Professor Andrew Bunker

Abstract:

We present JWST Extragalactic Medium-band Survey, the first public medium-band imaging survey carried out using JWST/NIRCam and NIRISS. These observations use ∼2 and ∼4 μm medium-band filters (NIRCam F182M, F210M, F430M, F460M, F480M; and NIRISS F430M and F480M in parallel) over 15.6 arcmin2 in the Hubble Ultra Deep Field (UDF), thereby building on the deepest multiwavelength public data sets available anywhere on the sky. We describe our science goals, survey design, NIRCam and NIRISS image reduction methods, and describe our first data release of the science-ready mosaics, which reach 5σ point-source limits (AB mag) of ∼29.3-29.4 in 2 μm filters and ∼28.2-28.7 at 4 μm. Our chosen filters create a JWST imaging survey in the UDF that enables novel analysis of a range of spectral features potentially across the redshift range of 0.3 < z < 20, including Paschen-α, Hα+[N ii], and [O iii]+Hβ emission at high spatial resolution. We find that our JWST medium-band imaging efficiently identifies strong line emitters (medium-band colors >1 mag) across redshifts 1.5 < z < 9.3, most prominently Hα+[N ii] and [O iii]+Hβ. We present our first data release including science-ready mosaics of each medium-band image available to the community, adding to the legacy value of past and future surveys in the UDF. This survey demonstrates the power of medium-band imaging with JWST, informing future extragalactic survey strategies using JWST observations

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 Mdyn ∼ 1011 M and a rotation-to-random motion ratio vrot/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