Imaging the Circumnuclear Region of NGC 1365 with Chandra

TL;DR

This study uses Chandra X-ray imaging to analyze the circumnuclear region of NGC 1365, revealing complex emission structures, starburst activity, and interactions between hot gas and star formation regions.

Contribution

First high-resolution Chandra imaging of NGC 1365's circumnuclear region, detailing the morphology, spectral properties, and interactions of hot gas, starburst activity, and nuclear features.

Findings

Extended soft X-ray emission shows a biconical structure aligned with optical outflows.

Hot ISM is consistent with enrichment from Type II supernovae.

Detection of a nuclear radio jet approximately 450 pc long.

Abstract

We present the first Chandra/ACIS imaging study of the circumnuclear region of the nearby Seyfert galaxy NGC 1365. The X-ray emission is resolved into point-like sources and complex, extended emission. The X-ray morphology of the extended emission shows a biconical soft X-ray emission region extending ~5 kpc in projection from the nucleus, coincident with the high excitation outflow cones seen in optical emission lines particularly to the northwest. Harder X-ray emission is detected from a kpc-diameter circumnuclear ring, coincident with the star-forming ring prominent in the Spitzer mid-infrared images; this X-ray emission is partially obscured by the central dust lane of NGC 1365. Spectral fitting of spatially separated components indicates a thermal plasma origin for the soft extended X-ray emission (kT=0.57 keV). Only a small amount of this emission can be due to photoionization by the nuclear source. Detailed comparison with [OIII]5007 observations shows the hot interstellar medium (ISM) is spatially anticorrelated with the [OIII] emitting clouds and has thermal pressures comparable to those of the [OIII] medium, suggesting that the hot ISM acts as a confining medium for the cooler photoionized clouds. The abundance ratios of the hot ISM are fully consistent with the theoretical values for enrichment from Type II supernovae, suggesting that the hot ISM is a wind from the starburst circumnuclear ring. X-ray emission from a ~450 pc long nuclear radio jet is also detected to the southeast.