<i>Euclid</i>: the potential of slitless infrared spectroscopy: a <i>z</i> = 5.4 quasar and new ultracool dwarfs
journal contribution
posted on 2025-09-19, 11:18 authored by E Bañados, V Le Brun, S Belladitta, I Momcheva, D Stern, J Wolf, M Ezziati, DJ Mortlock, A Humphrey, RL Smart, Sarah CasewellSarah Casewell, A Pérez-Garrido, B Goldman, EL Martín, A Mohandasan, C Reylé, C Dominguez-Tagle, Y Copin, E Lusso, Y Matsuoka, K McCarthy, F Ricci, H-W Rix, HJA Rottgering, J-T Schindler, JR Weaver, A Allaoui, T Bedrine, M Castellano, P-Y Chabaud, G Daste, F Dufresne, J Gracia-Carpio, M Kümmel, M Moresco, M Scodeggio, C Surace, D Vibert, A Balestra, A Bonnefoi, A Caillat, F Cogato, A Costille, S Dusini, S Ferriol, E Franceschi, W Gillard, K Jahnke, D Le Mignant, S Ligori, E Medinaceli, G Morgante, F Passalacqua, K Paterson, S Pires, C Sirignano, IT Andika, H Atek, D Barrado, S Bisogni, CJ Conselice, H Dannerbauer, R Decarli, H Dole, T Dupuy, A Feltre, S Fotopoulou, B Gillis, X Lopez Lopez, M Onoue, G Rodighiero, N Sedighi, F Shankar, M Siudek, L Spinoglio, D Vergani, G Vietri, F Walter, G Zamorani, MR Zapatero Osorio, J-Y Zhang, M Bethermin, N Aghanim, B Altieri, A Amara, S Andreon, C Baccigalupi, M Baldi, S Bardelli, A Basset, P Battaglia, A Biviano, A Bonchi, D Bonino, E Branchini, M Brescia, J Brinchmann, S Camera, V Capobianco, C Carbone, J Carretero, S Casas, G Castignani, S Cavuoti, A Cimatti, C Colodro-Conde, G Congedo, L Conversi, F Courbin, HM Courtois, M Cropper, J-G Cuby, A Da Silva, H Degaudenzi, G De Lucia, AM Di Giorgio, C Dolding, F Dubath, CAJ Duncan, X Dupac, A Ealet, M Farina, F Faustini, N Fourmanoit, M Frailis, S Galeotta, K George, C Giocoli, BR Granett, A Grazian, F Grupp, L Guzzo, SVH Haugan, J Hoar, H Hoekstra, W Holmes, I Hook, F Hormuth, A Hornstrup, P Hudelot, M Jhabvala, B Joachimi, E Keihänen, S Kermiche, B Kubik, K Kuijken, M Kunz, H Kurki-Suonio, PB Lilje, V Lindholm, I Lloro, G Mainetti, D Maino, E Maiorano, O Mansutti, O Marggraf, K Markovic, M Martinelli, N Martinet, F Marulli, R Massey, S Mei, Y Mellier, M Meneghetti, E Merlin, G Meylan, A Mora, L Moscardini, C Neissner, S-M Niemi, JW Nightingale, C Padilla, S Paltani, F Pasian, K Pedersen, WJ Percival, V Pettorino, G Polenta, M Poncet, LA Popa, L Pozzetti, F Raison, R Rebolo, A Renzi, J Rhodes, G Riccio, E Romelli, M Roncarelli, E Rossetti, R Saglia, Z Sakr, D Sapone, B Sartoris, JA Schewtschenko, M Schirmer, P Schneider, T Schrabback, A Secroun, E Sefusatti, G Seidel, M Seiffert, S Serrano, G Sirri, L Stanco, J Steinwagner, P Tallada-Crespí, AN Taylor, HI Teplitz, I Tereno, S Toft, R Toledo-Moreo, F Torradeflot, I Tutusaus, L Valenziano, J Valiviita, T Vassallo, G Verdoes Kleijn, A Veropalumbo, Y Wang, J Weller, FM Zerbi, E Zucca, M Bolzonella, C Burigana, R Cabanac, L Gabarra, V Scottez, M Viel, D Scott<p dir="ltr">We demonstrate the potential of Euclid ’s slitless spectroscopy to discover high-redshift ($z>5$) 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 ${\rm RG}_{\scriptscriptstyle \rm E}$) spectra of the newly discovered $z=5.404$ quasar EUCL J181530.01$+$652054.0, 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 ${\rm C \small {III]}}$ and ${\rm Mg {\small II}}$ emission lines in the NISP ${\rm RG}_{\scriptscriptstyle \rm E}$ 1206–1892 nm spectrum, and confirmed through optical spectroscopy from the Large Binocular Telescope. The NISP Blue Grism (NISP ${\rm BG}_{\scriptscriptstyle \rm E}$) 926–1366 nm spectrum confirms ${C {\small IV}}$ and $\rm{C \small {III]}}$ emission. NISP ${\rm RG}_{\scriptscriptstyle \rm E}$ can find bright quasars at $z\approx 5.5$ and $z\gtrsim 7$, redshift ranges that are challenging for photometric selection due to contamination from ultracool dwarfs. EUCL J181530.01$+$652054.0 is a high-excitation, broad absorption line quasar detected at 144 MHz by the LOw-Frequency Array ($L_{\rm 144}=4.0 \times 10^{25}\,$W Hz$^{-1}$). The quasar has a bolometric luminosity of $3\times 10^{12}\, {{\rm L}_{\odot }}{}$ and is powered by a $3.4\times 10^9\, {{\rm M}_{\odot }}$ black hole. The discovery of this bright quasar is noteworthy as fewer than one such object was expected in the $\approx$20 deg$^2$ 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 $14\, 000\,$deg$^2$ of the sky.</p>
History
Author affiliation
College of Science & Engineering Physics & AstronomyVersion
- VoR (Version of Record)
