A quasar–companion system without AGN outflow at z ∼ 6: the case of PSO J083 + 11
Year: 2026
Type: article
Abstract: ABSTRACT PSO J083.8371 + 11.8482, a quasar at $z = 6.34$ with a nearby companion galaxy, provides an opportunity to study the impact of active galactic nucleus (AGN) activity on the surrounding environment during the epoch of reionization. We analyse Atacama Large Millimeter/submillimeter Array observations of the [C ii] 158 $\mu$m emission line and the far-infrared (FIR) continuum, which trace cold interstellar gas and dust-reprocessed radiation from star formation and AGN heating. The quasar host shows star formation rates (SFRs) of 544–$3764~\mathrm{{\rm M}_{\odot }~yr^{-1}}$ from [C ii] and 1861–$2932~\mathrm{{\rm M}_{\odot }~yr^{-1}}$ from FIR emission, while the companion galaxy exhibits lower SFRs of 21–145 and 76–$211~\mathrm{{\rm M}_{\odot }~yr^{-1}}$ from the same diagnostics. Both galaxies follow typical $L_{\mathrm{[C\, II]}}/L_{\mathrm{FIR}}$ ratios observed in star-forming galaxies and show no evidence for a [C ii] deficit, indicating that stellar heating dominates the interstellar medium energetics. The [C ii] moment maps reveal compact emission with centrally peaked intensity and ordered rotational kinematics in both systems. Velocity dispersions remain well below values associated with powerful AGN-driven outflows, and no significant morphological asymmetries or disturbed velocity fields indicative of AGN feedback or major mergers are detected, although marginal kinematic substructure in the quasar’s high-velocity channels warrants further investigation. Although the companion lies at a projected distance of $18.248 \pm 0.277$ kpc within the quasar proximity zone, neither morphological nor kinematic signatures indicate AGN-driven outflows affecting the circumgalactic medium. We therefore interpret this system as being observed in a pre-outflow accretion phase, where rapid supermassive black hole growth precedes the development of large-scale AGN feedback.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
OpenAlex ID: W7160177196