GA-NIFS: The ultra-dense, interacting environment of a dual AGN at z ∼ 3.3 revealed by JWST/NIRSpec IFS

Abstract

Context. LBQS 0302−0019 is a blue quasar (QSO) at z ∼ 3.3 that hosts powerful outflows and resides in a complex environment consisting of an obscured active galactic nucleus (AGN) candidate and multiple companions, all within 30 kpc in projection.
Aims: We aim to characterise this complex system using JWST NIRSpec Integral Field Spectrograph (IFS) observations obtained as part of the NIRSpec IFS GTO programme "Galaxy Assembly with NIRSpec IFS" (GA-NIFS); these data cover the QSO rest-frame optical emission lines with a spatial resolution of ∼0.1″ and a sampling of 0.05″ (∼380 pc) over a contiguous sky area of ∼3″ × 3″ (23 × 23 kpc²).
Methods: We developed a procedure to correct for the spurious oscillations (or "wiggles") in NIRSpec single-spaxel spectra caused by the spatial under-sampling of the point spread function. We performed a QSO-host decomposition with the QDEBLEND3D tools. We used multi-component kinematic decomposition of the optical emission line profiles to infer the physical properties of the emitting gas in the QSO environment.
Results: The QSO-host decomposition allows us to identify both a low- and a high-velocity component. The former possibly traces a warm rotating disk with a dynamical mass M_dyn ∼ 10¹¹ M_⊙ and a rotation-to-random motion ratio v_rot/σ₀ ∼ 2. The other kinematic component traces a spatially unresolved ionised outflow with a velocity of ∼1000 km s⁻¹ and an outflow mass rate of ∼10⁴ M_⊙ yr⁻¹. We clearly detect eight companion objects close to LBQS 0302−0019. For two of them, we detect a regular velocity field that likely traces rotating gas, and we infer individual dynamical masses of ≈10¹⁰ M_⊙. Another companion shows evidence of gravitational interaction with the QSO host. Optical line ratios confirm the presence of a second, obscured AGN ∼20 kpc from the primary QSO; the dual AGN dominates the ionisation state of the gas in the entire NIRSpec field of view.
Conclusions: This work has unveiled in unprecedented detail the complex environment of LBQS 0302−0019, which includes its host galaxy, a close obscured AGN, and nine interacting companions (five of which were previously unknown), all within 30 kpc of the QSO. Our results support a scenario where mergers can trigger dual AGN and can be important drivers of rapid early supermassive black hole growth.

JWST/NIRSpec integrated spectrum of the blue quasar LBQS 0302-0019 is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/679/A89