Outflowing Diffuse Gas in the Active Galactic Nucleus of NGC 1068

TL;DR

This study detects outflowing diffuse gas near the nucleus of NGC 1068 using H3+ absorption lines, estimating a mass outflow rate of about 1 solar mass per year, revealing active gas dynamics close to the AGN.

Contribution

First detection of H3+ absorption indicating outflow in NGC 1068, providing new insights into AGN-driven gas dynamics within a few tens of parsecs.

Findings

H3+ absorption shows outflow velocity of -70 km/s.

Diffuse gas near the nucleus is involved in the outflow.

Estimated mass outflow rate is approximately 1 solar mass per year.

Abstract

Spectra of the archetypal Type II Seyfert galaxy NGC 1068 in a narrow wavelength interval near 3.7 microns have revealed a weak absorption feature due to two lines of the molecular ion H3+. The observed wavelength of the feature corresponds to velocity of -70 km/s relative to the systemic velocity of the galaxy, implying an outward flow from the nucleus along the line of sight. The absorption by H3+ along with the previously known broad hydrocarbon absorption at 3.4~microns probably are formed in diffuse gas that is in close proximity to the continuum source, i.e. within a few tens of parsecs of the central engine. Based on that conclusion and the measured H3+ absorption velocity and with the assumption of a spherically symmetric wind we estimate a rate of mass outflow from the AGN of ~1 Msun/yr.