GA-NIFS: Powerful and frequent outflows in moderate-luminosity AGN at $z\sim3-6$

TL;DR

This study presents the largest spatially resolved sample of AGN outflows at redshifts 3-6, revealing powerful outflows that likely played a significant role in early galaxy evolution.

Contribution

It provides new insights into the properties and cosmic evolution of AGN-driven outflows during a poorly explored epoch, using JWST NIRSpec IFU data.

Findings

High incidence (>75%) of ionised outflows in the sample.

Outflow velocities between ~600-2000 km/s with radii <1-4 kpc.

Evidence of stronger outflows at higher redshifts, especially z>3.

Abstract

The period between z ~ 3-6, a key transformational phase in galaxy evolution preceding `cosmic noon' (z ~ 1-3), is very poorly explored in terms of feedback from AGN acting through gas outflows. In this work, we study the properties of outflows in AGN (mostly X-ray-selected) from the GOODS-S field, exploiting JWST NIRSpec IFU observations as part of the GA-NIFS GTO survey. Together with its twin sub-sample from COSMOS reported in a previous GA-NIFS work, this constitutes the largest spatially resolved sample of AGN outflows at these redshifts to date, comprising 16 targets with outflows (out of a total of 19 AGN), and probes the unexplored regime of AGN at z ~ 3-6 with bolometric luminosities ~$10^{45-46}$ erg/s. We mapped the rest-optical ionised gas emission lines at sub-kpc scales and spectrally isolated the broad wings tracing fast outflows from the gas at rest in the host galaxies. The incidence of ionised outflows in the GOODS-S + COSMOS GA-NIFS sample is high (>75\%), among the highest at any redshift. We inferred outflow velocities between ~600-2000 km/s, maximum radii of <1-4 kpc, and ionised gas mass outflow rates of ~0.1-100 $M_\odot$/yr, which in some cases can exceed the host galaxy star formation rate (SFR). We find that the outflow properties inferred for the GOODS-S + COSMOS GA-NIFS AGN sample and their relations with $L_{\rm bol}$ and SFR generally align with those observed for other spatially resolved literature samples of AGN outflows across different redshifts and AGN luminosities. Nonetheless, after accounting for any luminosity bias, our analysis suggests a cosmic evolution of the outflow properties, with higher median mass outflow rates (and possibly also mass loading factors) at higher redshifts, especially at z>3, indicating that AGN outflows were stronger in the early Universe than at later times, and thus potentially more capable of affecting their host galaxy.