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Lookup NU author(s): Dr James Nightingale
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2025 The Author(s). We demonstrate the potential of Euclid 's slitless spectroscopy to discover high-redshift (5$]]>) quasars and their main photometric contaminant, ultracool dwarfs. Sensitive infrared spectroscopy from space is able to efficiently identify both populations, as demonstrated by Euclid Near-Infrared Spectrometer and Photometer Red Grism (NISP) spectra of the newly discovered quasar EUCL J181530.01652054.0, as well as several ultracool dwarfs in the Euclid Deep Field North and the Euclid Early Release Observation field Abell 2764. The ultracool dwarfs were identified by cross-correlating their spectra with templates. The quasar was identified by its strong and broad and emission lines in the NISP 1206-1892 nm spectrum, and confirmed through optical spectroscopy from the Large Binocular Telescope. The NISP Blue Grism (NISP) 926-1366 nm spectrum confirms and emission. NISP can find bright quasars at and, redshift ranges that are challenging for photometric selection due to contamination from ultracool dwarfs. EUCL J181530.01652054.0 is a high-excitation, broad absorption line quasar detected at 144 MHz by the LOw-Frequency Array (W Hz). The quasar has a bolometric luminosity of and is powered by a black hole. The discovery of this bright quasar is noteworthy as fewer than one such object was expected in the 20 deg surveyed. This finding highlights the potential and effectiveness of NISP spectroscopy in identifying rare, luminous high-redshift quasars, previewing the census of these sources that Euclid's slitless spectroscopy will deliver over about deg of the sky.
Author(s): Banados E, Le Brun V, Belladitta S, Momcheva I, Stern D, Wolf J, Ezziati M, Mortlock DJ, Humphrey A, Smart RL, Casewell SL, Perez-Garrido A, Goldman B, Martin EL, Mohandasan A, Reyle C, Dominguez-Tagle C, Copin Y, Lusso E, Matsuoka Y, Mccarthy K, Ricci F, Rix H-W, Rottgering HJA, Schindler J-T, Weaver JR, Allaoui A, Bedrine T, Castellano M, Chabaud P-Y, Daste G, Dufresne F, Gracia-Carpio J, Kummel M, Moresco M, Scodeggio M, Surace C, Vibert D, Balestra A, Bonnefoi A, Caillat A, Cogato F, Costille A, Dusini S, Ferriol S, Franceschi E, Gillard W, Jahnke K, Le Mignant D, Ligori S, Medinaceli E, Morgante G, Passalacqua F, Paterson K, Pires S, Sirignano C, Andika IT, Atek H, Barrado D, Bisogni S, Conselice CJ, Dannerbauer H, Decarli R, Dole H, Dupuy T, Feltre A, Fotopoulou S, Gillis B, Lopez Lopez XL, Onoue M, Rodighiero G, Sedighi N, Shankar F, Siudek M, Spinoglio L, Vergani D, Vietri G, Walter F, Zamorani G, Zapatero Osorio MR, Zhang J-Y, Bethermin M, Aghanim N, Altieri B, Amara A, Andreon S, Baccigalupi C, Baldi M, Bardelli S, Basset A, Battaglia P, Biviano A, Bonchi A, Bonino D, Branchini E, Brescia M, Brinchmann J, Camera S, Capobianco V, Carbone C, Carretero J, Casas S, Castignani G, Cavuoti S, Cimatti A, Colodro-Conde C, Congedo G, Conversi L, Courbin F, Courtois HM, Cropper M, Cuby J-G, Da Silva A, Degaudenzi H, De Lucia G, Di Giorgio AM, Dolding C, Dubath F, Duncan CAJ, Dupac X, Ealet A, Farina M, Faustini F, Fourmanoit N, Frailis M, Galeotta S, George K, Giocoli C, Granett BR, Grazian A, Grupp F, Guzzo L, Haugan SVH, Hoar J, Hoekstra H, Holmes W, Hook I, Hormuth F, Hornstrup A, Hudelot P, Jhabvala M, Joachimi B, Keihanen E, Kermiche S, Kubik B, Kuijken K, Kunz M, Kurki-Suonio H, Lilje PB, Lindholm V, Lloro I, Mainetti G, Maino D, Maiorano E, Mansutti O, Marggraf O, Markovic K, Martinelli M, Martinet N, Marulli F, Massey R, Mei S, Mellier Y, Meneghetti M, Merlin E, Meylan G, Mora A, Moscardini L, Neissner C, Niemi S-M, Nightingale JW, Padilla C, Paltani S, Pasian F, Pedersen K, Percival WJ, Pettorino V, Polenta G, Poncet M, Popa LA, Pozzetti L, Raison F, Rebolo R, Renzi A, Rhodes J, Riccio G, Romelli E, Roncarelli M, Rossetti E, Saglia R, Sakr Z, Sapone D, Sartoris B, Schewtschenko JA, Schirmer M, Schneider P, Schrabback T, Secroun A, Sefusatti E, Seidel G, Seiffert M, Serrano S, Sirri G, Stanco L, Steinwagner J, Tallada-Crespi P, Taylor AN, Teplitz HI, 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, Zerbi FM, Zucca E, Bolzonella M, Burigana C, Cabanac R, Gabarra L, Scottez V, Viel M, Scott D
Publication type: Article
Publication status: Published
Journal: Monthly Notices of the Royal Astronomical Society
Year: 2025
Volume: 542
Issue: 2
Pages: 1088-1102
Print publication date: 01/09/2025
Online publication date: 04/08/2025
Acceptance date: 30/07/2025
Date deposited: 04/09/2025
ISSN (print): 0035-8711
ISSN (electronic): 1365-2966
Publisher: Oxford University Press
URL: https://doi.org/10.1093/mnras/staf1274
DOI: 10.1093/mnras/staf1274
Data Access Statement: The data used in this study can be accessed from the observatories’ public archives or the websites of the surveys mentioned in the acknowledgments. The data sets generated and analysed during this study are available from the corresponding author upon reasonable request.
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