Integral Field Spectroscopy of the Extended Emission-Line Region of 4C 37.43

TL;DR

This study uses integral field spectroscopy to analyze the complex ionized gas in the extended emission-line region of quasar 4C 37.43, revealing a low-metallicity, two-phase medium driven by a spherical blast wave, supporting quasar feedback in galaxy evolution.

Contribution

It provides the first detailed photoionization and kinematic model of the EELR around 4C 37.43, highlighting a spherical blast wave mechanism for gas ejection and quasar feedback.

Findings

Ionized gas shows complex velocity structure incompatible with simple models.

Photoionization by the quasar fits the observed spectra better than shock models.

Estimated ionized gas mass is about 3x10^{10} solar masses, with significant kinetic energy.

Abstract

We present Gemini integral field spectroscopy and Keck II longslit spectroscopy of the extended emission-line region (EELR) around the quasar 4C 37.43. The velocity structure of the ionized gas is complex and cannot be explained globally by a simple dynamical model. The spectra from the clouds are inconsistent with shock or ``shock + precursor'' ionization models, but they are consistent with photoionization by the quasar nucleus. The best-fit photoionization model requires a low-metallicity (12+log(O/H) < 8.7) two-phase medium, consisting of a matter-bounded diffuse component with a unity filling-factor (N ~ 1 \cc, T ~ 15000 K), in which are embedded small, dense clouds (N ~ 400 \cc, T ~ 10^4 K). The high-density clouds are transient and can be re-generated through compressing the diffuse medium by low-speed shocks (V_S \lesssim 100 \kms). Our photoionization model gives a total mass for the ionized gas of about 3x10^{10} M_sun, and the total kinetic energy implied by this mass and the observed velocity field is ~2x10^{58} ergs. The fact that luminous EELRs are confined to steep-spectrum radio-loud quasars, yet show no morphological correspondence to the radio jets, suggests that the driving force producing the 4C 37.43 EELR was a roughly spherical blast wave initiated by the production of the jet. That such a mechanism seems capable of ejecting a mass comparable to that of the total interstellar medium of the Milky Way suggests that ``quasar-mode'' feedback may indeed be an efficient means of regulating star formation in the early universe.