A JWST/NIRSpec Integral Field Unit Survey of Luminous Quasars at z ~ 5-6 (Q-IFU): Rest-frame Optical Nuclear Properties and Extended Nebulae

Weizhe Liu, Xiaohui Fan, Huan Li, Richard Green, Jaclyn B. Champagne, Xiangyu Jin, Jianwei Lyu, Maria Pudoka, Wei Leong Tee, Feige Wang, Jinyi Yang, Yongda Zhu, Nayera Abdessalam

First listed 2025-11-08 | Last updated 2025-11-08

Abstract

It remains debatable how billion-solar-mass supermassive black holes (SMBHs) form and evolve within the first billion years. We report results from a James Webb Space Telescope (JWST)/NIRSpec integral field unit (IFU) survey of 27 luminous quasars at $z \sim 5$-$6$, enabling a systematic investigation of their key physical properties and the associated, extended line emission. Our sample hosts SMBHs with $\log(M_{\mathrm{BH}}/M_\odot) \sim 8.6$-$9.7$ and Eddington ratios of $\sim 0.1$-$2.6$ based on H$β$, and the H$β$-based and H$α$-based BH mass are broadly consistent with each other. Our sample may have a slightly smaller median BH mass and larger median Eddington ratio than lower-redshift quasars within the same luminosity range, although the difference could still be explained by statistical uncertainties. They generally follow the empirical correlations between [O III] $λ$5007 equivalent width and bolometric luminosities or Eddington ratios formed by lower-redshift quasars. The majority of them fall within the Eigenvector~1 planes formed by lower-redshift quasars. Nevertheless, a subset of the sample shows enhanced, blueshifted [O III] emission associated with fast outflows. Spatially extended [O III] line emission is detected in 6 objects and shows morphologies and kinematics consistent with merging activities and/or turbulent and clumpy interstellar media (ISM). Tentative evidence of quasar radiative feedback shaping the ISM of a merging companion galaxy is seen in the object with the most extended [O III] emission. Our results provide crucial insight into the rapid growth of SMBHs and the gaseous environments they reside in at z$\sim$5-6.

Short digest

Q-IFU uses JWST/NIRSpec IFU to obtain rest‑frame optical spectra for 27 luminous quasars at z ~5–6, measuring nuclear properties and searching for extended nebulae. Hβ yields log(MBH/M⊙) ≈ 8.6–9.7 and λEdd ≈ 0.1–2.6, broadly consistent with Hα; relative to luminosity-matched lower‑z samples the median MBH is slightly smaller and λEdd slightly larger, but differences are within statistical uncertainties. [O III] λ5007 EW tracks Lbol and λEdd as at low z and most sources lie on EV1 planes, while a subset shows enhanced, blueshifted [O III] signaling fast outflows. Six objects exhibit spatially extended [O III] with merger‑like or turbulent, clumpy kinematics, including tentative evidence that quasar radiation is reshaping a companion’s ISM in the system with the largest nebula.

Key figures to inspect

• Figure 1: Check where the 27 targets sit in M1450–z space relative to the literature sample to gauge luminosity matching and the two redshift windows used for grating placement.
• Figure 2: Inspect rest‑optical–based systemic redshifts versus UV‑line redshifts to quantify typical Δz offsets that impact outflow blueshift measurements and BH‑mass calibrations.
• Figure 3: Compare the Q‑IFU composite to the luminosity‑matched z~1.5–3.5 Shen sample—focus on Hβ profile, Fe II strength, and [O III] EW to see the EV1 placement and Baldwin‑type trends at z~5–6.
• Figure 4: Read the Lbol–MBH diagram with Eddington‑ratio lines to see the distribution (log MBH ~8.6–9.7; λEdd up to >1) and the mild shift toward higher accretion rates versus lower‑z quasars, plus context from ASPIRE and SDSS.
• Appendix Fig. 11: Use the individual Hβ+[O III] (and Hα where available) fits to verify multi‑component decompositions, blueshifted [O III] wings, and the tied broad‑line kinematics used for MBH estimates.