Extended X-ray emission in radio galaxies: the peculiar case of 3C 305

TL;DR

This paper reports the first observation of extended X-ray emission in the CSS radio galaxy 3C 305, linked to the optical emission line region, and explores its thermal origin and possible mechanisms.

Contribution

It presents a detailed morphological analysis of 3C 305, revealing the thermal nature of its X-ray emission and proposing two potential origins related to outflows or nuclear photoionization.

Findings

X-ray emission is associated with the optical emission line region.

The X-ray emission is likely thermal and not jet-related.

Two possible origins for the X-ray structure are discussed.

Abstract

Extended X-ray structures are common in Active Galactic Nuclei (AGNs). Here we present the first case of a Compact Steep Spectrum (CSS) radio galaxy, 3C 305, in which the X-ray radiation appears to be associated with the optical emission line region, dominated by the [O III]5007. On the basis of a morphological study, performed using the comparison between the X-rays, the optical and the radio band, we argue that the high energy emission has a thermal nature and it is not directly linked to the radio jet and hotspots of this source. Finally, we discuss the origin of the extended X-ray structure connected with the optical emission line region following two different interpretations: as due to the interaction between matter outflows and shock-heated environment gas, or as due to gas photoionized by nuclear emission.