Chandra View of the LINER-type Nucleus in the Radio-Loud Galaxy CGCG 292-057: Ionized Iron Line and Jet-ISM Interactions

TL;DR

This paper analyzes deep Chandra X-ray observations of the radio-loud galaxy CGCG 292-057, revealing complex interactions between jet activity, ionized iron emission, and the interstellar medium, with implications for understanding LINER nuclei.

Contribution

It provides the first detailed X-ray spectral analysis of CGCG 292-057, highlighting ionized iron emission and jet-ISM interactions in a restarted radio galaxy with LINER characteristics.

Findings

Detection of ionized iron line at 6.7 keV.

Evidence of jet-induced heating of the interstellar medium.

X-ray spectrum consistent with a Compton-thin, photoionized gas near the broad-line region.

Abstract

We present an analysis of the new, deep (94\,ksec) {\it Chandra} ACIS-S observation of radio-loud active galaxy CGCG\,292$-$057, characterized by a LINER-type nucleus and a complex radio structure that indicates intermittent jet activity. On the scale of the host galaxy bulge, we detected excess X-ray emission with a spectrum best fit by a thermal plasma model with a temperature of $\sim 0.8$\,keV. We argue that this excess emission results from compression and heating of the hot diffuse fraction of the interstellar medium displaced by the expanding inner, $\sim 20$\, kpc-scale lobes observed in this restarted radio galaxy. The nuclear X-ray spectrum of the target clearly displays an ionized iron line at $\sim 6.7$\,keV, and is best fitted with a phenomenological model consisting of a power-law (photon index $\simeq 1.8$) continuum absorbed by a relatively large amount of cold matter (hydrogen column density $\simeq 0.7 \times 10^{23}$\,cm$^{-2}$), and partly scattered (fraction $\sim 3\%$) by ionized gas, giving rise to a soft excess component and K$\alpha$ line from iron ions. We demonstrate that the observed X-ray spectrum, particularly the equivalent width of Fe\,\texttt{XXV} K$\alpha$ (of order $0.3$\,keV) can in principle, be explained in a scenario involving a Compton-thin gas located at the scale of the broad-lined region in this source and photoionized by nuclear illumination. We compare the general spectral properties of the CGCG\,292$-$057 nucleus, with those of other nearby LINERs studied in X-rays.