The Nuclear Outflow in NGC 2110

TL;DR

This study uses spectroscopic and imaging data to analyze the nuclear outflow in NGC 2110, suggesting the radio jet's ram pressure as the primary acceleration mechanism for the emission line gas.

Contribution

It provides a detailed geometrical and dynamical model of the NLR, emphasizing the role of the radio jet and circum-nuclear disc in shaping the outflow.

Findings

The linear NLR structure is strongly accelerated by the jet.

Photoionisation by the active nucleus explains the ionisation properties.

Radio jet ram pressure is the most likely outflow driver.

Abstract

We present a HST/STIS spectroscopic and optical/radio imaging study of the Seyfert NGC 2110 aiming to measure the dynamics and understand the nature of the nuclear outflow in the galaxy. Previous HST studies have revealed the presence of a linear structure in the Narrow-Line Region (NLR) aligned with the radio jet. We show that this structure is strongly accelerated, probably by the jet, but is unlikely to be entrained in the jet flow. The ionisation properties of this structure are consistent with photoionisation of dusty, dense gas by the active nucleus. We present a plausible geometrical model for the NLR, bringing together various components of the nuclear environment of the galaxy. We highlight the importance of the circum-nuclear disc in determining the appearance of the emission line gas and the morphology of the jet. From the dynamics of the emission line gas, we place constraints on the accelerating mechanism of the outflow and discuss the relative importance of radio source synchrotron pressure, radio jet ram pressure and nuclear radiation pressure in accelerating the gas. While all three mechanisms can account for the energetics of the emission line gas, gravitational arguments support radio jet ram pressure as the most likely source of the outflow.