Paper
UNCOVER spectroscopy confirms a surprising ubiquity of AGN in red galaxies at $z>5$
Authors
Jenny E. Greene, Ivo Labbe, Andy D. Goulding, Lukas J. Furtak, Iryna Chemerynska, Vasily Kokorev, Pratika Dayal, Christina C. Williams, Bingjie Wang, David J. Setton, Adam J. Burgasser, Rachel Bezanson, Hakim Atek, Gabriel Brammer, Sam E. Cutler, Robert Feldmann, Seiji Fujimoto, Karl Glazebrook, Anna de Graaff, Joel Leja, Danilo Marchesini, Michael V. Maseda, Jorryt Matthee, Tim B. Miller, Rohan P. Naidu, Themiya Nanayakkara, Pascal A. Oesch, Richard Pan, Casey Papovich, Sedona H. Price, Pieter van Dokkum, John R. Weaver, Katherine E. Whitaker, Adi Zitrin
Abstract
JWST is revealing a new population of dust-reddened broad-line active galactic nuclei (AGN) at redshifts . Here we present deep NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program UNCOVER of 15 AGN candidates selected to be compact, with red continua in the rest-frame optical but with blue slopes in the UV. From NIRCam photometry alone, they could have been dominated by dusty star formation or AGN. Here we show that the majority of the compact red sources in UNCOVER are dust-reddened AGN: show definitive evidence for broad-line H with FWHM km/s, for current data are inconclusive, and are brown dwarf stars. We propose an updated photometric criterion to select red AGN that excludes brown dwarfs and is expected to yield AGN. Remarkably, among all galaxies with F277WF444W in UNCOVER at least are AGN regardless of compactness, climbing to at least AGN for sources with F277WF444W. The confirmed AGN have black hole masses of M. While their UV-luminosities ( AB mag) are low compared to UV-selected AGN at these epochs, consistent with percent-level scattered AGN light or low levels of unobscured star formation, the inferred bolometric luminosities are typical of M black holes radiating at of Eddington. The number densities are surprisingly high at Mpc mag, 100 times more common than the faintest UV-selected quasars, while accounting for of the UV-selected galaxies. While their UV-faintness suggest they may not contribute strongly to reionization, their ubiquity poses challenges to models of black hole growth.