GA-NIFS: an extended [OIII]λ5007 halo around the sub-Eddington quasar J1342+0928 at z=7.54

The James Webb Space Telescope ( ) opened a new observational window on the primordial Universe. Here we present new JWST NIRSpec integral field spectroscopy (IFS) observations of the z=7.54 quasar ULAS J1342+0928 obtained as part of the Galaxy Assembly with NIRSpec IFS (GA-NIFS) GTO programme. The new data-set obtained with both the prism (R , with a mean (median) value of 480 (390) ̊m M_⊙ , JWST and the high-resolution grating (R emission on ∼7 kpc scales, well above the typical galaxy size at this redshift, likely associated with a past outflow event. Additionally, the high-resolution observations show a more energetic ionised outflow on nuclear scales (łesssim 0.8 kpc). The total ionised mass outflow rate ranges between ∼100 and 2200 ̊m M_⊙ , yr^ allow for a complete description of the quasar emission from the rest-frame UV to optical bands. The low-resolution data reveal the presence of O iii -1 -1 , where the significant spread is mostly due to the lack of tight constraints on the electron density and outflow geometry. This range broadly encompasses the star formation rate range (85--545 ̊m M_⊙ , yr^ -1 ), yet this only represents a lower limit to the total mass outflow rate. By employing an accretion disc modelling, for the first time on data, we manage to robustly estimate the black hole mass and the bolometric luminosity, ̊m łog(M_ JWST BH /(M_⊙))=9.1± 0.2 and ̊m łog(L_ bol /(erg , s^ -1 ))=46.8± 0.1, respectively. We derive an Eddington ratio of ̊m λ_ Edd ∼ 0.4, challenging the paradigm of widespread super-Eddington accretion in quasars at the epoch of re-ionisation. Lastly, we measure the most distant broad line ratios ( / and / ) so far. Interpreting these ratios as proxies to the broad line region metallicity, we find evidence for an early metal enrichment in quasars within 700 Myrs from the Big Bang. Fe ii UV Mg ii Fe ii opt H β