2023/07/26 by Sarah E. I. Bosman, Bosman, Sarah E. I., Javier Álvarez-Márquez +60
Engineering · Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Heat Transfer Mechanisms #Mechanics and Biomechanics Studies
paper · pdf · doi:10.48550/arxiv.2307.14414
openalex publication_date 2023/07/26 · openalex created_date 2023/07/29 · openalex updated_date 2026/08/03
We present a JWST/MRS spectrum of the quasar J1120+0641 at z=7.0848, the first spectroscopic observation of a reionisation-era quasar in the rest-frame infrared (0.6<λ<3.4μm). In the context of the mysterious fast assembly of the first supermassive black holes at z>7, our observations enable for the first time the detection of hot torus dust, the Hα emission line, and the Paschen-series broad emission lines in a quasar at z>7. Hot torus dust is clearly detected as an upturn in the continuum emission at λrest≃1.3μm, leading to a black-body temperature of T=1413.5+5.7-7.4K. Compared to similarly-luminous quasars at 06 (2σ significance). We measure the black hole mass of J1120+0641 based on the Hα Balmer line, MBH=1.52±0.17⋅ 109 M_\odot, which is in good agreement with the previous rest-UV MgII black hole mass measurement. The black hole mass based on the Paschen-series lines is also consistent, indicating no significant extinction in the rest-frame UV measurement. The broad Hα, Pa-α and Pa-β emission lines are consistent with an origin in a common broad-line region (BLR) with density logNH/cm-3≥ 12, ionisation parameter -7<logU<-4, and extinction E(B-V)\lesssim 0.1mag. These BLR parameters are consistent with similarly-bright quasars at 0