Feedback in Luminous Obscured Quasars

TL;DR

This study uses spatially resolved spectroscopy to analyze the size, kinematics, and ionization of narrow-line regions in luminous obscured quasars, revealing galaxy-wide gas disturbance and feedback effects.

Contribution

It provides new measurements of narrow-line region sizes and kinematics across a broader luminosity range, demonstrating galaxy-wide AGN influence and discovering dual quasars with large-scale ionized gas bubbles.

Findings

Narrow-line region size scales with luminosity with a slope of 0.22.

AGN ionizes gas throughout the entire host galaxy.

Gas kinematics are highly disturbed, with constant velocity dispersions at large radii.

Abstract

We use spatially resolved long-slit spectroscopy from Magellan to investigate the extent, kinematics, and ionization structure in the narrow-line regions of 15 luminous, obscured quasars with z<0.5. Increasing the dynamic range in luminosity by an order of magnitude, as well as improving the depth of existing observations by a similar factor, we revisit relations between narrow-line region size and the luminosity and linewidth of the narrow emission lines. We find a slope of 0.22 +/- 0.04 for the power-law relationship between size and luminosity, suggesting that the nebulae are limited by availability of gas to ionize at these luminosities. In fact, we find that the active galactic nucleus is effectively ionizing the interstellar medium over the full extent of the host galaxy. Broad (~300-1000 km/s) linewidths across the galaxies reveal that the gas is kinematically disturbed. Furthermore, the rotation curves and velocity dispersions of the ionized gas remain constant out to large distances, in striking contrast to normal and starburst galaxies. We argue that the gas in the entire host galaxy is significantly disturbed by the central active galactic nucleus. While only ~10^7-10^8 M_sun worth of gas are directly observed to be leaving the host galaxies at or above their escape velocities, these estimates are likely lower limits because of the biases in both mass and outflow velocity measurements and may in fact be in accord with expectations from recent feedback models. Additionally, we report the discovery of two dual obscured quasars, one of which is blowing a large-scale (~10 kpc) bubble of ionized gas into the intergalactic medium.