The highly obscured Seyfert 2 nucleus in NGC 1448 observed with MUSE

TL;DR

This study uses MUSE optical data and Chandra X-ray observations to analyze the obscured Seyfert 2 nucleus in NGC 1448, revealing ionization cones, outflows, and a displaced AGN due to high obscuration and possible luminosity changes.

Contribution

First detailed optical integral field spectroscopy of NGC 1448's nucleus revealing the AGN's true position and ionization structure, highlighting the effects of obscuration and past luminosity variations.

Findings

AGN is offset from the stellar nucleus due to obscuration

Detection of two ionization cones with Seyfert-like spectra

Evidence of AGN outflows along ionization cones

Abstract

We present the analysis of an optical data cube of the central region of NGC 1448, obtained with the Multi Unit Spectroscopic Explorer (MUSE). Chandra X-ray data indicate that the active galactic nucleus (AGN) is not located at the apparent stellar nucleus of the galaxy, but at a projected distance of $1.75$ $\pm$ $0.22$ arcsec ($139 \pm 17$ pc). This is probably caused by the high interstellar extinction in the surroundings of the AGN, which corresponds to the true nucleus of the galaxy, as also proposed by previous studies. The morphology and classification of the optical line-emitting regions indicate two ionization cones, around an axis with a position angle of $PA_{cones}$ = -50{\deg} $\pm$ 7{\deg}, with emission-line spectra characteristic of Seyfert galaxies. The stellar and gas kinematics are consistent with a stellar and gas rotating disc around the nucleus, with a velocity amplitude of 125 km s$^{-1}$. Two probable outflows from the AGN were detected along the region of the two ionization cones. The AGN position does not coincide with the brightest line-emitting region at the centre of NGC 1448. That may be a consequence of the high obscuration from the AGN towards the observer (the AGN is actually Compton thick), mostly caused by a nearly edge-on torus. An additional hypothesis is that the AGN reduced its luminosity, during the last 440 yr, to nearly half of the value in the past. In this case, the brightest line-emitting region corresponds to a "light echo" or a "fossil" of the AGN in the past.