Speaker
Description
Active galactic nucleus (AGN) feedback is a key process in galaxy evolution, particularly at cosmic noon, when star formation and black hole accretion rates were at their peak. The jets and radiation are capable of injecting energy on the host galaxy and the circumgalactic medium (CGM) scales. In this context, high-redshift radio galaxies (HzRGs) are unique systems, as they host both — radio jets and a luminous type-2 quasar. These objects therefore allow us to study, within a single source, the combined impact of jets and quasar radiation in transporting energy from the nuclear region to CGM scales. With the JWST NIRSpec IFU, it is now possible to spatially resolve the impact of AGN on the surrounding gas in the high-redshift universe ($z > 3$).
I will present our analysis of the high-redshift radio galaxy 4C+03.24 at $z = 3.56$, using NIRSpec IFU observations to spatially resolve the properties of the ionised gas.
We find clear evidence for strong jet–gas interaction at a distance of ~12 kpc from the nucleus, bending the radio jet. We detect dense gas clumps, extending over a ~2 kpc region with electron densities of ~4300 cm$^{-3}$, that are likely responsible for the observed jet deflection. We find shock ionisation in the surrounding region due to this jet-gas interaction. Overall, we also investigate the ionisation mechanisms present in the entire system, out to a radial distance of ~15 kpc, tracing gas on CGM scales. A detailed comparison of the observed lines with radiative shock models reveals evidence for large-scale shocks in this system. The shock-ionised gas is distributed perpendicular to the inner jets and AGN ionisation cone, and we also detect precursor emission associated with gas-rich regions. These shocks significantly disturb the ionised gas, generating turbulence with line widths of FWHM = 1000–2000 km/s.
The observed electron densities and Balmer line luminosities are consistent with shock model predictions, supporting their origin in post-shock, radiatively cooling gas. We estimate that shocks ionise and disturb ~40% of the gas mass in this system, and contribute significantly to both the energy budget and the mass of the disturbed ionised medium. This demonstrates that jetted AGN at high redshift can drive shocks into the large-scale medium, and highlights how observations from next-generation facilities can be directly compared with models to constrain AGN feedback in the high-redshift universe.