Journal Article

Uncovering a Massive z ∼ 7.7 Galaxy Hosting a Heavily Obscured Radio-loud Active Galactic Nucleus Candidate in COSMOS-Web

Paquereau, Louise, Clarke, Tracy E, Ilbert, Olivier, Vardoulaki, Eleni, Andika, Irham Taufik, Kleiner, Emma T, Chiaberge, Marco, Jahnke, Knud, Long, Arianna S, Onoue, Masafusa, Koekemoer, Anton M, Allen, Natalie, Gozaliasl, Ghassem, Stiavelli, Massimo, Shuntov, Marko, Norman, Colin, Dong, Dillon Z, Silverman, John D, Martin, Crystal L, Kokorev, Vasily, Rhodes, Jason, Trakhtenbrot, Benny, Ptak, Andrew F, Hutchison, Taylor A, Harish, Santosh, Nyland, Kristina, Jin, Shuowen, McCracken, Henry Joy, Capetti, Alessandro, Champagne, Jaclyn B, Toft, Sune, Hirschmann, Michaela, Kartaltepe, Jeyhan S, Cooper, Olivia R, Franco, Maximilien, Lambrides, Erini, man, Jordan Y, Manning, Sinclaire M, Faisst, Andreas L, Liu, Daizhong, Hayward, Christopher C, Casey, Caitlin M, Robertson, Brant E, Gillman, Steven, Hall, Kirsten R, Chworowsky, Katherine, Zavala, Jorge A, Akins, Hollis B, McKinney, Jed, Ding, Xuheng

2024

Overview

In this Letter, we report the discovery of the highest redshift, heavily obscured, radio-loud (RL) active galactic nucleus (AGN) candidate selected using JWST NIRCam/MIRI, mid-IR, submillimeter, and radio imaging in the COSMOS-Web field. Using multifrequency radio observations and mid-IR photometry, we identify a powerful, RL, growing supermassive black hole with significant spectral steepening of the radio spectral energy distribution (f 1.28 GHz ∼ 2 mJy, q 24 μm = −1.1, α 1.28−3 GHz = − 1.2, Δα = − 0.4). In conjunction with ALMA, deep ground-based observations, ancillary space-based data, and the unprecedented resolution and sensitivity of JWST, we find no evidence of AGN contribution to the UV/optical/near-infrared (NIR) data and thus infer heavy amounts of obscuration (N H > 1023 cm−2). Using the wealth of deep UV to submillimeter photometric data, we report a singular solution photo-z of z phot = 7.7−0.3+0.4 and estimate an extremely massive host galaxy (logM⋆=11.92±0.5M⊙) hosting a powerful, growing supermassive black hole​​​​​ (L Bol = 4−12x × 1046 erg s−1). This source represents the farthest known obscured RL AGN candidate, and its level of obscuration aligns with the most representative but observationally scarce population of AGN at these epochs.

• Publisher: IOP Publishing
• Subject: Accretion disks / Active galactic nuclei / Astronomy / Astrophysics / Black holes / Galaxies / Ground-based observation / James Webb Space Telescope / Observatories / Occultation / Photometry / Radio observation / Red shift / Space telescopes / Spectral energy distribution / Stars & galaxies / Supermassive black holes / Universe