/2145 5/2557 2559 2901 2903 3839 4010-4011 8506-8507 8579 8585 8592 8982-8983 8989 9032 6/10207 10233 10235 11601 11603 11609 11611 15343 15351 15353-15355 16034-16035 16038-16039 16056 16058 33979 33981-33983 34307 34309-34311 34313-34315 34336-34337 34339 34352-34353 34372 34374 34376-34377 35923 35926-35927 35952-35953 35955 35964-35965 36098 36104 36106-36107https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/711/A20?format=asciidefaultJ/A+A/711/A20/edfnCatalogue of sources for the EDF-NrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDESIBrGalCand[0/1] AGN candidate based on DESI SPECTYPE==GALAXY and presence of broad emission lines (DESI_broadline_galaxy_candidate) (G1)meta.codeAGNfrac? AGN fraction derived from SED fitting (AGN_fraction)phys.luminosity;arith.ratiodoublenullableEuclidEuclid unique source identifier (object_id_euclid)meta.id;meta.mainRAJ2000Euclid right ascension (J2000.0) (ra_euclid)degpos.eq.ra;meta.mainindexedDEJ2000Euclid declination (J2000.0) (dec_euclid)degpos.eq.dec;meta.mainindexedGalex? GALEX source identifier (object_id_galex)meta.idnullableRA1deg? GALEX right ascension (J2000.0) (ra_galex)degpos.eq.ranullableDE1deg? GALEX declination (J2000.0) (dec_galex)degpos.eq.decnullableGaia? Gaia unique source identifier (object_id_gaia)meta.idnullableRA2deg? Gaia right ascension (ICRS) (ra_gaia)degpos.eq.ranullableDE2deg? Gaia declination (ICRS) (dec_gaia)degpos.eq.decnullableRA4deg? WISE-AllWISE right ascension (J2000.0) (ra_allwise)degpos.eq.ranullableDE4deg? WISE-AllWISE declination (J2000.0) (dec_allwise)degpos.eq.decnullableDESI? DESI unique target ID (object_id_desi)meta.idnullableRA5deg? DESI right ascension (ICRS) (ra_desi)degpos.eq.ranullableDE5deg? DESI declination (ICRS) (dec_desi)degpos.eq.decnullablezDESI? DESI redshift measured by Redrock (Z_desi)src.redshift;pos.heliocentricdoublenullableSDSSSDSS object identification number (object_id_sdss)meta.idcharRA6deg? SDSS right ascension (J2000.0) (ra_sdss)degpos.eq.ranullableDE6deg? SDSS declination (J2000.0) (dec_sdss)degpos.eq.decnullablezSDSS? SDSS best available redshift taken from Z_VI, Z_PIPE, Z_DR12Q, Z_DR7Q_SCH, Z_DR6Q_HW, and Z_10K (Z_sdss)src.redshift;pos.heliocentricdoublenullableGoodFlags[0/1] Cleaning implemented to keep only those sources with `good flags' (good_flags) (G1)meta.codeintBrightVmagbin[0/1] Bright Ie magnitude bin: 18<Ie<=21 (bright_vis_mag_bin) (G1)meta.codeintMediumVmagbin[0/1] Medium Ie magnitude bin: 21<Ie<=22 (medium_vis_mag_bin) (G1)meta.codeintFaintVmagbin[0/1] Faint Ie magnitude bin: 22<Ie<=24.5 (faint_vis_mag_bin) (G1)meta.codeintCandGaia[0/1] Stellar candidate based on Gaia's proper motion and parallax (star_candidate_gaia) (G1)meta.codeintCandPRF[0/1] Stellar candidate based on Probabilistic Random Forest (PRF) star probability > 0.7 (star_candidate_PRF) (G1)meta.codeintCandAll[0/1] Stellar candidate based on CandGaia and/or CandPRF (star_candidate_all) (G1)meta.codeintPRFQSOCand[0/1] QSO candidate based on PRF QSO probability>0.85 (PRF_qso_candidate) (G1)meta.codeintB24aQSOCand[0/1] QSO candidate based on B24A (B24a_qso_candidate) (G1)meta.codeintB24bGNCand[0/1] QSO candidate based on B24B (B24b_qso_candidate) (G1)meta.codeintC75AGNCand[0/1] AGN candidate based on C75 (C75_agn_candidate) (G1)meta.codeintR90AGNCand[0/1] AGN candidate based on R90 (R90_agn_candidate) (G1)meta.codeintGDR3QSOCand[0/1] QSO candidate based on GDR3-QSO (GDR3_qso_candidate) (G1)meta.codeintJHIeYQSOCand[0/1] QSO candidate based on JH_IeY (JH_IeY_qso_candidate) (G1)meta.codeintIeHgzQSOCand[0/1] QSO candidate based on IeH_gz (IeH_gz_qso_candidate) (G1)meta.codeintDESIQSOCand[0/1] QSO candidate based on DESI SPECTYPE==QSO (DESI_qso_candidate) (G1)meta.codeDESIBrLneQSOCand[0/1] QSO candidate based on DESI SPECTYPE==QSO and presence of broad emission lines (DESI_broadline_qso_candidate) (G1)meta.codeDESINiiBPTAGNCand[0/1] AGN candidate based on DESI SPECTYPE==GALAXY and Nii BPT diagnostic (DESI_niibpt_agn_candidate) (G1)meta.codeDESISiiBPTAGNCand[0/1] AGN candidate based on DESI SPECTYPE==GALAXY and Sii BPT diagnostic (DESI_siibpt_agn_candidate) (G1)meta.codeDESIoiBPTAGNCand[0/1] AGN candidate based on DESI SPECTYPE==GALAXY and Oi BPT diagnostic (DESI_oibpt_agn_candidate) (G1)meta.codeDESIWhanAGNCand[0/1] AGN candidate based on DESI SPECTYPE==GALAXY and WHAN diagnostic (DESI_whan_agn_candidate) (G1)meta.codeDESIBlueAGNCand[0/1] AGN candidate based on DESI SPECTYPE==GALAXY and BLUE diagnostic (DESI_blue_agn_candidate) (G1)meta.codeDESIKexAGNCand[0/1] AGN candidate based on DESI SPECTYPE==GALAXY and KEX diagnostic ( DESI_kex_agn_candidate) (G1)meta.codee_AGNfrac? AGN fraction error derived from SED fitting (AGN_fraction_err)stat.errordoublenullableAGNsedCand[0/1]? AGN candidate based on AGN fraction >0.25 (AGN_sed_candidate) (G1)meta.codeintnullableAllwise? WISE-AllWISE unique source identifier (object_id_allwise)meta.idcharJ/A+A/711/A20/edfsCatalogue of sources for the EDF-SrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEuclidEuclid unique source identifier (object_id_euclid)meta.id;meta.mainRAJ2000Euclid right ascension (J2000.0) (ra_euclid)degpos.eq.ra;meta.mainindexedDEJ2000Euclid declination (J2000.0) (dec_euclid)degpos.eq.dec;meta.mainindexedGalex? GALEX source identifier (object_id_galex)meta.idnullableRA1deg? GALEX right ascension (J2000.0) (ra_galex)degpos.eq.ranullableDE1deg? GALEX declination (J2000.0) (dec_galex)degpos.eq.decnullableGaia? Gaia unique source identifier (object_id_gaia)meta.idnullableRA2deg? Gaia right ascension (ICRS) (ra_gaia)degpos.eq.ranullableDE2deg? Gaia declination (ICRS) (dec_gaia)degpos.eq.decnullableDES? DES unique identifier for the coadded objects (object_id_des)meta.idnullableRA7deg? DES right ascension (J2000.0) (ra_des)degpos.eq.ranullableDE7deg? DES declination (J2000.0) (dec_des)degpos.eq.decnullableAllwiseWISE-AllWISE unique source identifier (object_id_allwise)meta.idcharRA4deg? WISE-AllWISE right ascension (J2000.0) (ra_allwise)degpos.eq.ranullableDE4deg? WISE-AllWISE declination (J2000.0) (dec_allwise)degpos.eq.decnullableGoodFlags[0/1] Cleaning implemented to keep only those sources with `good flags' (good_flags) (G1)meta.codeintBrightVmagbin[0/1] Bright Ie magnitude bin: 18<Ie<=21 (bright_vis_mag_bin) (G1)meta.codeintMediumVmagbin[0/1] Medium Ie magnitude bin: 21<Ie<=22 (medium_vis_mag_bin) (G1)meta.codeintFaintVmagbin[0/1] Faint Ie magnitude bin: 22<Ie<=24.5 (faint_vis_mag_bin) (G1)meta.codeintCandGaia[0/1] Stellar candidate based on Gaia's proper motion and parallax (star_candidate_gaia) (G1)meta.codeintCandPRF[0/1] Stellar candidate based on Probabilistic Random Forest (PRF) star probability >0.7 (star_candidate_PRF) (G1)meta.codeintCandAll[0/1] Stellar candidate based on CandGaia and/or CandPRF (star_candidate_all) (G1)meta.codeintPRFQSOCand[0/1] QSO candidate based on PRF QSO probability>0.95 (PRF_qso_candidate) (G1)meta.codeintB24aQSOCand[0/1] QSO candidate based on B24A (B24a_qso_candidate) (G1)meta.codeintC75AGNCand[0/1] AGN candidate based on C75 (C75_agn_candidate) (G1)meta.codeintR90AGNCand[0/1] AGN candidate based on R90 (R90_agn_candidate) (G1)meta.codeintGDR3QSOCand[0/1] QSO candidate based on GDR3-QSO (GDR3_qso_candidate) (G1)meta.codeintJHIeYQSOCand[0/1] QSO candidate based on JH_IeY (JH_IeY_qso_candidate) (G1)meta.codeintIeHgzQSOCand[0/1] QSO candidate based on IeH_gz (IeH_gz_qso_candidate) (G1)meta.codeintJ/A+A/711/A20/edffCatalogue of sources for the EDF-FDE3deg? DES declination (J2000.0) (dec_des)degpos.eq.decnullableAllwise? WISE-AllWISE unique source identifier (object_id_allwise)meta.idcharRA4deg? WISE-AllWISE right ascension (J2000.0) (ra_allwise)degpos.eq.ranullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEuclidEuclid unique source identifier (object_id_euclid)meta.id;meta.mainRAJ2000Euclid right ascension (J2000.0) (ra_euclid)degpos.eq.ra;meta.mainindexedDEJ2000Euclid declination (J2000.0) (dec_euclid)degpos.eq.dec;meta.mainindexedGalex? GALEX source identifier (object_id_galex)meta.idnullableRA1deg? GALEX right ascension (J2000.0) (ra_galex)degpos.eq.ranullableDE1deg? GALEX declination (J2000.0) (dec_galex)degpos.eq.decnullableGaia? Gaia unique source identifier (object_id_gaia)meta.idnullableRA2deg? Gaia right ascension (ICRS) at Ep=2016.0 (ra_gaia)degpos.eq.ranullableDE2deg? Gaia declination (ICRS) at Ep=2016.0 (dec_gaia)degpos.eq.decnullableDES? DES unique identifier for the coadded objects (object_id_des)meta.idnullableRA3deg? DES right ascension (J2000.0) (ra_des)degpos.eq.ranullableDE4deg? WISE-AllWISE declination (J2000.0) (dec_allwise)degpos.eq.decnullableGoodFlags[0/1] Cleaning implemented to keep only those sources with `good flags' (good_flags) (G1)meta.codeintBrightVmagbin[0/1] Bright Ie magnitude bin: 18<Ie<=21 (bright_vis_mag_bin) (G1)meta.codeintMediumVmagbin[0/1] Medium Ie magnitude bin: 21<Ie<=22 (medium_vis_mag_bin) (G1)meta.codeintFaintVmagbin[0/1] Faint Ie magnitude bin: 22<Ie<=24.5 (faint_vis_mag_bin) (G1)meta.codeintCandGaia[0/1] Stellar candidate based on Gaia's proper motion and parallax (star_candidate_gaia) (G1)meta.codeintCandPRF[0/1] Stellar candidate based on Probabilistic Random Forest (PRF) star probability > 0.7 (star_candidate_PRF) (G1)meta.codeintCandAll[0/1] Stellar candidate based on CandGaia and/or CandPRF (star_candidate_all) (G1)meta.codeintPRFQSOCand[0/1] QSO candidate based on PRF QSO probability>0.95 (PRF_qso_candidate) (G1)meta.codeintB24aQSOCand[0/1] QSO candidate based on B24A (B24a_qso_candidate) (G1)meta.codeintC75AGNCand[0/1] AGN candidate based on C75 (C75_agn_candidate) (G1)meta.codeintR90AGNCand[0/1] AGN candidate based on R90 (R90_agn_candidate) (G1)meta.codeintGDR3QSOCand[0/1] QSO candidate based on GDR3-QSO (GDR3_qso_candidate) (G1)meta.codeintJHIeYQSOCand[0/1] QSO candidate based on JH_IeY (JH_IeY_qso_candidate) (G1)meta.codeintIeHgzQSOCand[0/1] QSO candidate based on IeH_gz (IeH_gz_qso_candidate) (G1)meta.codeint