Termination Shocks and the Extended X-ray Emission in MRK 78

TL;DR

This study uses high-resolution X-ray imaging to analyze shock structures and extended emission in the AGN Mrk 78, revealing complex morphology, spectral variations, and evidence of shocks associated with outflows.

Contribution

It provides detailed spatial and spectral analysis of Mrk 78's X-ray emission, highlighting shock features and their relation to outflow velocities, which advances understanding of AGN feedback mechanisms.

Findings

X-ray emission aligns with radio and emission line regions.

Evidence of shocks in both eastern and western structures.

Shocks inject 0.05-0.6% of AGN luminosity into the interstellar medium.

Abstract

Sub-arcsecond imaging of the X-ray emission in the type 2 AGN Mrk 78 with Chandra shows complex structure with spectral variations on scales from $\sim$200 pc to $\sim$ 2 kpc. Overall the X-ray emission is aligned E-W with the radio (3.6 cm) and narrow emission line region as mapped in [OIII], with a marked E-W asymmetry. The Eastern X-ray emission is mostly in a compact knot coincident with the location where the radio source is deflected, while the Western X-ray emission forms a loop or shell $\sim$2 kpc from the nucleus with radius $\sim$0.7 kpc. There is suggestive evidence of shocks in both the Eastern knot and the Western arc. Both these positions coincide with large changes in the velocities of the [OIII] outflow. We discuss possible reasons why the X-ray shocks on the Western side occur $\sim1$ kpc farther out than on the Eastern side. We estimate that the thermal energy injected by the shocks into the interstellar medium corresponds to $0.05-0.6$% of the AGN bolometric luminosity.