Fast Outflow in the Host Galaxy of the Luminous z $=$ 7.5 Quasar J1007$+$2115

TL;DR

This study reports the discovery of a fast, large-scale quasar-driven outflow at redshift 7.5, revealing early galaxy feedback processes with implications for galaxy evolution during reionization.

Contribution

First direct observation of a galactic-scale outflow in a luminous quasar at z=7.5 using JWST NIRSpec spectroscopy, demonstrating early feedback mechanisms.

Findings

Detected a 2 kpc, highly blueshifted outflow with velocities up to -870 km/s.

Outflow mass rate is 60-380% of the host galaxy's star formation rate.

Outflow kinetic energy is about 0.2% of the quasar's bolometric luminosity.

Abstract

James Webb Space Telescope opens a new window to directly probe luminous quasars powered by billion solar mass black holes in the epoch of reionization and their co-evolution with massive galaxies with unprecedented details. In this paper, we report the first results from the deep NIRSpec integral field spectroscopy study of a quasar at $z = 7.5$. We obtain a bolometric luminosity of $\sim$$1.8\times10^{47}$ erg s$^{-1}$ and a black hole mass of $\sim$0.7--2.5$\times10^{9}$ M$_{\odot}$ based on H$\beta$ emission line from the quasar spectrum. We discover $\sim$2 kpc scale, highly blueshifted ($\sim$$-$870 km/s) and broad ($\sim$1400 km/s) [O III] line emission after the quasar PSF has been subtracted. Such line emission most likely originates from a fast, quasar-driven outflow, the earliest one on galactic-scale known so far. The dynamical properties of this outflow fall within the typical ranges of quasar-driven outflows at lower redshift, and the outflow may be fast enough to reach the circumgalactic medium. Combining both the extended and nuclear outflow together, the mass outflow rate, $\sim$300 M$_{\odot}$yr, is $\sim$60%--380% of the star formation rate of the quasar host galaxy, suggesting that the outflow may expel a significant amount of gas from the inner region of the galaxy. The kinetic energy outflow rate, $\sim$3.6$\times10^{44}$ erg s$^{-1}$, is $\sim$0.2% of the quasar bolometric luminosity, which is comparable to the minimum value required for negative feedback based on simulation predictions. The dynamical timescale of the extended outflow is $\sim$1.7 Myr, consistent with the typical quasar lifetime in this era.