Systematic study of X-ray Cavities in the brightest galaxy of the Draco Constellation NGC 6338

TL;DR

This study systematically analyzes Chandra X-ray data of NGC 6338, revealing multiple cavities and filaments, their properties, and the nature of the ionizing sources, highlighting the dominance of mechanical jet power over radio emission.

Contribution

It provides a detailed characterization of X-ray cavities and filaments in NGC 6338, including their shapes, temperatures, and ionization sources, using archival Chandra data.

Findings

Multiple ellipsoidal X-ray cavities identified within 6 kpc.

X-ray filaments are cooler and aligned with Hα filaments.

Cavities are filled with radio emission but lack radio jets.

Abstract

We present results based on the systematic analysis of currently available Chandra archive data on the brightest galaxy in the Draco constellation NGC 6338, in order to investigate the properties of the X-ray cavities. In the central ~6 kpc, at least a two and possibly three, X-ray cavities are evident. All these cavities are roughly of ellipsoidal shapes and show a decrement in the surface brightness of several tens of percent. In addition to these cavities, a set of X-ray bright filaments are also noticed which are spatially coincident with the H{\alpha} filaments over an extent of 15 kpc. The H{\alpha} emission line filaments are perpendicular to the X- ray cavities. Spectroscopic analysis of the hot gas in the filaments and cavities reveal that the X-ray filaments are cooler than the gas contained in the cavities. The emission line ratios and the extended, asymmetric nature of the H{\alpha} emission line filaments seen in this system require a harder ionizing source than that produced by star formation and/or young, massive stars. Radio emission maps derived from the analysis of 1.4 GHz VLA FIRST survey data failed to show any association of these X-ray cavities with radio jets, however, the cavities are filled by radio emission. The total power of the cavities is 17\times 1042 erg s-1 and the ratio of the radio luminosity to cavity power is ~ 10-4, implying that most of the jet power is mechanical.