A CEERS Discovery of an Accreting Supermassive Black Hole 570 Myr after the Big Bang: Identifying a Progenitor of Massive z > 6 Quasars
Papovich, Casey; Cole, Justin W.; Yang, Guang; Finkelstein, Steven L.; Burgarella, Denis; Pérez-González, Pablo G.; Seillé, Lise-Marie; Arrabal Haro, Pablo; Casey, Caitlin M.; Chworowsky, Katherine; Cleri, Nikko J.; Dickinson, Mark; Fontana, Adriano; Grazian, Andrea; Grogin, Norman A.; Hathi, Nimish P.; Holwerda, Benne W.; Hutchison, Taylor A.; Kartaltepe, Jeyhan S.; Kocevski, Dale D.; Koekemoer, Anton M.; Larson, Rebecca L.; Lucas, Ray A.; Pirzkal, Nor; Trump, Jonathan R.; Weiner, Benjamin J.; Wilkins, Stephen M.; Yung, L. Y. Aaron; Zavala, Jorge A.; Fujimoto, Seiji; Leung, Gene C. K.; Jung, Intae; Juneau, Stéphanie; Tacchella, Sandro; Rigby, Jane R.; Zitrin, Adi; Hirschmann, Michaela; Morales, Alexa M.; McGrath, Elizabeth J.; Bromm, Volker; Amorín, Ricardo O.; Gawiser, Eric; Champagne, Jaclyn B.; Zhang, Haowen; Behroozi, Peter; Chávez Ortiz, Óscar A.; Simons, Raymond C.; Harish, Santosh; Cox, Isabella G.; Bagley, Micaela; de La Vega, Alexander; Ceers Team
United States, United Kingdom, Japan, Netherlands, Israel, Chile, France, Denmark, Italy, Switzerland, Spain, Malta
Abstract
We report the discovery of an accreting supermassive black hole at z = 8.679. This galaxy, denoted here as CEERS_1019, was previously discovered as a Lyα-break galaxy by Hubble with a Lyα redshift from Keck. As part of the Cosmic Evolution Early Release Science (CEERS) survey, we have observed this source with JWST/NIRSpec, MIRI, NIRCam, and NIRCam/WFSS and uncovered a plethora of emission lines. The Hβ line is best fit by a narrow plus a broad component, where the latter is measured at 2.5σ with an FWHM ~1200 km s-1. We conclude this originates in the broadline region of an active galactic nucleus (AGN). This is supported by the presence of weak high-ionization lines (N V, N IV], and C III]), as well as a spatial point-source component. The implied mass of the black hole (BH) is log (M BH/M ⊙) = 6.95 ± 0.37, and we estimate that it is accreting at 1.2 ± 0.5 times the Eddington limit. The 1-8 μm photometric spectral energy distribution shows a continuum dominated by starlight and constrains the host galaxy to be massive (log M/M⊙ ~9.5) and highly star-forming (star formation rate, or SFR ~ 30 M⊙ yr-1; log sSFR ~ - 7.9 yr-1). The line ratios show that the gas is metal-poor (Z/Z ⊙ ~ 0.1), dense (n e ~ 103 cm-3), and highly ionized (log U ~ - 2.1). We use this present highest-redshift AGN discovery to place constraints on BH seeding models and find that a combination of either super-Eddington accretion from stellar seeds or Eddington accretion from very massive BH seeds is required to form this object.