AGN Feedback: The impact of galactic-scale radio jets on the interstellar medium in starbursting obscured AGN

M. Polletta, C. J. Lonsdale, P. Pallavi, G. Vietri, A. E. Kimball, P. Franzetti, C. J. Lonsdale

First listed 2026-07-01 | Last updated 2026-06-30

Abstract

A highly star-forming galaxy at z ~ 2 hosting an obscured, luminous active galactic nucleus (AGN) and a relativistic radio jet sets the stage for a cosmic crime scene. The victim is star formation, the suspect is AGN feedback. These systems offer a rare opportunity to catch this process in the act. We propose SHARP@ELT integral-field spectroscopic observations of heavily obscured, luminous AGN with resolved radio emission to witness the onset of feedback and its impact on the host interstellar medium (ISM). Such objects trace a short-lived (< 10^5 yr) evolutionary phase in which a recent starburst, newly triggered radio jets, and a deeply embedded AGN coexist. In this phase, feedback is expected to suppress star formation while clearing the dusty nuclear regions. Using SHARP/VESPER, we will derive spatially resolved maps of stellar ages, star formation rate density, gas density, and ionization state, alongside the kinematics of stars and ionized gas. By directly comparing these properties with the radio structures, we will quantify the effects of both jet-driven and radiative feedback on the ISM. Our sample consists of eleven luminous, obscured AGN at 1.5 < z < 2.5 with resolved radio emission on scales of ~1-15 kpc. Exploiting the VESPER multi-Integral Field Selector capability, we will obtain resolved continuum and emission-line maps for at least 110 galaxies at cosmic noon, enabling a comprehensive characterization of their environment, multiphase ISM, and nuclear activity within 55 h of integration time. SHARP will thus reveal AGN feedback at the epoch when it is most effective, providing a decisive step toward understanding its role in galaxy evolution.

Short digest

Polletta et al. present an ELT/SHARP science case aimed at catching AGN feedback in the act in z~2 radio dusty obscured galaxies: heavily obscured, luminous AGN with recent starbursts and resolved radio jets on roughly 1-15 kpc scales. The paper argues that these sources trace a short-lived phase, shorter than 10^5 yr, in which a newly triggered jet and a deeply buried quasar coexist, making them unusually clean laboratories for testing whether feedback is suppressing star formation while clearing the nucleus. SHARP/VESPER integral-field spectroscopy would deliver resolved maps of stellar ages, star-formation-rate surface density, gas density, ionization state, and stellar and ionized-gas kinematics, to be compared directly with the radio structures. The proposed sample contains 11 such AGN at 1.5 < z < 2.5, and the multi-IFS strategy would scale this to at least 110 galaxies in 55 hours, turning the program into a direct test of jet-driven and radiative feedback at cosmic noon.

Key figures to inspect

• Figure 2. Use this as the motivating complexity figure. It shows the JWST/NIRSpec [O III] morphology and velocity-sliced structure of the obscured AGN J1652, together with the VESPER field of view, making clear why spatially resolved spectroscopy is needed to disentangle outflowing gas, shocked regions, companions, and tidal features in feedback-dominated systems.
• Figure 3. This is the cleanest sample-definition figure because it shows four of the selected radio DOGs in VLA 10 GHz imaging with annotated redshifts and radio morphologies. It establishes that the targets really do host resolved, galactic-scale radio structures rather than unresolved radio cores, which is central to the paper's jet-ISM feedback case.
• Figure 5. This figure provides the most direct physical diagnostic in the paper excerpt. The X-Shooter spectrum of J1500-06 shows two Gaussian components, including a component blueshifted by about -360 km/s, and the line-ratio behavior flagged in the caption as evidence for shocks, tying compact radio activity to disturbed ionized gas and outflow signatures.
• Figure 6. Include this later synthesis figure because it connects radio power, source size, and SHARP/VESPER observing feasibility across the full sample. It shows how the selected radio components occupy the sub-galactic to galactic scale regime and why a single IFS often suffices for one component while multiple IFSs are needed for more complex jet structures, directly supporting the proposed experimental design.