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This content will become publicly available on March 25, 2027

Title: Under Pressure: Ultraviolet Emission-line Ratios as Barometers of Active Galactic Nuclei Feedback Mechanisms
Abstract Feedback from active galactic nuclei (AGN) is widely acknowledged to regulate the growth of massive galaxies, though its driving mechanisms are debated. Prevailing theories suggest that AGN-driven outflows are driven either by radiation pressure acting directly on the dusty interstellar medium (ISM) or by hot winds entraining cooler ISM gas, but the relative contribution of each mechanism remains uncertain. By combining optical emission line measurements with highly ionized UV emission lines, it is possible to constrain whether the pressure source applied to ionized clouds is primarily radiation or primarily hydrodynamic, and thus constrain the dominant driver. This study presents the first multiobject analysis of far-UV spectra from galactic-scale AGN-driven outflows in obscured quasars, based on Cosmic Origins Spectrograph observations of five low-redshift targets. By comparing narrow-line region UV emission-line ratios to theoretical models that vary the importance of the two pressure sources, we find that three out of five targets fall within the radiation-pressure-dominated regime. A fourth target exhibits intermediate emission-line ratios that suggest radiation pressure and pressure from a hot wind are both dynamically important. Finally, the lowest-luminosity object in our sample may have a dynamically important hot wind component, but nondetections prevent a clear conclusion in this case. These results suggest radiation pressure dominates circumnuclear narrow-line region cloud dynamics, but pressure from a hot wind also plays a role in some cases. This is consistent with AGN feedback scenarios mediated by radiation pressure or a short-lived hot wind phase that dissipates after initially accelerating outflows.  more » « less
Award ID(s):
2307327 2108230
PAR ID:
10694817
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
ApJ
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
1000
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
229
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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